JP2010122818A - Computer system and computer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a computer system capable of preventing the concentration of loads into a command distribution destination while reducing the loads of a command distribution destination node, and thereby capable of performing optimum load balancing. <P>SOLUTION: The computer system includes the command distribution source node 1 for distributing commands and the command distribution destination node 2 for receiving and executing the commands. In the computer system, the command distribution destination node 2 does not perform operation for measuring the loads of the node 2 itself and the command distribution source node 1 detects the loads of the command distribution destination node 2. The command distribution source node 1 controls the distribution of commands to the command distribution destination node 2 according to the detected loads. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a computer system, and more particularly to a computer system configured to distribute commands from one node to another node.

  In a distributed processing system including a plurality of nodes (for example, computers), in order to process one task on a plurality of nodes, control is performed such that a command is transmitted from one node to another node and executed. May be. Such a computer system is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-328127 (Patent Document 1).

  In the distributed processing system of Patent Document 1, a command is sent from a manager machine to an agent machine to execute a task. At this time, depending on the contents of the business, a command request such as distributing a command to a plurality of nodes at the same time or selecting and distributing an arbitrary node from the plurality of nodes may occur. In order to meet such a demand, the distributed processing system of Patent Document 1 has a special device for easily performing command transmission and execution from a manager machine to a plurality of agent machines.

  However, in a distributed processing system that sends a command from one node to another, the command is distributed to a node that is temporarily in a high load state due to the concentration of business processing. The problem of causing delays can occur.

  One method for solving the problem of load concentration is a method of appropriately switching the priority of command distribution destination selection. Such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 6-119282 (Patent Document 2).

  Another method for solving the load concentration problem is a method of detecting the load of the command distribution destination and determining the command distribution destination according to the detection result. Such a method is disclosed in, for example, Japanese Patent Laid-Open No. 11-250023 (Patent Document 3). In the distributed processing system disclosed in this document, each processing apparatus measures its own load level and transmits it to the processing distributor. Each processing apparatus determines whether or not to notify the processing distributor of the load level at each time according to the value of the load level and the elapsed time since the previous notification of the load level. On the other hand, the processing distributor estimates the current load level of each processing apparatus with a range by using the load level sent in the past and the elapsed time from that point. The processing distributor performs load distribution processing according to the estimated value. Other methods for detecting the load at each node are also disclosed in JP-A-11-143838 (Patent Document 4) and JP-A-2002-7144 (Patent Document 5).

However, in the configuration in which the node that executes the command itself detects the load, a load for load detection is applied to each node, and thus there is a problem that the work of each node that executes the command is compressed.
JP 11-328127 A JP-A-6-119282 Japanese Patent Laid-Open No. 11-250023 Japanese Patent Laid-Open No. 11-143838 JP 2002-7144 A

  Accordingly, an object of the present invention is to provide a computer system capable of reducing the load on a command distribution destination node while preventing concentration of the load on the command distribution destination and thereby performing optimum load distribution. .

  The computer system of the present invention includes a first node for distributing a command and a second node for receiving and executing the command. In the computer system, the first node detects the load of the second node without the second node performing an operation of measuring its own load. The first node is configured to control delivery of the command to the second node according to the detected load.

  According to the present invention, it is possible to provide a computer system capable of reducing the load on a command distribution destination node while preventing the load from being concentrated on the command distribution destination and thereby performing optimal load distribution.

(First embodiment)
Referring to FIG. 1, the computer system of the first embodiment includes a command distribution source node 1, a command distribution destination node 2, and a network 3 that connects the command distribution source node 1 and the command distribution destination node 2. In FIG. 1, three command distribution destination nodes 2 are illustrated, and when necessary, they are distinguished by being referred to by reference numerals 2A, 2B, and 2C. The command distribution source node 1 distributes the command to the command distribution destination node 2, and causes the command distribution destination node 2 to perform a desired process. Examples of the command to be distributed include a file operation command (file initialization, deletion, etc.), a data collection / inquiry command, a command for instructing start of batch processing or operation change, and the like. A terminal 11 is connected to the command distribution source node 1, and the user can cause the command distribution source node 1 to perform an operation of distributing a desired command to the command distribution destination node 2 by operating the terminal 11. it can.

  FIG. 2 is a block diagram illustrating an example of the configuration of the command distribution source node 1 and the command distribution destination node 2. The command distribution source node 1 includes an application program 12, a command reception unit 13, a command queue 15, a queue management unit 16, a load evaluation unit 17, and a command distribution unit 18. Although only one command queue 15 is illustrated in FIG. 1, actually, the command queue 15 is prepared for each command distribution destination node 2. That is, when there are three command distribution destination nodes 2, three command queues 15 are prepared in the command distribution source node 1. The command receiving means 13, the command queue 15, the queue management means 16, the load evaluation means 17, and the command distribution means 18 are implemented in the command distribution source node 1 in any form of software, hardware, and a combination thereof. May be.

  In addition, a command attribute information file 14 and an execution result list 19 are prepared in the storage device of the command distribution source node 1. The command attribute information file 14 is a file that stores information (that is, command attribute information) for defining operation attributes and the like for each command in advance. The execution result list 19 records the execution time and execution result of the command executed by the command delivery destination node 2 in response to the instruction from the command delivery source node 1.

  There can be a plurality of command distribution destination nodes 2, each including at least a command execution means 21 and a command processing program 22. The command distribution destination node 2 may be configured to execute business processing other than the command processing program 22. The command execution means 21 may be implemented in the command distribution source node 1 in any form of software, hardware, and a combination thereof.

The command distribution source node 1 and the command distribution destination node 2 generally operate as follows:
When the command receiving means 13 of the command distribution source node 1 receives a command distribution request including a command text and its destination information from the terminal 11 or the application program 12, the correspondence of the command distribution request destination information or command attribute information file 14 is received. The command distribution destination node 2 is determined based on the command attribute information to be registered, and the command distribution request is registered in the command queue 15 corresponding to the command distribution destination node 2.

  The queue management means 16 monitors the command queue 15, and when a command distribution request is registered in the command queue 15, retrieves it one by one, checks the load status of the command distribution destination node 2 by the load evaluation means 17, When it is determined that the resulting load is high, after waiting for a predetermined time, if it is not determined that the load is high, the command distribution means 18 is immediately activated to distribute the command to the command distribution destination node 2. .

  The load evaluation means 17 refers to the execution result list 19 and, for all commands distributed and executed to the command distribution destination node 2 between the current time and a predetermined time before, the actual command execution time and the command Information on the standard execution time is acquired, and if the actual command execution time exceeds the standard execution time by a predetermined amount or more, it is determined that the load is high.

  The command distribution means 18 distributes the command text included in the command distribution request to the command distribution destination node 2, and the standard execution time of the command indicated in the command distribution request or the command attribute information in the execution result list 19, and the command Record the delivery time. Furthermore, the command execution result is received from the command distribution destination node 2, the received execution result and the received time are registered in the execution result list 19, and the execution result is returned when the command distribution request instructs the return of the execution result. Is returned to the terminal 11 or the application program 12.

  The command execution unit 21 receives the command distributed by the command distribution unit 18 and executes the corresponding command processing program 22. When the command execution ends, the command execution means 21 returns the execution result to the command distribution means 18.

Next, the operation of the computer system of this embodiment will be described in detail with reference to FIGS.
FIG. 3 shows an example of the structure of the execution result list 19 of FIG. 2 and an example of recording in the execution result list 19. The execution result list 19 is prepared for each command distribution destination node 2, and includes an item of the command name 31, an item of the standard execution time 32 that is a standard execution time of the command, and a start time that is the execution start time of the command. 33 items, an item of the end time 34 that is the execution end time of the command, and an item of the execution result 35 are included. One entry of the execution result list 19 is assigned to one command, and information on these items is described in each entry. In FIG. 3, reference numerals 41 to 47 indicate entries.

  On the other hand, FIG. 4 shows an example of the structure of a command distribution request issued from the terminal 11 or the application program 12. The command distribution request is to wait for the destination information 51 indicating one or more command distribution destination nodes 2 directly or indirectly and when the load of the command distribution destination node 2 is high (“waiting is possible”) or an error. Is returned ("error") or forcibly executed regardless of the load status ("forced execution"), a standard execution time 53 indicating the standard execution time of the command, and command execution Result return method information 54 indicating whether or not results need to be returned, and command text 55 including command parameters specifying a command name, command execution conditions, and the like. However, the destination information 51, the operation attribute 52, the standard execution time 53, and the result return method information 54 can be defined in advance for each command name and registered in the command attribute information file 14, and registered in the command attribute information file 14. These items can be omitted in the command distribution request.

  When receiving a command distribution request from the terminal 11 or the application program 12, the command receiving unit 13 stores some or all items of the command distribution request destination information 51, the operation attribute 52, the standard execution time 53, and the result return method information 54. If omitted, the information of the omitted item in the command attribute information corresponding to the command name in the command text 55 is acquired from the command attribute information file 14 and set in the corresponding item of the command distribution request. Next, the command receiving unit 13 determines the command distribution destination node 2 based on the destination information 51. Further, when the operation attribute 52 of the command distribution request is “waiting is possible”, the command receiving means 13 registers the command distribution request in the command queue 15 corresponding to the command distribution destination node 2. When the operation attribute 52 is “error”, the command receiving unit 13 checks the load status of the command distribution destination node 2 by the load evaluation unit 17, and when the load is high, the command receiving unit 13 gives an error to the terminal 11 or the application program 12. If not, the command distribution unit 18 is activated, and a command distribution request is delivered to the command distribution unit 18. When the operation attribute 52 is “forced execution”, the command receiving unit 13 unconditionally activates the command distribution unit 18 and passes the command distribution request to the command distribution unit 18.

  The queue management means 16 monitors the command queue 15, and when a command delivery request is registered in the command queue 15, takes it out and examines the load status of the command delivery destination node 2 by the load evaluation means 17. As a result of the examination, if it is determined that the load is high, the queue management unit 16 activates the command distribution unit 18 after waiting for a predetermined time, and passes the command distribution request to the command distribution unit 18. On the other hand, if it is not determined that the load is high as a result of examining the load status, the queue management unit 16 immediately activates the command distribution unit 18 and passes the command distribution request to the command distribution unit 18. When a plurality of command distribution requests are registered in the command queue 15 at the same time, the queue management means 16 takes out one by one from the oldest registration order, performs the above-described processing, and activates the command distribution means 18 Then, the next command distribution request is taken out.

  The load evaluation unit 17 has a function of examining the load status of the command distribution destination node 2. In this embodiment, the load status of the command delivery destination node 2 is determined based on the command execution time that is the time actually delivered to the command delivery destination node 2 and actually executed for each command. More specifically, in this embodiment, the load evaluation unit 17 checks the load status of each command distribution destination node 2 as follows. The load evaluation means 17 refers to the execution result list 19 and executes the actual command execution time and standard execution of the command for each command distributed and executed to the command distribution destination node 2 between the current time and a predetermined time before. Get time 32. Here, the command execution time is calculated from the start time 33 and the end time 34 of the command execution. Furthermore, the load evaluation means 17 determines that the load is high when the actual command execution time exceeds the standard execution time 32 by a predetermined amount or more.

  Upon receiving the command distribution request, the command distribution means 18 distributes the command text 55 to the command distribution destination node 2, creates a new entry in the execution result list 19, and adds the command name 31 of the created entry from the command text 55. The extracted command name is recorded in the standard execution time 32 as the standard delivery time 53 of the command delivery request, and the command delivery time is recorded as the start time 33. In the command distribution destination node 2, the command execution means 21 receives the command and executes the corresponding command processing program 22. When the command execution is completed, the command execution means 21 returns the command execution result to the command distribution means 18. The command distribution means 18 records the time when the execution result is received as the end time 34 of the execution result list 19, records the contents of the execution result returned as the execution result 35 of the execution result list 19, and the result of the command distribution request If the return method information 54 instructs to return the execution result, the returned execution result is returned to the terminal 11 or the application program 12. The time at which the command execution means 21 receives the command at the command distribution destination node 2 is recorded in the execution result list 19 as the start time 33, and the command processing program 22 is terminated and the execution result is returned to the command distribution means 18. The time when this is done may be recorded in the execution result list 19 as the end time 34. In this case, the command execution means 21 gives the command distribution means 18 when the command is completed, in addition to the command execution result, the time when the command execution means 21 received the command, and the command processing program 22 ends and the command distribution means 18 Returns the time when the execution result is returned. The command distribution means 18 records these returned times as a start time 33 and an end time 34, respectively.

  The operation for distributing the command differs depending on the content of the operation attribute 52 described in the command distribution request. Hereinafter, a command distribution operation depending on the contents of the operation attribute 52 will be described in detail.

(1) When the operation attribute is “waiting”:
For example, when the command receiving means 13 of the command distribution source node 1 receives a command distribution request from the application program 12 where the destination information 51 is the command distribution destination node 2A and the operation attribute 52 is “waiting”, the command reception The means 13 registers a command distribution request in the command queue 15 corresponding to the command distribution destination node 2A. At this time, if the standard execution time 53 and the result return method information 54 are not specified in the command distribution request, the corresponding information is acquired from the command attribute information file 14 and set in the command distribution request.

  When the queue management unit 16 takes out the command distribution request from the command queue 15 of the command distribution destination node 2A, the queue management unit 16 calls the load evaluation unit 17. The load evaluation unit 17 refers to the execution result list 19 corresponding to the command distribution destination node 2A, and evaluates the load of the command distribution destination node 2A according to the operation of FIG.

  More specifically, as shown in FIG. 5, the load evaluation unit 17 obtains a reference time by subtracting a predefined verification time from the current time (S01), and the latest entry in the execution result list 19 is obtained. The entries from the entry time (entry 47 in FIG. 3) to the reference time are sequentially referred to (S02 to S05). For each entry, first, the start time 33 in the execution result list 19 is compared with a reference time (for example, 10:05:00), and if the reference time is later on the time axis than the start time, the execution result The reference of the list 19 is terminated (NO in S03). Otherwise, the command execution time is obtained by subtracting the start time 33 from the end time 34, and the command execution time is compared with the standard execution time 32, so that the excess time (the portion of the execution time that exceeds the standard execution time 32). (S04). When the reference of the target entry in the execution result list 19 is completed, the sum of the excess times is compared with a predefined reference value (S08). If the sum of the excess times is larger, the high load flag is set to ON (S09). Otherwise, the high load flag is set to OFF (S10), and the queue management means 16 is set with the high load flag. return.

  Next, when the high load flag returned from the load evaluation unit 17 is ON, the queue management unit 16 waits for a predetermined time, and after waiting, the command distribution unit 18 is started and the command distribution unit 18 is activated. Pass the command distribution request. When the high load flag returned from the load evaluation unit 17 is OFF, the queue management unit 16 immediately activates the command distribution unit 18 and passes the command distribution request to the command distribution unit 18.

  Note that the load evaluation of the command distribution destination node 2A is performed by the load evaluation means 17 provided in the command distribution source node 1. The command distribution destination node 2A does not perform an operation for measuring its own load. This is because an extra load is not applied to the command distribution destination node 2A. The operation of measuring the load itself places a load on the command distribution destination node 2A. Therefore, in the computer system of this embodiment, the load is evaluated by the load evaluation unit 17 provided in the command distribution source node 1, and the load on the command distribution destination node 2A is reduced.

  Upon receiving the command distribution request, the command distribution means 18 distributes the command text 55 included in the command distribution request to the command distribution destination node 2A and creates a new entry in the execution result list 19 corresponding to the command distribution destination node 2A. Then, the command name extracted from the command text 55 of the command distribution request is set as the command name 31, the standard execution time 53 of the command distribution request is set as the standard execution time 32, and the command distribution time is recorded at the start time 33. To do. In the command delivery destination node 2A, the command execution means 21 receives the command text 55 and executes the corresponding command processing program 22. When the command execution is completed, the command execution means 21 returns the command execution result to the command distribution means 18. The command distribution means 18 records the time when the execution result is received at the end time 34 of the entry created at the time of command distribution in the execution result list 19, and the contents of the execution result returned to the execution result 35 in the execution result list 19 are recorded. Record. Furthermore, when the return of execution results is instructed in the result return method information 54 of the command distribution request, the returned execution results are returned to the application program 12.

(2) When the operation attribute is “error”:
Next, for example, the operation when the command receiving means 13 of the command distribution source node 1 receives from the application program 12 a command distribution request in which the destination information 51 is the command distribution destination node 2A and the operation attribute 52 is “error”. explain. The command receiving unit 13 obtains and sets values from the command attribute information file 14 for items that are omitted from the command distribution request items, and then calls the load evaluation unit 17 to check the load status of the command distribution destination node 2A. . The operation of the load evaluation unit 17 is the same as the example in the case where the operation attribute 52 is “waiting”. If the high load flag returned from the load evaluation unit 17 is ON, the command reception unit 13 returns an error to the application program 12. If the high load flag returned from the load evaluation unit 17 is OFF, the command reception unit 13 activates the command distribution unit 18 and passes the command distribution request to the command distribution unit 18. The command distribution means 18 performs command distribution to the command distribution destination node 2A and recording to the execution result list 19 in the same manner as in the case where the operation attribute 52 is “waiting is possible”.

(3) When the operation attribute is “forced execution”:
Next, for example, when the command receiving means 13 of the command distribution source node 1 receives a command distribution request from the application program 12, the destination information 51 is the command distribution destination node 2A, and the operation attribute 52 is “forced execution”. explain. The command receiving means 13 obtains and sets values from the command attribute information file 14 for the omitted command delivery request items, and then unconditionally activates the command delivery means 18 and sends a command to the command delivery means 18. Deliver the delivery request. The command distribution means 18 performs command distribution to the command distribution destination node 2A and recording to the execution result list 19 in the same manner as in the case where the operation attribute 52 is “waiting is possible”.

  The computer system of this embodiment has the following two advantages. The first advantage is that when a command is distributed to the command distribution destination node 2 that is temporarily in a high load state due to the concentration of the business process, the business process is performed without pressing the resources of the corresponding node. It can be improved. This advantage is due to the fact that the computer system is configured so that extra load is not generated in the command distribution destination node 2 by detecting and waiting for the load in the command distribution source node 1.

  The second advantage is that the operation attributes are forcibly executed regardless of the load status of the command distribution destination node, and an error is returned without waiting if the load is high. Therefore, the operation according to the nature of the command is possible. Furthermore, even when these operation attribute commands are executed, the execution results are recorded in the execution result list 19, so that the load status can be determined more accurately by the execution result list 19.

(Second Embodiment)
FIG. 6 is a block diagram showing a configuration of a computer system according to the second embodiment of this invention. The configuration of the computer system of the second embodiment is generally the same as that of the computer system of the first embodiment. The difference is that a standard execution time calculation means 20 is added to the command distribution source node 1. The standard execution time calculation means 20 has a function of calculating the standard execution time for each command name based on the past actual execution time of the command of each command name and registering it in the command attribute information file 14. Yes.

  In order to enable the standard execution time calculation means 20 to calculate the standard execution time, the structure of the execution result list 19 is different from that of the first embodiment in the second embodiment. FIG. 7 is an example of the structure of the execution result list 19 in the second embodiment. Referring to FIG. 7, the execution result list 19 includes a command name item 31, a standard execution time item 32, a start time item 33, an end time item 34, and an execution result item 35. 36. The flag 36 is used to designate which command start time 33 and end time 34 are used for calculation of the standard execution time by the standard execution time calculation means 20. As will be described later, a command whose flag 36 is ON is not used for calculating the standard execution time.

  Below, operation | movement of the computer system of 2nd Embodiment is demonstrated. The operations of the command reception unit 13, the queue management unit 16, the command distribution unit 18, and the command execution unit 21 are the same as those in the first embodiment (FIG. 1). Therefore, hereinafter, operations of the load evaluation unit 17 and the standard execution time calculation unit 20 will be described.

  When called from the command receiving means 13 or the queue management means 16, the load evaluation means 17 evaluates the load of each command distribution destination node 2. Specifically, the load evaluation means 17 refers to the execution result list 19 and executes the actual command for all commands distributed and executed to the command distribution destination node 2 between the current time and a predetermined time before. The command execution time and the standard execution time 32 are acquired. The command execution time is calculated from the start time 33 and end time 34 of execution of each command. Further, the load evaluation means 17 obtains the excess time by comparing the command execution time with the standard execution time 32. When the excess time is calculated for all the commands distributed and executed to the command distribution destination node 2 between the current time and a predetermined time before, the load evaluation means 17 is defined in advance as the sum of the calculated excess times. Compared with the reference value, if the sum of the excess times is larger, it is determined that the load of the command distribution destination node 2 is high.

  When determining that the load of the command distribution destination node 2 is high, the load evaluating means 17 turns on the flags 36 of all commands distributed and executed to the command distribution destination node 2 between the current time and a predetermined time before. At the same time, the high load flag is set to ON and returned to the command receiving means 13 or the queue management means 16. As a result, when a command is processed in a state where the load of the command distribution destination node 2 is high, the flag 36 corresponding to the command is set to ON and excluded from the calculation of the standard execution time.

  On the other hand, when determining that the load of the command distribution destination node 2 is not high, the load evaluation unit 17 sets the high load flag to OFF and returns the high load flag to the queue management unit 16.

  The standard execution time calculation means 20 calculates a standard execution time for a specific command or all commands when activated by an instruction from a user or at a predetermined timing. Specifically, the standard execution time calculation means 20 acquires the actual command execution time from the execution result list 19 for the command to be calculated. The command execution time is calculated from the command execution start time 33 and end time 34. Further, the standard execution time calculation means 20 calculates the standard execution time of the command based on the actual command execution time, and registers the calculated standard execution time in the command attribute information file 14. However, a command for which the flag 36 of the execution result list 19 is set to ON and a command whose actual execution time exceeds the standard execution time 32 of the execution result list 19 by a predetermined calculation reference value or more are standard. It is not used to calculate execution time.

  Thus, in this embodiment, the standard execution time is calculated by the standard execution time calculation means 20 and registered in the command attribute information file 14. In such a configuration, since the load of each command distribution destination node 2 is evaluated based on the standard execution time calculated in accordance with the actual command execution time, the load of each command distribution destination node 2 is more appropriately set. Can be evaluated. At this time, the standard execution time can be appropriately calculated by excluding commands executed in a state where the load of the command distribution destination node 2 is high from the calculation of the standard execution time.

FIG. 1 is a block diagram showing a configuration of a computer system according to the first embodiment of this invention. FIG. 2 is a block diagram showing a configuration of a command distribution source node and a command distribution destination node of the computer system of FIG. FIG. 3 is a table showing the contents of the execution result list in the first embodiment. FIG. 4 shows an example of the contents of the command distribution request. FIG. 5 is a flowchart illustrating an example of a procedure in which the load evaluation unit of the command distribution source node detects the load of the command distribution destination node. FIG. 6 is a block diagram showing a configuration of a computer system according to the second embodiment of this invention. FIG. 7 is a table showing the contents of the execution result list in the second embodiment.

Explanation of symbols

1: Command distribution source node 2, 2A to 2C: Command distribution destination node 3: Network 11: Terminal 12: Application program 13: Command reception means 14: Command attribute information file 15: Command queue 16: Queue management means 17: Load evaluation Means 18: Command distribution means 19: Execution result list 20: Standard execution time calculation means 21: Command execution means 22: Command processing program 31: Command name 32: Standard execution time 33: Start time 34: End time 35: Execution result 36 : Flags 41 to 47: Entry 51: Destination information 52: Operation attribute 53: Standard execution time 54: Result return method information 55: Command text

Claims (8)

A first node for delivering commands;
A second node that receives and executes the command;
The first node detects the load of the second node without the second node performing an operation of measuring its own load;
A computer system, wherein the first node is configured to control delivery of the command to the second node in accordance with the detected load. The computer system according to claim 1,
The first node is configured to calculate a command execution time actually required to execute the command in the past in the second node and detect a load of the second node based on the command execution time. Computer system. A computer system according to claim 2,
The second node is configured to return an execution result to the first node after receiving and executing the command;
The computer system, wherein the first node calculates the command execution time from a time when the execution result is received from the second node. A computer system according to claim 2,
The second node is configured to return an execution result to the first node after receiving and executing the command;
In the execution result, a return time at which the second node returns the execution result to the first node is described.
The computer system, wherein the first node calculates the command execution time from a previous return time described in the execution result. A computer system according to any one of claims 2 to 4,
The computer system is configured to detect a load of the second node based on an excess time that is a portion of the command execution time that exceeds a predetermined standard time. A computer system according to any one of claims 1 to 4,
Each of the commands has an operation attribute set,
Based on the operation attribute of each of the commands, the first node waits for transmission of the command according to the load of the second node, and cancels the operation of the command according to the load of the second node A computer system configured to selectively perform an operation and an operation of sending the command to the second node regardless of the detected load of the second node. A delivery means for delivering a command to a command delivery destination node;
Load detecting means for detecting the load of the command delivery destination node,
The delivery means is configured to control delivery of the command to the second node according to the detected load,
The load detection means is a computer that detects the load of the command distribution destination node without using a result of the command distribution destination node measuring its own load. The computer according to claim 7,
The load detection means calculates a command execution time actually required to execute the command in the command distribution destination node in the past, and detects the load of the second node based on the command execution time. Configured computer system.

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