JP5446666B2 - Process management program and process management method - Google Patents

Description

  The present invention relates to a technique for managing a process.

  In an operating system such as UNIX (registered trademark), when a child process that is an execution subject of an application terminates abnormally for some reason, the parent process restarts the child process so that the operation of the application is continued. It has been. Also, when the parent process terminates before the child process, the resources used by the child process cannot be released, so a system process called "init process" is set as the child process's foster parent. .

Japanese Patent Laid-Open No. 01-224846

  However, since the system process does not correspond to a specific application, when a child process having the system process as a foster parent terminates abnormally, the child process cannot be restarted. For this reason, if a child process whose foster parent is a system process is abnormally terminated, there is a possibility that the operation of the application cannot be continued.

  Therefore, in view of the problems of the prior art, a process management technology that can continue application operation even if the child process terminates abnormally after the parent process terminates abnormally by adopting the proxy parent process corresponding to the application as the foster parent The purpose is to provide.

  For this reason, in the proposed technique, when the computer that manages the process based on the control table on the memory that defines the parent-child relationship between the parent process and the child process detects the abnormal termination of the parent process, the proxy parent process The parent-child relationship of the control table is updated so that it becomes the parent process. Here, the surrogate parent process refers to a process that becomes a foster parent acting on behalf of monitoring and management of a child process by the parent process.

  According to the proposed technique, when the parent process terminates abnormally, the proxy parent process monitors and manages the child process, so that the child process terminated abnormally can be restarted. For this reason, even if the child process is abnormally terminated, the operation of the application can be continued, and a highly reliable information system can be constructed.

It is explanatory drawing of the process parent-child relationship in an initial state. It is explanatory drawing of the process parent-child relationship after a parent process abnormal end. It is a block diagram of the various functions which a computer embodies. It is explanatory drawing of a control table. It is explanatory drawing of the parent-child relationship between a parent process and a child process. It is a flowchart which shows a process end detection process. It is a flowchart which shows a control table update process. It is explanatory drawing of the parent-child relationship updated when a parent process is abnormally terminated. It is explanatory drawing of the 1st modification of a proxy parent process. It is explanatory drawing of the 2nd modification of a proxy parent process. It is explanatory drawing of the precondition for considering a specific example. FIG. 11 is a sequence diagram when a parent process ends before a child process. FIG. 11 is a sequence diagram when a proxy parent process ends before a parent process.

Hereinafter, the proposed technique will be described in detail with reference to the accompanying drawings.
In an operating system such as UNIX (registered trademark), a program in an execution state is called a “process”, and a new process can be generated from an arbitrary process. In this case, a process that generates a new process is called a “parent process”, while a process generated from the parent process is called a “child process”.

In the proposed technique, as shown in FIG. 1, the proxy parent process that substitutes the parent process PP is set to one of the child processes CP _{1 to} CP _{n + 1} . When the parent process PP abnormally terminated, as shown in FIG. 2, by a foster child CP n _{+ 1} the child CP ₁ ~ CP _n as a surrogate parent process, there are orphan process So that the application can continue to operate.

  Specifically, as illustrated in FIG. 3, the computer 10 functioning as a process management apparatus executes a process management program installed in the storage, thereby executing a process end detection unit 20, a control table update unit 30, Are each embodied. Here, the process management program is installed in an operating system and installed in a computer storage from a computer-readable recording medium such as a CD-ROM. The process end detection unit 20 and the control table update unit 30 are examples of a process end detection unit and a control table update unit, respectively.

  In the application having one parent process and a plurality of child processes, the process end detection unit 20 detects that the parent process has ended abnormally due to, for example, a hardware failure or a software failure. The control table update unit 30 updates the control table 40 expanded in the memory when the process end detection unit 20 detects the abnormal end of the parent process.

  The control table 40 defines the relationship between the parent process and the child process (parent-child relationship) in order to manage the process, and is independent for each process, that is, for each parent process and each child process. Provided. As shown in FIG. 4, the control table 40 has a pointer to a child process, a pointer to a sibling process (another child process generated by the same parent process), a pointer to the parent process, and a pointer to the proxy parent process. . Here, as will be described later, the “proxy parent process” is an alternative that, when the parent process ends abnormally for some reason, monitors the end of the child process, releases resources, collects charging information, etc., instead of the parent process. Is a process. In the control table 40, when a pointer to a child process, sibling process, parent process, or proxy parent process is not set, that is, when there is no relationship with another process, for example, there is nothing. “NULL” or the like indicating this is set.

Here, how the relationship between the parent process and the child process by the control table 40 is performed will be described using specific examples. As a precondition, as shown in FIG. 5, in an application in which the child processes CP _{1 to} CP ₃ are sequentially generated by the parent process PP, it is assumed that the child process CP ₃ functions as a proxy parent process.

When the parent process PP creates the child process CP ₁ , the operating system sets a pointer to the child process CP ₁ in the child process of the control table 40 of the parent process PP and the parent process of the control table 40 of the child process CP _1. Is set to a pointer to the parent process PP. When the parent process PP creates the child process CP ₂ , the operating system sets a pointer to the child process CP _{2 in} the sibling process of the control table 40 of the child process CP ₁ and also controls the control table 40 of the child process CP _2. A pointer to the parent process PP is set in the parent process. Further, when the parent process PP creates the child process CP ₃ , the operating system sets a pointer to the child process CP _{3 in} the sibling process of the control table 40 of the child process CP ₂ , and the control table 40 of the child process CP _3. A pointer to the parent process PP is set in the parent process. By calling "surrogate parent process setup procedure" when generating the parent process PP child process CP _3, pointers to child CP ₃ surrogate parent process control table 40 of the parent process PP is set. Then, the child process CP ₁ specified by the child process of the control table 40 of the parent process PP, by tracing the sibling process of the control table 40 sequentially child CP ₁ ~ CP ₃ that are related to the parent process PP Can be specified.

The process in which the parent process PP calls the “proxy parent process setting procedure” is an example of a proxy parent registration unit.
FIG. 6 shows a process end detection process that the process end detection unit 20 repeatedly executes at predetermined time intervals when the execution of the process management program is started.

  In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), the process end detection unit 20 determines whether or not the parent process has ended abnormally. Then, the process end detection unit 20 advances the process to Step 2 if it is determined that the parent process has ended abnormally (Yes), and ends the process if it determines that the parent process has not ended abnormally (No). .

In step 2, the process end detection unit 20 transmits a process abnormal end notification indicating that the parent process has ended abnormally to the control table update unit 30.
FIG. 7 shows a control table update process that is executed when the control table update unit 30 receives a process abnormal end notification from the process end detection unit 20.

  In step 11, the control table update unit 30 refers to the control table 40 of the parent process and determines whether or not a child process exists through whether or not a pointer is set for the child process. If the control table update unit 30 determines that the child process exists, the control table update unit 30 proceeds to step 12 (Yes), but determines that the child process does not exist (only the parent process exists). If not, the process is terminated (No).

  In step 12, the control table update unit 30 refers to the control table 40 of the parent process, and determines whether or not the proxy parent process has been registered through whether or not a pointer is set for the proxy parent process. judge. Then, if the control table update unit 30 determines that the proxy parent process has been registered, the process proceeds to step 13 (Yes), while if it determines that the proxy parent process has not been registered (not registered). The process proceeds to step 14 (No).

  In step 13, the control table update unit 30 selects the proxy parent process registered in the parent process control table 40 as a new parent process, and then advances the process to step 15.

In step 14, after the control table update unit 30 selects the system process as a new parent process, the process proceeds to step 15.
In step 15, the control table update unit 30 refers to the control table 40 of the parent process, and selects the first child process related to the parent process.

  In step 16, the control table update unit 30 determines whether the child process is a new parent process through whether the pointer of the new parent process points to the selected child process. If the control table update unit 30 determines that the child process is not a new parent process, the process proceeds to step 17 (Yes), while if the child process is determined to be a new parent process, the process proceeds to step 18. Proceed to No (No).

  In step 17, the control table update unit 30 sets a new parent process in the parent process of the control table 40 for the selected child process, and then proceeds to step 19.

  In step 18, the control table update unit 30 sets a system process for the selected child process (proxy parent process) in the parent process of the control table, and then advances the process to step 19.

  In step 19, the control table update unit 30 refers to the control table 40 of the selected child process, and determines whether there is a sibling process through whether a pointer is set for the sibling process. If the control table update unit 30 determines that there is no sibling process (has processed up to the last child process), the control table updating unit 30 terminates the processing (Yes), while if it determines that there is a sibling process, the process proceeds to step 20. (No).

  In step 20, the control table update unit 30 selects the sibling process set in the control table 40 of the selected child process as a child process, and then returns the process to step 16.

Here, for the purpose of facilitating the understanding of the process management technique, how the relationship between the parent process and the child process shown in FIG. 5 changes will be described.
When the process end detection unit 20 detects the abnormal end of the parent process PP, the child process in the control table 40 of the parent process PP is referred to and it is determined whether or not the child process exists. Since the child process CP ₁ is related to the control table 40 of the parent process PP, it is determined that there is a child process. Further, the proxy parent process in the control table 40 of the parent process PP is referred to, and it is determined whether or not the proxy parent process has been registered. Since the child process CP ₃ is set as the proxy parent process in the control table 40 of the parent process PP, it is determined that the proxy parent process is registered. Then, a child process CP _{3 that} is a proxy parent process is selected as a new parent process.

Further, it is determined whether or not the child processes CP _{1 to} CP ₃ sequentially traced from the parent process PP are new parent processes. Since the child processes CP ₁ and CP ₂ are not new parent processes, the child process CP ₃ is set in the parent process of the control table 40. On the other hand, since the child process CP ₃ is a new parent process, the system process SP is set as the parent process of the control table 40.

Through this process, the control table 40 of the child processes CP _{1 to} CP ₃ is updated as shown in FIG. In this case, the child process CP ₃ as the proxy parent process monitors the end of the child processes CP ₁ and CP ₂ and the system process SP as the parent process prepares for the abnormal end of the child process CP _3. Is set.

  For this reason, when the parent process is abnormally terminated, the proxy parent process can perform child process termination monitoring, resource release, charging information collection, and the like. Further, since the proxy parent process is generated from the parent process, the proxy parent process corresponds to the application, and the abnormally terminated child process can be restarted.

  Therefore, even if the child process is abnormally terminated, the operation of the application can be continued, and a highly reliable information system can be constructed. At this time, if a proxy parent process different from the parent process terminates abnormally, the system process is set as the parent process, so that the resource used by the proxy parent process is not released, etc. Can do.

  Since the surrogate parent process is registered as a child process of the parent process, when the surrogate parent process ends abnormally, the surrogate parent process is restarted by the parent process in the same manner as other child processes.

When the parent process PP is abnormally terminated, the parent process PP restarted by the system process SP may be used as the proxy parent process of the proxy parent process, as shown in FIG. Further, when the parent process PP ends abnormally, a mechanism for notifying the proxy parent process that the parent process PP has ended abnormally is incorporated as a proxy parent process of the proxy parent process, as shown in FIG. The process AP generated by the proxy parent process that has received the request may be used.

Next, as shown in FIG. 11, a specific case processed by the operating system will be considered on the premise of an application in which the child processes CP _{1 to} CP ₃ are associated with the parent process PP. In addition, it is assumed that a child process CP ₃ to function as a surrogate parent process.

(A) When the parent process PP ends before the child processes CP _{1 to} CP ₃ (FIG. 12)
When the application is activated, the parent process PP sequentially generates child processes CP _{1 to} CP ₃ . The child processes CP ₁ and CP ₂ start executing the application. Next, the parent process PP sets the child process CP ₃ as its proxy parent process. Thereafter, the parent process PP starts monitoring the child processes CP _{1 to} CP ₃ . When the parent process PP ends abnormally, the system process SP detects the abnormal end of the parent process PP and restarts the parent process PP.

On the other hand, when the parent process PP is abnormally terminated, the child process CP ₃ that is the proxy parent process is set in the parent process of the control table 40 of the child processes CP ₁ and CP ₂ by the above-described mechanism. Then, the child process CP ₃ that is the proxy parent process starts monitoring the child processes CP ₁ and CP ₂ when the parent process PP ends.

The parent process PP restarted by the system process SP notifies the child process CP ₃ that is the proxy parent process that the restart has been performed. Receiving this notification, the child process CP ₃ sets the restarted parent process PP as its proxy parent process.

Then, when the child process CP ₁ is completed, the process end notice by software interrupt is sent to the child process CP _3, the child process CP _3, performs such resource release and traffic collection of child CP _1.

(B) When the child process CP ₃ ends before the parent process PP (FIG. 13)
When the application is activated, the parent process PP sequentially generates child processes CP _{1 to} CP ₃ . The child processes CP ₁ and CP ₂ start executing the application. Next, the parent process PP sets the child process CP ₃ as its proxy parent process. Thereafter, the parent process PP starts monitoring the child processes CP _{1 to} CP ₃ .

When the child process CP ₃ is a surrogate parent process terminates abnormally, the process end notice by software interrupt is sent to the parent process PP. Parent process PP, which has received the process end notification, surrogate parent Given that the process is no longer, to create a child process CP ₃ is a surrogate parent process in the software interrupt handler again, set again to surrogate parent process.

The control table 40 only needs to be able to define the parent-child relationship between the parent process PP and the child process CP without adopting the data structure described above.
Regarding the above embodiment, the following additional notes are disclosed.

  (Supplementary Note 1) In a process management program for managing a process based on a control table on a memory that defines a parent-child relationship between a parent process and a child process, a proxy parent registration means for registering a computer as a proxy parent process of the parent process, A process end detecting unit for detecting an abnormal end of the parent process; and when the abnormal end of the parent process is detected by the process end detecting unit, the surrogate parent process becomes a parent process of the child process. A process management program that functions as a control table update unit that updates a parent-child relationship.

  (Supplementary note 2) The process management program according to supplementary note 1, wherein the proxy parent process is registered as one of the child processes in the control table.

  (Supplementary Note 3) When the parent-child relationship of the control table is updated, the control table update unit registers the parent process restarted by the system process as the proxy parent process of the proxy parent process functioning as the parent process. The process management program according to appendix 1 or appendix 2 characterized by the above.

  (Supplementary Note 4) When the parent-child relationship of the control table is updated, the control table update unit registers the proxy process generated by the proxy parent process as the proxy parent process of the proxy parent process that functions as the parent process. The process management program according to supplementary note 1 or supplementary note 2, wherein

  (Supplementary Note 5) In any one of Supplementary Note 1 to Supplementary Note 4, wherein the control table update unit selects a system process as a proxy parent process when no proxy parent process is registered in the control table. The process management program described.

  (Supplementary note 6) In a process management method for managing a process based on a control table on a memory that defines a parent-child relationship between a parent process and a child process, a computer registers a proxy parent process of the parent process and the parent process A process management method comprising: updating a parent-child relationship of the control table so that the proxy parent process becomes a parent process of a child process when an abnormal end of the process is detected.

  (Supplementary note 7) In a computer-readable recording medium recording a process management program for managing a process based on a control table on a memory that defines a parent-child relationship between a parent process and a child process, the computer is replaced with a proxy parent of the parent process. Proxy parent registration means for registering a process, process end detection means for detecting abnormal termination of the parent process, and when the parent process is detected abnormally by the process end detection means, the proxy parent process is a parent process of a child process. A computer-readable recording medium having a process management program recorded thereon, which functions as control table updating means for updating a parent-child relationship of the control table.

10 Computer 20 Process End Detection Unit 30 Control Table Update Unit 40 Control Table PP Parent Process CP Child Process AP Proxy Process

Claims (4)

In a process management program for managing a process based on a control table on a memory that defines a parent-child relationship between a parent process and a child process,
Computer
Proxy parent registration means for registering the proxy parent process of the parent process in the control table as one of the child processes;
Process end detection means for detecting abnormal end of the parent process;
Control table updating means for updating a parent-child relationship of the control table so that the proxy parent process becomes a parent process of a child process when an abnormal end of the parent process is detected by the process end detection means;
Process management program characterized by functioning as The control table update unit registers a parent process restarted by a system process as a proxy parent process of a proxy parent process functioning as the parent process when updating the parent-child relationship of the control table. The process management program according to claim 1. The control table update unit registers a process generated by the proxy parent process as a proxy parent process of the proxy parent process functioning as the parent process when updating the parent-child relationship of the control table. The process management program according to claim 1 . In a process management method for managing processes based on a control table on a memory that defines a parent-child relationship between a parent process and a child process,
Computer
Registering the parent process of the parent process as one of the child processes in the control table;
Updating the parent-child relationship of the control table so that the proxy parent process becomes a parent process of a child process when an abnormal termination of the parent process is detected
Process management method characterized by