JP5082111B2 - Computer system, service utilization apparatus, control method, and program - Google Patents

Description

  The present invention relates to a computer system, a service providing apparatus, a service using apparatus, a control method, and a program. In particular, the present invention relates to a computer system that provides and uses a service, a service providing device that provides a service, a service using device that uses a provided service, a computer system, a service providing device, and a control method for controlling the service using device, The present invention also relates to a program for the computer system, the service providing apparatus, and the service using apparatus.

A data sharing system that stores a connection that connects an application installed in a client terminal and a database, acquires a normally operating connection from the stored connections, and has a connection storage unit that connects the application and the database. It is known (for example, refer to Patent Document 1). In this system, the application server accesses the database server using connections stored in the connection pool. At this time, the application server discards the connection that does not operate normally and creates a new connection.
JP 2003-216477 A

  According to the data sharing system described in Patent Document 1, a connection that does not operate normally is discarded and a new connection is generated. However, when the processing load is further sent from the application server through the accumulated connection when the load on the database server increases, the load on the database server may exceed its processing capability. In addition, since the process of establishing a connection with the application server by the database server is a process with a high processing cost for the database server, if the application server tries to create a new connection while the load on the database is increasing, the database server The load is further increased.

  In order to solve the above problem, according to a first aspect of the present invention, there is provided a computer system, a service providing unit that provides a service, a service using unit that uses a service provided by the service providing unit, and a service use A connection establishment unit that establishes in advance a plurality of connections for communication with the service providing unit, a load detection unit that detects a load value of a computer operating as the service providing unit, and a load value detected by the load detection unit increases A connection control unit that reduces the number of connections that can be used by the service utilization unit among the connections established by the connection establishment unit.

  The connection control unit may reduce the number of connections that can be used when the load value detected by the load detection unit becomes greater than a predetermined connection number reduction load value. In addition, the load value detected by the load detection unit may include at least one of a resource usage amount of the computer or a time length required for the service providing unit to respond to the outside. The usage amount of the resource may include a usage rate of a CPU included in the computer.

  The connection control unit can be used by disconnecting the connection established by the connection establishment unit when the load value detected by the load detection unit becomes larger than a predetermined connection number reduction load value. The number of connections may be reduced.

  The connection control unit further includes a connection number storage unit that stores a smaller number of connections that can be used in association with a larger load value, and the load control unit detects the number of connections that can be used. The number of connections stored in the connection number storage unit may be controlled in association with the load value.

  After reducing the number of connections that can be used, the connection control unit can use the number of connections that can be used when the load value detected by the load detection unit falls below a predetermined connection number increase load value. May be increased.

  The service providing unit may be provided in a database server that stores data and provides the data to the outside, and the service using unit may use data provided by the database server. The service using unit may be provided in an application server different from the database server that provides services to the outside using data provided by the database server.

  A plurality of application servers are provided, a load acquisition unit and a connection control unit are provided in each of the plurality of application servers, and a connection control unit provided in each of the plurality of application servers is connected to the load value acquired by the load acquisition unit. When the load value is larger than the number reduction load value, the number of connections that can be used by each of the service using units provided in each of the plurality of application servers may be reduced.

  According to a second aspect of the present invention, there is provided a control method for controlling a computer system including a service using unit that uses a service provided by a service providing unit that provides a service, wherein the service using unit communicates with the service providing unit. A connection establishment stage for establishing a plurality of connections in advance, a load detection stage for detecting a load value of a computer operating as a service providing unit, and a connection establishment stage when the load value detected in the load detection stage increases A connection control step for reducing the number of connections that can be used by the service using unit among the connections established in step (b).

  According to the third aspect of the present invention, there is provided a program for a computer system, the service providing unit providing the service, the service using unit using the service provided by the service providing unit, and the service using unit providing the service. A connection establishment unit that establishes a plurality of connections for communication with the providing unit in advance, a load detection unit that detects a load value of a computer that operates as a service providing unit, and a connection when the load value detected by the load detection unit increases Of the connections established by the establishment unit, the service utilization unit functions as a connection control unit that reduces the number of connections that can be used.

  According to the fourth aspect of the present invention, there are a plurality of connections that can be used by the service using device, which are preset in the service using device that provides the service and that uses the service provided by the service providing device. Are established by the connection establishment unit when the load value detected by the load detection unit increases, when the load value detected by the load detection unit increases. A connection control unit that reduces the number of connections that can be used by the service using device among the connections being used.

  According to the fifth aspect of the present invention, there is provided a control method for controlling a service providing apparatus that provides a service, wherein the service using apparatus preset in the service using apparatus that uses the service provided by the service providing apparatus is used. A connection establishment stage that establishes a plurality of possible connections with a service using apparatus in advance, a load detection stage that detects a load value of a service providing apparatus, and a load value detected in the load detection stage increases. A connection control stage for reducing the number of connections that can be used by the service using apparatus among the connections established in the connection establishment stage.

  According to the sixth aspect of the present invention, there is provided a program for a service providing apparatus that provides a service, wherein the service providing apparatus is preset in a service using apparatus that uses a service provided by the service providing apparatus. A connection establishment unit that establishes a plurality of connections that a device can use in advance with a service using device, a load detection unit that detects a load value of a service providing device, and a load value detected by the load detection unit increases The connection control unit functions as a connection control unit that reduces the number of connections that can be used by the service using apparatus among the connections established by the connection establishment unit.

  According to a seventh aspect of the present invention, there is provided a service using device that uses a service provided by a service providing device, wherein the service using device establishes in advance a plurality of connections for communicating with the service providing device; A load acquisition unit that acquires a load value of a service providing device, and when the load value acquired by the load acquisition unit increases, the service using device can use the connection established by the connection establishment unit A connection control unit for reducing the number of connections.

  According to an eighth aspect of the present invention, there is provided a control method for controlling a service using apparatus that uses a service provided by a service providing apparatus, wherein the service using apparatus establishes a plurality of connections for communicating with the service providing apparatus in advance. A connection establishment stage, a load acquisition stage for acquiring a load value of the service providing apparatus, and when the load value acquired in the load acquisition stage increases, the service using apparatus among the connections established in the connection establishment stage A connection control step for reducing the number of connections that can be used.

  According to a ninth aspect of the present invention, there is provided a program for a service using device that uses a service provided by a service providing device, wherein the service using device communicates with the service providing device by a plurality of connections. A connection establishment unit that establishes in advance, a load acquisition unit that acquires a load value of a service providing device, and a service utilization device among the connections established by the connection establishment unit when the load value acquired by the load acquisition unit increases It functions as a connection control unit that reduces the number of connections that can be used.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  As apparent from the above description, according to the present invention, the number of connections between the service using device and the service providing device can be appropriately controlled according to the load value of the service providing device.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows an example of a usage environment of a computer system 100 according to an embodiment. The computer system 100 includes a plurality of application servers 120a, b, c,... (Hereinafter collectively referred to as application servers 120), a database server 110, a plurality of WEB servers 130a, b, c,. (Referred to collectively as a server 130), a load balancer 140, a plurality of client terminals 160a, b, c,... (Hereinafter collectively referred to as a client terminal 160), and a communication line 150.

  Note that the communication line 150 includes a computer network such as the Internet, a core network of a communication carrier, and various local networks. The client terminal 160 includes a mobile phone, a personal digital assistant such as a PDA, and a personal computer.

  The client terminal 160 transmits a request such as an HTTP request to any of the WEB servers 130 through the communication line 150. Specifically, the client terminal 160 transmits a request to the load balancer 140. When receiving a request from the client terminal 160, the load balancer 140 selects a WEB server 130 to which the request is to be transmitted from a plurality of WEB servers 130 according to a predetermined load distribution algorithm, and sends the request to the selected WEB server 130. Send. The WEB server 130 executes processing according to the received request, and transmits the processing result to the client terminal 160 through the load balancer 140.

  The WEB server 130 requests processing from at least one of the application servers 120 based on the content of the received request. The application server 120 advances the processing of the requested content and transmits the processing result to the WEB server 130. At this time, the application server 120 accesses the database server 110 as necessary when executing the requested processing. Specifically, the application server 120 reads data from the database server 110, processes the read data and transmits it to the WEB server 130, adds data to the database server 110, and stores the data in the database server 110. Update the stored data or delete the data stored in the database server 110. In this way, the database server 110 stores data and provides the stored data to the outside. The application server 120 uses the data provided by the database server 110 to provide a service to the outside.

  Each application server 120 establishes one or more predetermined connections with the database server 110 at the time of activation. Then, when accessing the database server 110, the application server 120 accesses the database server 110 using a connection established in advance. The application server 120 holds the connection even after the access to the database server 110 is finished, and uses the held connection when connecting to the database server 110 later. The application server 120 can establish and hold a plurality of connections in advance, and can simultaneously access the database server 110 using the plurality of held connections. As described above, the application server 120 establishes a connection in advance and holds the established connection even after the session ends, so that connection generation processing with high processing cost for the database server 110 frequently occurs. May be able to prevent.

  The application server 120 acquires the usage rate (hereinafter referred to as CPU usage rate) of the central processing unit (CPU) included in the database server 110 from the database server 110. Then, when the CPU usage rate becomes larger than a predetermined value, the application server 120 reduces the number of connections that can be used by the application server 120 (hereinafter may be referred to as the number of usable connections). At this time, the application server 120 may prohibit the use of a predetermined number of connections according to the CPU usage rate while holding the connection with the database server 110, or may actually use the predetermined number of connections. It may be cut.

  Then, when the CPU usage rate becomes smaller than a predetermined value, the application server 120 increases the number of usable connections of the application server 120. At this time, the application server 120 may permit the use of at least a part of the predetermined number of connections that have been prohibited from being used while maintaining the connection with the database server 110, or When disconnected, a predetermined number of connections with the database server 110 may be newly established.

  As described above, the application server 120 controls the number of connections that the application server 120 can access to the database server 110 at the same time according to the load value of the database server 110, so that the database server 110 is overloaded. In some cases, the database server 110 can continuously provide services.

  In the present embodiment, the configuration in which the computer system 100 includes one database server 110 has been described for the purpose of preventing the description from becoming complicated. However, the computer system 100 may include a plurality of database servers 110. . Further, the computer system 100 of the present embodiment can function as a database system as described above.

  FIG. 2 shows an example of a block configuration of the database server 110 and the application server 120. The application server 120a includes a connection establishment unit 200a, a load acquisition unit 210a, a connection control unit 220a, a connection number storage unit 230a, a connection information storage unit 240a, a service use unit 250a, and a communication control unit 290a. The database server 110 includes a connection establishment unit 200A, a load detection unit 215A, a connection control unit 220A, a connection number storage unit 230A, a connection information storage unit 240A, and a communication control unit 290A. The database server 110 may be an example of a service providing apparatus according to the present invention, and the application server 120 may be an example of a service using apparatus according to the present invention.

  Note that the application servers 120b, c,... Other than the application server 120a also have the same components as the components of the application server 120a. In the following description, when distinguishing which component of the application server 120 the component of the application server 120 is, the same subscript (a, b, c) as that of the application server 120 having each component Is added to the end of each component to distinguish them. For example, the connection establishment unit 200a, the connection establishment unit 200b, and the connection establishment unit 200c indicate that they are components of the application server 120a, the application server 120b, and the application server 120c, respectively.

  Further, in the following description, the function and operation of a component that is not given a subscript indicates the function and operation of any component that is assigned the same reference numeral. For example, the functions and operations described in connection establishment unit 200 indicate the functions and operations of connection establishment unit 200a, connection establishment unit 200b, connection establishment unit 200c,. In addition, among the components of the database server 110 and the application server 120, components having the same name and having the same reference numerals indicate similar functions and operations, and therefore, functions and operations of components without subscripts are 2 shows functions and operations of components included in the database server 110 and the application server 120. Therefore, for example, the functions and operations of the connection control unit 220 indicate the functions and operations of the connection control unit 220A, the connection control unit 220a, the connection control unit 220b, and the connection control unit 220c.

  The function and operation of each component will be described below. The service providing unit 255A provides a service. The service here includes not only a data providing service using a database function, which is described as an example of a service in this embodiment, but also various services such as a Web service, an e-mail service, a file service, and a printing service. In the present embodiment, the service providing unit 255A functions as a database that provides data stored in a recording medium such as a hard disk or a semiconductor memory to the outside. Note that the recording medium may be non-volatile or volatile.

  The service using unit 250 uses a service provided by the service providing unit 255A. Specifically, the service using unit 250 performs various processes using data provided by the database server 110. The connection establishing unit 200 establishes in advance a plurality of connections for the service using unit 250 to communicate with the service providing unit 255A. Specifically, the connection establishment unit 200 </ b> A establishes in advance with the application server 120 a plurality of connections that can be used by the application server 120 that are set in advance in the application server 120. For example, the connection establishment unit 200A establishes a connection in response to a connection establishment request from the connection establishment unit 200a. In this way, the connection establishment unit 200a establishes in advance a plurality of connections for the application server 120 to communicate with the database server 110. The connection information storage unit 240 stores connection information used for using the connection established by the connection establishment unit 200.

  The load detection unit 215A detects the load value of the computer that operates as the service providing unit 255A. Specifically, the load detection unit 215A detects the load value of the database server 110. The load value detected by the load detection unit 215A includes at least one of the amount of resource used by the computer or the time required for the service providing unit 255A to respond to the outside. The resource usage includes the CPU usage rate of the computer. The load acquisition unit 210 acquires the load value detected by the load detection unit 215A from the database server 110. As described above, the load acquisition unit 210 acquires the load value of the database server 110.

  The connection control unit 220 reduces the number of connections that can be used by the service using unit 250 among the connections established by the connection establishment unit 200 when the load value detected by the load detection unit 215A increases. . Specifically, the connection control unit 220 reduces the number of connections that can be used when the load value acquired by the load acquisition unit 210 is greater than the connection number reduction load value. More specifically, the connection control unit 220 reduces the number of connections that can be used when the load value detected by the load detection unit 215A is greater than a predetermined connection number reduction load value. Note that the connection control unit 220 disconnects the connection established by the connection establishment unit 200 when the load value detected by the load detection unit 215A is greater than a predetermined connection number reduction load value, The number of connections that can be used may be reduced. In this way, the connection control unit 220 determines the number of connections that can be used by the database server 110 among the connections established by the connection establishment unit 200 when the load value detected by the load detection unit 215A increases. Decrease.

  More specifically, the connection number storage unit 230 stores a smaller number of connections that can be used in association with a larger load value. Then, the connection control unit 220 controls the number of connections that can be used to the number of connections stored in the connection number storage unit 230 in association with the load value detected by the load detection unit 215A. Note that the connection control unit 220 is used when the load value detected by the load detection unit 215A falls below a predetermined connection number increase load value after reducing the number of connections that can be used. Increase the number of connections that can be The connection number increasing load value may be a value equal to or less than the connection number decreasing load value.

  A plurality of service utilization units 250 may be provided. Specifically, each of the plurality of application servers 120 may include a service usage unit 250. Then, the connection establishing unit 200 establishes a plurality of connections between each of the plurality of service using units 250 and the service providing unit 255A. Then, the connection control unit 220 reduces the number of connections that each of the plurality of service using units 250 can use when the load value detected by the load detection unit 215A becomes larger than the connection number reduction load value. Let

  The connection establishing unit 200 is provided for each of the plurality of service using units 250. Specifically, each of the plurality of application servers 120 has a connection establishment unit 200. Then, the connection establishment unit 200 provided for each of the plurality of service use units 250 establishes a plurality of connections between each of the plurality of service use units 250 and the service providing unit 255A. The connection control unit 220 is provided for each of the plurality of service using units 250. Specifically, each of the plurality of application servers 120 includes a connection control unit 220. Then, when the load value detected by the load detection unit 215A is greater than the connection number reduction load value, the connection control unit 220 provided for each of the plurality of service use units 250 has a plurality of service use units 250. Reduce the number of connections each can use.

  The connection usage number detecting unit 280A detects the number of connections currently used by each of the plurality of service using units 250 among the connections that can be used by each of the plurality of service using units 250. Then, when the load value detected by the load detection unit 215A is greater than the connection number decreasing load value, the connection control unit 220A determines the number of connections detected by the connection usage number detection unit 280A and the number of service usage units 250. Based on the number of connections that each can use, the ratio of the number of connections used by the service using unit 250 to the number of connections that can be used by the service using unit 250 is a plurality of service using units 250. The number of connections that can be used by at least one of the plurality of service using units 250 is reduced in the same direction.

  In addition, the connection control unit 220A reduces the number of connections that can be used, and the connection usage number when the load value detected by the load detection unit 215A becomes smaller than a predetermined connection number increase load value. Based on the number of connections detected by the detecting unit 280A and the number of connections that each of the plurality of service using units 250 can use, the service using unit 250 for the number of connections that the service using unit 250 can use is used. The number of connections that can be used by at least one of the plurality of service using units 250 may be increased in a direction in which the ratio of the number of connections used is equal among the plurality of service using units 250.

  Note that the connection control unit 220 provided in each of the plurality of application servers 120 is provided in each of the plurality of application servers 120 when the load value acquired by the load acquisition unit 210 is greater than the load number reduction load value. The number of connections that can be used by each of the service use units 250 is reduced. Note that the connection control unit 220A issues a command to reduce the number of connections that can be used when the load value detected by the load detection unit 215A is greater than a predetermined connection number reduction load value. 120 may be transmitted. In addition, the connection control unit 220 determines the connection established by the connection establishment unit 200 when the load value detected by the load detection unit 215A is greater than a predetermined disconnection load value that is greater than the connection number reduction load value. By disconnecting, the number of connections that can be used may be reduced.

  FIG. 3 shows an example of an operation sequence of the WEB server 130, the application server 120, and the database server 110. When the application server 120 is activated (S302), the load acquisition unit 210a requests the load value of the database server 110 from the load detection unit 215A (S304). The load detection unit 215A detects the load value of the database server 110 and transmits it to the load acquisition unit 210a (S306).

  The connection establishment unit 200a sets the number of usable connections based on the information stored in the connection number storage unit 230a according to the load value acquired by the load acquisition unit 210a (S308). Then, the connection establishment unit 200a and the connection establishment unit 200A establish a connection (S312a, S312b). At this time, the connection establishment unit 200a and the connection establishment unit 200A generate one or more predetermined numbers (for example, 20) of connections permitted by the application server 120a. Note that the number of connections established here may be predetermined as a set value for each application server 120.

  Then, the service using unit 250a receives a processing request from the WEB server 130 (S322). The service using unit 250a proceeds with processing according to a predetermined logic defined by the program based on the received processing request or the like. At this time, the service using unit 250a generates a query to be executed by the database server 110 (S324). Then, the service using unit 250a selects an unused connection from the established connections (S326), and transmits a query to the database server 110 using the selected connection (S328).

  The service providing unit 255A executes the received query (S330), and transmits the execution result of executing the query to the application server 120 (S322). At this time, the communication control unit 290A transmits the execution result using the connection established with the application server 120. Then, the service using unit 250a generates a processing result using the received execution result (S334), and transmits the generated processing result to the WEB server 130 (S336). When the load detection unit 215A detects a load value that exceeds the disconnection load value (S342), the connection control unit 220A disconnects the number of connections corresponding to the load value (S344).

  The service using unit 250a holds the connection without disconnecting the connection even when a series of sessions with the service providing unit 255A is completed. Then, when communicating with the service providing unit 255A later, the service using unit 250a selects and uses a connection that can be used from the held connections as in S326.

  In this sequence, as an example of a control method for controlling the number of usable connections in accordance with the load value, the application server 120a inquires of the database server 110 about the load value, as in the processing from S304 to S312. A method of controlling the number of usable connections according to the obtained load value, and a control in which the database server 110 detects its own load value and disconnects the already established connection according to the detected load value The method was explained.

  In addition, the load detection unit 215A may periodically detect the load value of the database server 110 and periodically transmit the detected load value to the application server 120a through the communication control unit 290A. Then, when detecting that the load value has been notified through the communication control unit 290a, the load acquisition unit 210a may set the number of usable connections according to the notified load value. Note that the communication control unit 290A may transmit the load value to the plurality of application servers 120 substantially simultaneously, for example, in the form of broadcast, or may sequentially transmit the load value to the application server 120.

  In addition, the load acquisition unit 210a transmits a signal requesting a response to the database server 110, and the database server 110 is based on the time length from when the signal is transmitted until the response is received from the database server 110. The load value of the database server 110 may be acquired by specifying the load value. For example, the load acquisition unit 210a may specify a larger load value as the time length is longer. Note that the load acquisition unit 210a may acquire the load value of the database server 110 at an arbitrary timing. For example, the load acquisition unit 210a may acquire the load value of the database server 110 at any timing including the timing included in the period of accessing the database server 110, such as S322 to S336. Then, the connection control unit 220a may control the number of usable connections at an arbitrary timing.

  FIG. 4 shows an example of data stored in the connection number storage unit 230 in a table format. The connection number storage unit 230 stores a CPU usage rate, a memory usage rate, a data access rate, a network bandwidth usage rate, and a connection availability rate in association with each other. The CPU usage rate, memory usage rate, data access rate, and network bandwidth usage rate are examples of the load value of the computer in the present invention.

  The CPU usage rate indicates a load value of the CPU, and may be a ratio of the CPU execution time to the total time. The execution time of the CPU may be the time when all the instructions executed by the CPU are executed, or may be the execution time when the CPU executes only the instructions that provide the database function. As described above, the execution time of the CPU may not include the execution time when the CPU executes a command that provides a function other than the database function.

  The memory usage rate may be, for example, a usage amount of a main storage device (main memory) that can be directly accessed from the CPU. The memory usage rate may be a ratio of the used capacity to the total capacity of the main storage device. Note that the main storage device may be volatile or non-volatile.

  The data access rate may be an access amount to the auxiliary storage device (or secondary storage device). Specifically, the data access rate may be a data access rate. More specifically, the data access rate may be based on a transfer rate indicating the amount of data per unit time read from or written to the auxiliary storage device. For example, the data access rate may be a ratio of the transfer rate to the maximum transfer rate. The auxiliary storage device may be, for example, a magnetic disk such as a hard disk, a semiconductor memory, or the like.

  The data access rate may be an access amount for a specific disk volume. The specific disk volume here may be a disk volume in which a file storing data stored as a database is recorded, or a file used for operating as a database, for example, transaction information. It may be a disk volume in which files to be recorded are recorded. A disk volume includes a partition and a slice, and includes a physical volume and a logical volume.

  The network usage rate uses as an index value the amount of received data received from the outside through the network, the amount of transmitted data transmitted per unit time, or the amount of transmitted / received data indicating the total value of the received data amount and the transmitted data amount. Good. For example, the network usage rate may be a ratio of the received data amount, the transmitted data amount, or the transmitted / received data amount to the maximum data amount that can be transmitted / received by the network device.

  The connection availability rate may be a ratio of the number of currently available connections of the application server 120 to the maximum value of the number of connections that can be generated by the application server 120. The maximum value of the number of connections that can be generated by the application server 120 may be set in advance for each application server 120.

  Note that the current number of available connections of the application server 120 is not necessarily the number of connections currently generated. For example, the application server 120 may control to use only a smaller number of connections at the same time while holding a predetermined number of connections. For example, the application server 120 may limit the use of connections so that only 8 connections can be used simultaneously while holding 20 connections. In this case, the connection availability rate is 40%. Note that the application server 120 can also control the number of usable connections by disconnecting the connection. When the number of usable connections is controlled by disconnecting the connection in this way, the ratio of the number of connections currently generated to the maximum value of the number of connections that can be generated is the connection usable rate.

  Note that the resource usage in the present invention is the memory swapped to a recording medium such as a hard disk in addition to the CPU usage rate, memory usage rate, data access rate, and network bandwidth usage rate described with reference to FIG. It includes various resource usage such as the amount or swap amount indicating the amount of memory read from the recording medium. As described above, the connection number storage unit 230 stores the connection availability rate in association with the resource usage. Since the value obtained by multiplying the maximum number of connections that can be generated by the connection availability rate is the number of available connections, the connection control unit 220 associates the resource usage detected by the load detection unit 215A. By controlling the number of usable connections of the application server 120 by multiplying the connection usable rate stored in the connection number storage unit 230 by the maximum number of connections that can be generated by the application server 120 The number of usable connections is dynamically controlled according to the resource usage.

  FIG. 5 shows an example of the time evolution 510 of the CPU usage rate and the time evolution 510 of the number of usable connections. The CPU usage rate 500 of the database server 110 is 30% or less until the time t1, and therefore the connection availability rate is 100%. Therefore, when the application server 120 is allowed to establish 20 connections, the connection control unit 220 sets the number of usable connections to 20.

  When the CPU usage rate detected by the load detection unit 215A exceeds the first threshold 30% at time t1, the database server 110 transmits the CPU usage rate to the application server 120 through the communication control unit 290A. The load acquisition unit 210 acquires the CPU usage rate of the database server 110 through the communication control unit 290 and supplies the CPU usage rate to the connection control unit 220. Since the CPU usage rate is greater than 30% and 50% or less until time t2, the connection control unit 220 refers to the connection number storage unit 230 and determines that the connection availability rate should be 40%. Therefore, the connection control unit 220 reduces the usable number of connections by 12 to 8 pieces.

  When the CPU usage rate detected by the load detection unit 215A at time t2 exceeds the second threshold value 50%, which is larger than the first threshold value, the database server 110 sends the CPU usage rate to the application server 120 through the communication control unit 290A. Send. When the load acquisition unit 210 acquires the CPU usage rate from the database server 110, the connection control unit 220 refers to the data stored in the connection number storage unit 230 in the same manner as in the above control, and further determines the connection usable number. Reduce 6 to 2

  After that, when the CPU usage rate is larger than the second threshold value and transitions below the third threshold value 80% and it is detected that the CPU usage rate becomes equal to or lower than the second threshold value at time t3, the database server 110 passes the communication control unit 290A. The CPU usage rate is transmitted to the application server 120. When the load acquisition unit 210 acquires the CPU usage rate, the connection control unit 220 refers to the data stored in the connection number storage unit 230 in the same manner as the above control, and sets the CPU usage rate acquired by the load acquisition unit 210. Calculate the number of available connections. Specifically, the connection control unit 220 increases the usable number of connections by six to eight. When the CPU usage rate detected by the load detection unit 215A becomes equal to or less than the first threshold at time t4, the database server 110 transmits the CPU usage rate to the application server 120. Then, the connection control unit 220 refers to the data stored in the connection number storage unit 230 in the same manner as in the above control, and sets 20 as the number of usable connections according to the CPU usage rate acquired by the load acquisition unit 210. Calculate and set the number of usable connections to 20.

  In the example of this figure, for the purpose of preventing the description from becoming complicated, an example of the time evolution of the number of usable connections according to the CPU usage rate which is an example of the load value is shown. It goes without saying that 220 may control the number of usable connections in accordance with a load value other than the CPU usage rate, such as a memory usage rate, a data access rate, and a network bandwidth usage rate. For example, the connection control unit 220 calculates a connection average value obtained by weighting the connection availability rate stored in the connection number storage unit 230 corresponding to each resource usage amount with a predetermined weight for each resource usage amount. It may be a usable rate.

  As described in the above example, the database server 110 loads the database server 110 on the condition that the load detection unit 215A detects a load value exceeding the threshold stored in the connection number storage unit 230. The value may be sent to the application server 120. As described above, the first threshold value, the second threshold value, and the third threshold value are examples of the connection number decreasing load value in the present invention. Further, the first threshold value, the second threshold value, and the third threshold value also function as the connection number increasing load value in the present invention. The first threshold value and the second threshold value may be the connection number decreasing load value in the present invention, and the third threshold value may be the disconnection load value in the present invention.

  FIG. 6 shows an example of the increase / decrease amount of the number of usable connections under the control of the connection control unit 220. The control method of this figure is an example of a control method for adjusting the amount of increase / decrease in the number of available connections (or connection availability rate) with other application servers 120. In this case, the connection control unit 220A included in the database server 110 controls the number of available connections (or connection availability rate) of the plurality of application servers 120.

  As shown in FIG. 6, in the application servers 120a, b, and c, the number of usable connections is 8, 8, and 4, respectively, and the number of currently used connections is 4, 5, And two. Here, the number of connections currently in use may be the number of connections that are currently used at the same time, or the number of connections that have been used at the same time from the previous time to the present by a predetermined time width from now. It may be the maximum number of connections. The connection usage number detection unit 280A can calculate the number of currently used connections by specifying the connection used for communication with the application server 120.

  FIG. 6 shows an application server when the connection control unit 220A increases the total number of connections by 3 when the number of usable connections and the number of currently used connections are the values shown in FIG. An example of each increase amount of 120 is shown. When increasing the number of connections, the connection control unit 220A calculates, for each application server 120, a ratio of the number of currently used connections to the number of available connections (hereinafter referred to as a connection usage ratio). . Then, the connection control unit 220A increases the number of usable connections in a direction in which the connection usage ratio becomes equal among the plurality of application servers 120. In the example of FIG. 6, the connection control unit 220A increases the number of usable connections of the application servers 120a and 120b by 1 and 2, respectively, and does not change the number of usable connections of the application server 120c.

  On the other hand, when the total number of usable connections is decreased by three, the number of usable connections in the direction in which the connection usage ratio becomes equal among the plurality of application servers 120, as in the case of increasing the number of usable connections. Decrease. In the example of FIG. 6, the number of usable connections of the application servers 120a and 120c is decreased by 2 and 1, respectively, and the number of usable connections of the application server 120b is not changed. In this way, the connection control unit 220A controls the increase / decrease amount of the number of usable connections of the application server 120 to reduce the difference in connection usage ratio among the plurality of application servers 120.

  In this way, the connection control unit 220A adjusts the number of usable connections of each of the plurality of application servers 120 so that the connection usage ratio is equal among the plurality of application servers 120. According to such a control method, it is possible to reduce the probability that the connection usage ratio of the application server 120 becomes 100%, and it is possible to reduce the probability that the processing of the WEB server 130 is delayed or a timeout occurs. There is a case.

  In addition to the method of adjusting the number of available connections based on the connection usage ratio as in the above example, the connection control unit 220A can determine whether the number of available connections and the number of currently used connections are between The number of usable commissions of the application server 120 having a smaller difference may be increased more.

  Further, when the connection control unit 220A decreases the number of usable connections, the application server 120 having a larger connection usage ratio or an application having a smaller difference between the number of usable connections and the number of used connections. The number of usable connections of the server 120 may be reduced more preferentially. According to such a control method, for example, the application server 120 is less likely to increase the number of connections as the connection usage ratio increases. For this reason, it may be possible to balance the connection usage ratio among the plurality of application servers 120 or to effectively reduce the load value of the database server 110.

  FIG. 7 shows an example of data stored in the connection control unit 220. The connection control unit 220 associates the time when the number of usable connections is decreased or increased with the number of usable connections that are decreased or increased, and stores them as connection control history information. The connection control unit 220 stores the connection usage rate stored in the connection number storage unit 230 so that the load value of the database server 110 can be effectively controlled based on the stored connection control history information. Update dynamically.

  Specifically, the connection control history information shown in FIG. 7 decreases the number of available connections by 12 at the first time (10:30:15), and then the second time (10:30:50). Indicates that the number of usable connections is increased by 12. Accordingly, the connection control unit 220 reduces the load value of the database server 110 by reducing the number of usable connections by 12, and can restore the number of usable connections (for example, the CPU usage rate is 30). %), It can be determined that it took 35 seconds for the load value of the database server 110 to decrease. As described above, the connection control unit 220 can obtain the actual value of the control speed of the load value of the database server 110 based on the connection control history information.

  Therefore, the connection control unit 220 determines whether or not it is necessary to reduce the load value of the database server 110 faster based on the control speed of the load value indicated by the connection control history. When the connection control unit 220 determines that the load value needs to be reduced more quickly, the connection control unit 220 causes the connection number storage unit 230 to store a smaller connection availability rate. For example, the connection control unit 220 reduces the connection availability rate from 40% to 30% for a CPU usage rate that is greater than 30% and less than 50%.

  In this way, the connection control unit 220 stores a smaller connection usage rate in the connection number storage unit 230 as the time from the decrease in the number of usable connections to the increase in the number of usable connections is increased, for example. Also, the connection control unit 220 stores a smaller connection usage rate in the connection number storage unit 230 as the time from increasing the number of usable connections to decreasing the number of usable connections is shorter.

  In this manner, the connection control unit 220 dynamically adjusts the connection availability rate according to the load value control history. This may prevent the number of usable connections from being reduced more than necessary or prevent the decrease in the number of usable connections from being too small relative to the increase in the load value. . Further, when the number of application servers 120 increases, the increase / decrease amount of the number of usable connections per application server 120 may be small. By dynamically adjusting the connection availability according to the control history as described above, the number of available connections is automatically adjusted to an appropriate value even when the application server 120 is added to the computer system 100. There is a case.

  As described above, the connection control unit 220 provided in each of the application servers 120 controls the number of usable connections of each of the application servers 120, so that a specific application server 120 stops the service due to maintenance or the like. Even in such a case, the database server 110 may be able to operate without being aware of whether the application server 120 is alive or dead. The application server 120 may be able to autonomously adjust the number of usable connections according to the load value of the database server 110. Even when a new application server 120 is added, the number of usable connections is appropriately determined according to the load value of the database server 110 without notifying the database server 110 that the application server 120 has been added. May be adjusted.

  In the above description, the embodiment in which the application server 120 is connected to the database server 110 has been described. However, the connection in the present invention is established in various situations in addition to the above connection. Including various types of connections. For example, the connection in the present invention may be a connection established for the WEB server 130 to connect to the application server 120 in the above embodiment. For example, the connection of the present invention may be a connection between a process on the WEB server 130 and a process on the application server 120. The process referred to here may be a processing unit called a task or the like in some operating systems (OS). Further, the connection in the present invention may be a connection between different processes, or may be a connection between threads in the same process or different processes.

  The connection in the present invention may be an application layer connection. In addition, the connection in the present invention may be a TCP connection itself or a higher layer connection including a TCP connection. In addition, the connection in the present invention includes connections made by various protocols in addition to the TCP protocol.

  The connection in the present invention may be a connection between processes on different computers, or may be a connection between processes on the same computer. The connection in the present invention may be a connection between processes on the same virtual machine (virtual machine) or a connection between processes on different virtual machines. For example, the connection in the present invention may be a connection between a process operating on a first virtual machine and a process operating on a second virtual machine different from the first virtual machine. The virtual machine includes various virtual operating system environments called Java (registered trademark) VM, virtual machine monitor, and the like. Further, the connection in the present invention may be a connection between processes on a virtual machine operating on the same apparatus, and includes a connection between processes on a virtual machine operating on a different apparatus.

  FIG. 8 shows an example of a hardware configuration when the database server 110 and the application server 120 are each configured by an electronic information processing apparatus such as a computer. The database server 110 and the application server 120 include a CPU peripheral unit, an input / output unit, and a legacy input / output unit. The CPU peripheral section includes a CPU 1505, a RAM 1520, a graphic controller 1575, and a display device 1580 that are connected to each other by a host controller 1582. The input / output unit includes a communication interface 1530, a hard disk drive 1540, and a CD-ROM drive 1560 that are connected to the host controller 1582 by the input / output controller 1584. The legacy input / output unit includes a ROM 1510, a flexible disk drive 1550, and an input / output chip 1570 connected to the input / output controller 1584.

  The host controller 1582 connects the RAM 1520, the CPU 1505 that accesses the RAM 1520 at a high transfer rate, and the graphic controller 1575. The CPU 1505 operates based on programs stored in the ROM 1510 and the RAM 1520 to control each unit. The graphic controller 1575 acquires image data generated by the CPU 1505 or the like on a frame buffer provided in the RAM 1520 and displays the image data on the display device 1580. Alternatively, the graphic controller 1575 may include a frame buffer that stores image data generated by the CPU 1505 or the like.

  The input / output controller 1584 connects the host controller 1582 to the hard disk drive 1540, the communication interface 1530, and the CD-ROM drive 1560, which are relatively high-speed input / output devices. The hard disk drive 1540 stores programs and data used by the CPU 1505. The communication interface 1530 is connected to the network communication device 1598 to transmit / receive programs or data. The CD-ROM drive 1560 reads a program or data from the CD-ROM 1595 and provides it to the hard disk drive 1540 and the communication interface 1530 via the RAM 1520.

  The input / output controller 1584 is connected to the ROM 1510, the flexible disk drive 1550, and the relatively low-speed input / output device of the input / output chip 1570. The ROM 1510 stores a boot program executed when the database server 110 and the application server 120 are started up, a program depending on the hardware of the database server 110 and the application server 120, and the like. The flexible disk drive 1550 reads a program or data from the flexible disk 1590 and provides it to the hard disk drive 1540 and the communication interface 1530 via the RAM 1520. The input / output chip 1570 connects various input / output devices via the flexible disk drive 1550 or a parallel port, serial port, keyboard port, mouse port, and the like.

  A program executed by the CPU 1505 is stored in a recording medium such as the flexible disk 1590, the CD-ROM 1595, or an IC card and provided by the user. The program stored in the recording medium may be compressed or uncompressed. The program is installed in the hard disk drive 1540 from the recording medium, read into the RAM 1520, and executed by the CPU 1505. The program executed by the CPU 1505 uses the database server 110 as the connection establishment unit 200A, the load detection unit 215A, the connection control unit 220A, the connection number storage unit 230A, and the connection information storage unit 240A described with reference to FIGS. And the communication control unit 290A, the application server 120 is connected to the connection establishment unit 200, the load acquisition unit 210, the connection control unit 220, the connection number storage unit 230, and the connection information storage described with reference to FIGS. Unit 240, service utilization unit 250, and communication control unit 290.

  The program shown above may be stored in an external storage medium. As the storage medium, in addition to the flexible disk 1590 and the CD-ROM 1595, an optical recording medium such as a DVD or PD, a magneto-optical recording medium such as an MD, a tape medium, a semiconductor memory such as an IC card, or the like can be used. Further, a storage device such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium to provide a radiation imaging system as a program via the network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

It is a figure which shows an example of the utilization environment of the computer system 100 which concerns on one Embodiment. It is a figure which shows an example of the block configuration of the database server 110 and the application server 120. It is a figure which shows an example of the operation | movement sequence of the WEB server 130, the application server 120, and the database server 110. It is a figure which shows an example of the data which the connection number storage part 230 has stored in the table format. It is a figure which shows an example of the time development of CPU utilization, and the time development of the number of usable connections. 5 is a diagram illustrating an example of an increase / decrease amount of usable connections under the control of a connection control unit 220. FIG. It is a figure which shows an example of the data which the connection control part 220 has memorize | stored. It is a figure which shows an example of each hardware constitutions of the database server 110 and the application server 120.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Computer system 110 Database server 120 Application server 130 WEB server 140 Load balancer 150 Communication line 160 Client terminal 200 Connection establishment part 210 Load acquisition part 215 Load detection part 220 Connection control part 230 Connection number storage part 240 Connection information storage part 250 Service use Unit 255 service providing unit 280 connection usage number detecting unit 290 communication control unit 500 CPU usage rate 510 time development 1505 CPU
1510 ROM
1520 RAM
1530 Communication interface 1540 Hard disk drive 1550 Flexible disk drive 1560 CD-ROM drive 1570 Input / output chip 1575 Graphic controller 1580 Display device 1582 Host controller 1584 Input / output controller 1590 Flexible disk 1595 CD-ROM
1598 Network communication device

Claims (20)

A service providing unit provided in the service providing apparatus for providing a service;
A service using unit that is provided in a service using device different from the service providing device and uses a service provided by the service providing unit;
A connection establishing unit that is provided in each of the service providing device and the service using device, and in which the service using unit establishes in advance a plurality of connections for communicating with the service providing unit;
A load detection unit that is provided in the service providing device and detects a load value of a computer operating as the service providing device ;
A load acquisition unit that is provided in the service use device and acquires the load value detected by the load detection unit from the service providing device;
By disconnecting the connection established by the connection establishment unit when the load value acquired by the load acquisition unit is greater than a predetermined connection number reduction load value provided in the service utilization device, A computer system comprising: a connection control unit that reduces a number of connections that can be used by the service using unit among connections established by the connection establishing unit. Load value the load detecting unit detects the amount of resources that the computer has, and, a computer system according to claim 1 wherein the service providing unit comprises at least one length of time required to respond to an external . The computer system according to claim 2 , wherein the usage amount of the resource includes a usage rate of a CPU included in the computer. A connection number storage unit that is provided in the service utilization device and stores a smaller number of usable connections in association with the larger load value;
The connection control unit, the number of connections that can be the use of claim 1, wherein the connection number storage unit in association with the load value the load acquisition unit has acquired to control the number of connections that contain 4. The computer system according to any one of 3 . The connection control unit uses the load control unit when the load value acquired by the load acquisition unit is less than or equal to a predetermined connection number increase load value after reducing the number of usable connections. computer system according to any one of claims 1 to 4 to increase the number of connections that can. A plurality of the service using devices are provided,
The plurality of connection establishment units provided in each of the plurality of service use devices may include a plurality of connection between each of the plurality of service use units provided in each of the plurality of service use devices and the service providing unit. Establish each connection,
Wherein each of the plurality of the connection control unit provided for each of the plurality of service using apparatus, when the load value the load acquisition unit has acquired is larger than the number of connections decreases load value, the plurality of connection establishing unit The computer system according to any one of claims 1 to 5 , wherein the number of connections that can be used by each of the plurality of service using units is reduced by disconnecting connections established by each of the above . The service providing device is a database server that provides data to the external store data,
The service use unit, a computer system according to any one of claims 1 to 6 that utilizes data which the database server provides. The service using apparatus, a computer system according to <br/> claim 7 which is an application server that the database server provides a service to the outside by utilizing the data provided. The connection control unit provided in each of the plurality of application servers is established by the connection establishment unit when the load value acquired by the load acquisition unit becomes larger than the connection number reduction load value . The computer system according to claim 8 , wherein the number of connections that can be used by each of the service using units provided in each of the plurality of application servers is reduced by disconnecting the connection . A control method for controlling a computer system including a service using unit that uses a service provided by a service providing unit that provides a service provided in a service providing device ,
A service establishing unit provided in each of the service providing apparatus and the service using apparatus includes a plurality of connections for the service using unit provided in a service using apparatus different from the service providing apparatus to communicate with the service providing unit. A pre-established connection establishment stage;
A load detecting unit provided in the service providing apparatus detects a load value of a computer operating as the service providing apparatus ; and
A load acquisition unit provided in the service utilization device acquires a load value detected in the load detection step from the service providing device; and
The connection control unit provided in the service using device determines the connection established in the connection establishment step when the load value acquired in the load acquisition step is larger than a predetermined connection number reduction load value. A control method comprising: a connection control step of reducing the number of connections that can be used by the service using unit among the connections established in the connection establishment step by disconnecting .   A service provider that provides services;
  A plurality of service using units provided in each of a plurality of service using devices, and using a service provided by the service providing unit;
  Between each of the plurality of service using units and the service providing unit, a connection establishing unit that establishes in advance a plurality of connections for each of the plurality of service using units to communicate with the service providing unit, and
  A load detection unit for detecting a load value of a computer operating as the service providing unit;
  Of the connections that can be used by each of the plurality of service utilization units, a connection usage number detection unit that detects the number of connections currently used by each of the plurality of service utilization units;
  When the load value detected by the load detecting unit becomes larger than a predetermined connection number decreasing load value, each of the plurality of service using units among the connections established by the connection establishing unit is used. A connection controller that reduces the number of connections each
With
  The load value detected by the load detection unit includes at least one of a resource usage amount of the computer and a time length required for the service providing unit to respond to the outside, and the resource usage amount is: Including the usage rate of the CPU of the computer,
  The connection control unit, when the load value detected by the load detection unit is greater than the load reduction load value, the number of connections detected by the connection usage number detection unit and each of the plurality of service usage units Based on the number of connections that can be used, the ratio of the number of connections used by each of the plurality of service using units to the number of connections that can be used by each of the plurality of service using units is the plurality of connections. Reducing the number of connections that can be used by at least one of the plurality of service utilization units in the same direction between the service utilization units of
  The service providing unit, the load detecting unit, the connection usage number detecting unit, and the connection control unit are provided in a service providing device,
  The connection establishment unit is provided in each of the plurality of service using devices and the service providing device.
Computer system.   The connection control unit reduces the number of connections that can be used, and then reduces the number of connections used when the load value detected by the load detection unit becomes smaller than a predetermined connection number increase load value. Based on the number of connections detected by the detection unit and the number of connections that can be used by each of the plurality of service using units, the plurality of connections with respect to the number of connections that can be used by each of the plurality of service using units. Increase the number of connections that can be used by at least one of the plurality of service utilization units in a direction in which the ratio of the number of connections used by each service utilization unit becomes equal among the plurality of service utilization units Make
The computer system according to claim 11.   A service provider that provides services;
  A plurality of service using units provided in each of a plurality of service using devices, and using a service provided by the service providing unit;
  Between each of the plurality of service using units and the service providing unit, a connection establishing unit that establishes in advance a plurality of connections for each of the plurality of service using units to communicate with the service providing unit, and
  A load detection unit for detecting a load value of a computer operating as the service providing unit;
  Of the connections that can be used by each of the plurality of service utilization units, a connection usage number detection unit that detects the number of connections currently used by each of the plurality of service utilization units;
  When the load value detected by the load detecting unit becomes larger than a predetermined connection number decreasing load value, each of the plurality of service using units among the connections established by the connection establishing unit is used. A connection controller that reduces the number of connections each
With
  The load value detected by the load detection unit includes at least one of a resource usage amount of the computer and a time length required for the service providing unit to respond to the outside, and the resource usage amount is: Including the usage rate of the CPU of the computer,
  The connection control unit reduces the number of connections that can be used, and then reduces the number of connections used when the load value detected by the load detection unit becomes smaller than a predetermined connection number increase load value. Based on the number of connections detected by the detection unit and the number of connections that can be used by each of the plurality of service using units, the plurality of connections with respect to the number of connections that can be used by each of the plurality of service using units. Increase the number of connections that can be used by at least one of the plurality of service utilization units in a direction in which the ratio of the number of connections used by each service utilization unit becomes equal among the plurality of service utilization units Let
  The service providing unit, the load detecting unit, the connection usage number detecting unit, and the connection control unit are provided in a service providing device,
  The connection establishment unit is provided in each of the plurality of service using devices and the service providing device.
Computer system.   The service providing apparatus is a database server that stores data and provides the data to the outside.
  The plurality of service using units use data provided by the database server.
The computer system according to any one of claims 11 to 13.   The plurality of service use devices are application servers that provide services to the outside using data provided by the database server.
The computer system according to claim 14.   The connection control unit disconnects the connection established by the connection establishment unit when the load value detected by the load detection unit becomes larger than the connection number reduction load value, thereby using the plurality of services. Reduce the number of connections each part can use
The computer system according to any one of claims 11 to 15.   The connection control unit, when the load value detected by the load detection unit becomes larger than the connection number reduction load value, sends a command to the plurality of service using devices to reduce the number of connections that can be used. By transmitting, the number of connections that each of the plurality of service using units can use is reduced.
The computer system according to any one of claims 11 to 15. A service using device that uses a service provided by a service providing device, different from the service providing device ,
A service using unit that uses a service provided by the service providing device;
A connection establishment unit that establishes in advance a plurality of connections for the service using device to communicate with the service providing device;
A load acquisition unit for acquiring a load value of the service providing device;
When the load value acquired by the load acquisition unit is greater than a predetermined connection number reduction load value, the connection established by the connection establishment unit is disconnected by disconnecting the connection established by the connection establishment unit. A connection control unit that reduces the number of connections that can be used by the service using unit ,
The service providing apparatus includes:
A connection establishment unit that establishes the plurality of connections in advance with the service using device;
A service providing unit for providing the service;
A load detection unit for detecting a load value of a computer operating as the service providing device;
Have
The service using unit uses a service provided by the service providing unit,
The connection establishment unit pre-establishes the plurality of connections for the service using unit to communicate with the service providing unit,
The service use device , wherein the load acquisition unit acquires the load value detected by the load detection unit from the service providing device.   The program for functioning a computer as a service utilization apparatus of Claim 18. A control method for controlling a service using device different from the service providing device using a service provided by a service providing device ,
A connection establishment step in which a service utilization unit provided in the service utilization device and utilizing the service establishes a plurality of connections for communicating with the service provision device;
A load acquisition unit provided in the service using device acquires a load value of the service providing device; and
Established in the connection establishment stage by disconnecting the connection established in the connection establishment stage when the load value obtained in the load acquisition stage exceeds a predetermined connection number reduction load value A connection control step for reducing the number of connections that can be used by the service using unit among the connections ,
The service providing apparatus includes:
A connection establishment unit that establishes the plurality of connections in advance with the service using device;
A service providing unit for providing the service;
A load detection unit for detecting a load value of a computer operating as the service providing device;
Have
In the connection establishment step, the service using unit establishes the plurality of connections for communicating with the service providing unit in advance,
The load acquisition step is a control method in which the load acquisition unit acquires the load value detected by the load detection unit from the service providing apparatus .

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