JP2009187171A - Checkpoint restart device and checkpoint restart method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use process identifiers effectively and restart processes reliably by virtualizing process identifiers. <P>SOLUTION: In a system of performing checkpoint/restart during process execution, a checkpoint file generation part 2, when receiving a checkpoint request, generates a checkpoint file 3 holding an interruption-based process identifier and information keeping a process 10 restartable, a restarting part 4, when receiving a restart request, restarts a restart process 20 according to the checkpoint file 3 and generates a process identifier conversion table 5 associating a restart-based process identifier with the interruption-based process identifier, and a process identifier conversion part 6 converts the process identifier according to the process identifier conversion table 5 when the restarted process processes a system call. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to process identifier assurance in computer systems. In particular, the present invention relates to the guarantee of a process identifier that is a restart target in an environment that provides a checkpoint / restart function.

  As basic software having a checkpoint / restart function, Patent Document 1 discloses a method of reserving a process identifier when collecting checkpoints. In this technique, when restarting from a checkpoint file, the process identifier is reserved so that other processes cannot be used so that the same process identifier as that at the time of checkpoint collection is assigned.

  However, it was not automatically known when the process identifier reserved at the time of checkpoint collection became unnecessary. For this reason, it is necessary to explicitly release process identifiers that are no longer needed by the administrator or user. In addition, a limit value for the number of checkpoints is provided so that process identifiers that are reserved at the same time are not exhausted. For this reason, it was necessary to release the reservation of the process identifier when the reserved process identifier was not used so that the checkpoint exceeding the limit value could not be collected or the number of checkpoints did not reach the limit value. .

  As described above, since the process identifier is guaranteed by reserving the process identifier, there is a problem that the process identifier cannot be effectively used. In addition, there is a problem that an open operation is required in operation.

In another method, if the process identifier is being used by another process at the time of restart, the restart fails, so the restart from the checkpoint file cannot be performed reliably.
JP-A-6-230981

  The present invention has been made in view of such circumstances, and an object of the present invention is to virtualize a process identifier and to effectively restart the process by effectively using the process identifier.

  One aspect of the checkpoint / restart apparatus according to the present invention generates a process to be assigned to a central processing unit, accepts a checkpoint request during execution of the process, interrupts processing of the process, and issues a restart request. Upon receipt, a checkpoint / restart device for resuming the processing of the process, a check for retaining a process identifier at the time of interruption assigned to the process and information for holding the process in a resumable state A point file, a checkpoint file generation unit for generating the checkpoint file when the checkpoint request is received, a process identifier at the time of restart assigned when the process is restarted, and a process identifier at the time of suspension Process identifier conversion to associate And when the restart request is received, the process is restarted based on the checkpoint file and the process identifier conversion table is generated, and the restarted process processes the system call. A process identifier conversion unit that converts the process identifier at the time of suspension and the process identifier at the time of restart based on the process identifier conversion table.

  According to another aspect of the checkpoint / restart method of the present invention, a process to be assigned to a central processing unit is generated, a checkpoint request is accepted during the process execution, the process of the process is interrupted, and a restart is performed. A checkpoint / restart method for resuming processing of a process upon receipt of a request, wherein the process identifier at the time of interruption assigned to the process and the process is resumed when the checkpoint request is accepted. A checkpoint file that holds information to be held in a possible state, and when the restart request is accepted, the process is restarted based on the checkpoint file and assigned when the process is restarted Process identifier at the time of restart and the process at the time of the interruption When a resumed process processes a system call, the process identifier at the time of suspension and the process identifier at the time of restart are converted based on the process identifier conversion table. To do.

  According to the present invention, by virtualizing the process identifier, it is possible to ensure the restart of the process by effectively using the process identifier.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals, and description thereof is omitted.

  In large-scale scientific and technical calculations, the program may run for several days or weeks. In the execution of such a program, if a failure of a computer or the like occurs in the middle of execution, the execution up to that point becomes useless, and the execution of the program must be started from the beginning. To solve this problem, a checkpoint function that saves the program state in a file and so on and a restart function that resumes program execution from this checkpoint are required so that program execution can be resumed. It becomes.

  In implementation of such a checkpoint / restart function, if the process identifier at the time of checkpoint collection and the process identifier after restart are not the same, the operation of the process after restart may not be guaranteed.

  According to a preferred embodiment of the present invention, in a computer system having a checkpoint / restart function, when a process is restarted, the process identifier is set so that the same process identifier as that at the time of checkpoint is assigned. By performing virtualization, checkpoint / restart can be reliably performed without limiting the number of checkpoints. Details will be described below.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration example of a checkpoint / restart apparatus according to Embodiment 1 of the present invention. The checkpoint / restart device generates a process to be assigned to a central processing unit (CPU), receives a checkpoint request during the process execution, interrupts the process of the process, and receives a restart request. A function of resuming processing of the process; Referring to FIG. 1, the checkpoint / restart apparatus of this embodiment includes a process generation unit 1, a checkpoint file generation unit 2, a checkpoint file 3, a restart processing unit 4, a process identifier conversion table 5, and a process identifier conversion. A unit 6 and a system call processing unit 7.

  The process generation unit 1 generates a process to be assigned to a central processing unit. FIG. 1 shows a state where the process generation unit 1 has generated the process 10. The process 10 is a target for checkpoint / restart.

  When receiving a checkpoint request, the checkpoint file generating unit 2 collects checkpoints and generates a checkpoint file 3. Specifically, the checkpoint file generation unit freezes the state of the process 10 to a state where it can be executed again, and includes information necessary for resumption including the process identifier at the time of interruption assigned to the process 10 in the checkpoint file. 3 is stored. When the process 10 is interrupted, the process identifier assigned to the process 10 (process identifier at the time of interruption) is released and can be assigned to another process.

  The checkpoint file 3 is a storage area that holds a process identifier at the time of interruption and information for holding the process in a resumable state. FIG. 2 shows a configuration example of the checkpoint file 3. Although FIG. 2 shows an example of a file having areas that can store a plurality of processes, one file may be generated for each process.

  When the restart processing unit 4 receives a restart request, the restart processing unit 4 generates a restart process 20 based on the checkpoint file 3, and restarts the interrupted process 10 as the restart process 20, and process identifier conversion And a function for generating the table 5. In addition to the process identifier at the time of interruption, a new process identifier at the time of restart is assigned to the restart process 20. In the internal process of the restart process 20, the restart processing unit 4 restarts the process so that the process is executed using the process identifier at the time of interruption. Further, the process identifier at the time of interruption and the process identifier at the time of restart are associated with each other and stored in the process identifier conversion table 5.

  The process identifier conversion table 5 is a storage area that associates the process identifier at the time of restart with the process identifier at the time of interruption. FIG. 3 shows a configuration example of the process identifier conversion table 5. Although FIG. 3 shows an example of a table having areas that can be stored for a plurality of processes, one table may be generated for each process.

  When the restarted restart process 20 processes a system call, the process identifier conversion unit 6 converts the process identifier at the time of interruption and the process identifier at the time of restart based on the process identifier conversion table 5. In other words, the process identifier conversion unit 6 virtualizes the process identifier in the system call request from the restart process 20. Specifically, the process identifier conversion unit 6 uses the process identifier for the argument or return value when the restart process 20 issues a system call request or returns the return value of the system call request. If the process identifier is used, the process identifier conversion table 5 is referenced to return the process identifier.

  The system call processing unit 7 has a function of performing processing requested by a system call request and returning a result. In this embodiment, the system call is not called directly from the restart process 20 but is called via the process identifier conversion unit 6, and the return value is also returned to the restart process 20 via the process identifier conversion unit 6. Will be. In the checkpoint / restart apparatus, the system call may be called through the process identifier conversion unit 6 in all processes including the process 10. The process identifier conversion unit 6 can determine whether or not the process identifier needs to be converted by referring to the process identifier conversion table and checking each time whether or not the process is a registered process.

  The outline of the operation of the checkpoint / restart apparatus shown in FIG. 1 is as follows. In the process 10, a checkpoint file 3 is generated by the checkpoint file generator 2. At this time, the process identifier information is also stored in the checkpoint file 3 at the same time. When the restart processing unit 4 performs a restart process using the checkpoint file 3, the process identifier stored in the checkpoint file 3 and the information of the process identifier newly assigned at the restart are also stored. The process identifier conversion table 5 is created in advance. When the restart processing unit 4 issues a system call while the restarted restart process 20 is executing a program, the process identifier conversion unit 6 determines whether a process identifier is specified as an argument or a return value. To do. If a process identifier is used, the process identifier conversion table 5 is referred to when a request is issued to the system call processing unit 7 or a return value from the system call processing unit 7 is returned to the restart process 20. To virtualize the process identifier.

  Next, the operation of this embodiment will be described in detail with reference to FIGS. FIG. 4 is a flowchart showing an operation example of the checkpoint / restart apparatus of this embodiment. First, the process generation unit 1 generates a process 10 and starts executing the process 10 (S11). The process 10 is interrupted by a request from the user (checkpoint request) or the like (S12), and the checkpoint file generation unit 2 generates the checkpoint file 3 so that the execution of the program can be resumed later. (S13). At this time, if the process identifier of the process 10 is 100, the checkpoint file generation unit 2 also stores information that the process identifier is 100 in the checkpoint file 3 (see FIG. 2).

  When the user later requests to restart the execution of the process 10 (S14), the restart processing unit 4 accepts the restart request, and the process identifier (process at the time of interruption) The information of the identifier, here 100) is acquired. The process identifier at the time of interruption is registered in the process identifier conversion table 5 together with the information of the process identifier newly assigned to the restart process 20 at the time of restart (process identifier at the time of restart, here 200) (S15). The restart process 20 starts executing the process (S16).

  When the restart process 20 issues a system call (YES in S17), the process identifier conversion unit 6 checks whether there is a process identifier in the argument or return value of the system call, and if the process call is in the argument or return value If the identifier is included, the process identifier conversion table 5 is referred to convert the process identifier, and the system call processing unit 7 processes the system call (S18). For example, a case where the restart process 20 issues a getpid () system call for checking its own process identifier will be described. Since the system call does not include a process identifier as an argument, the process identifier conversion unit 6 passes the request to the system call processing unit 7 as it is. The system call processing unit 7 returns the process identifier 200 of the process to the process identifier conversion unit. The process identifier conversion unit 6 refers to the process identifier conversion table 5 and determines that the process identifier that is actually 200 needs to be converted to 100 at the time of checkpoint collection (when the checkpoint file is generated). It is converted so that 100 is returned to the start process. Until the process of the restart process 20 ends (YES in S19), the processes from step S16 to S19 are repeated.

(Other embodiments)
In the first embodiment, the case where the process identifier is virtualized when the process issues a system call has been described as an example. In addition to the system call, when referring to an external program, the process identifier is virtualized as in the first embodiment when the process identifier is used as an argument or return value.

  According to a preferred embodiment of the present invention, the following effects are obtained. As a first effect, a function for reserving process identifiers is not required, and therefore, it can be operated without worrying about exhaustion of process identifiers due to an increase in the number of reserved process identifiers. Further, there is no need for processing for releasing process identifiers periodically reserved by an administrator or the like. This is because the restart process can behave as if the same process identifier as that at the time of checkpoint collection is assigned without reserving the process identifier.

  As a second effect, it is possible to reliably perform checkpoint collection. This is because it is not necessary to reserve a process identifier, and thus it is not necessary to provide a limit value for the number of checkpoints.

  As a third effect, even when the process identifier reservation function is not provided, the same process identifier can be assigned without failure, so that the restart process can be performed efficiently. This is because any process identifier that can be used at the time of restart can be assigned regardless of the value of the process identifier at the time of checkpoint collection.

  In addition, this invention is not limited to embodiment shown above. Within the scope of the present invention, it is possible to change, add, or convert each element of the above-described embodiment to a content that can be easily considered by those skilled in the art.

It is a figure which shows the structural example of the checkpoint / restart apparatus of Embodiment 1 which concerns on this invention. It is a figure which shows the structural example of a checkpoint file. It is a figure which shows the structural example of a process identifier conversion table. 3 is a flowchart illustrating an operation example of the checkpoint / restart apparatus according to the first embodiment.

Explanation of symbols

1 Process Generator 2 Checkpoint File Generator 3 Checkpoint File 4 Restart Processor 5 Process Identifier Conversion Table 6 Process Identifier Converter 7 System Call Processor 7
10 Process 20 Restart process

Claims (4)

Create a process to be assigned to a central processing unit, accept a checkpoint request during the execution of the process, interrupt the process, and restart the process when a restart request is accepted A device,
A checkpoint file that holds a process identifier at the time of suspension assigned to the process, and information that holds the process in a resumable state;
A checkpoint file generator that generates the checkpoint file when the checkpoint request is received;
A process identifier conversion table that associates a process identifier at the time of resumption assigned when the process is resumed with a process identifier at the time of suspension;
When the restart request is accepted, based on the checkpoint file, the process is restarted, and a restart processing unit that generates the process identifier conversion table;
When the resumed process processes a system call, a checkpoint / restart comprising a process identifier conversion unit that converts the process identifier at the time of suspension and the process identifier at the time of restart based on the process identifier conversion table apparatus. The checkpoint file generation unit releases the process identifier at the time of the interruption,
The resumed process is newly assigned the resume process identifier,
2. The checkpoint / restart apparatus according to claim 1, wherein the restart processing unit restarts the internal process of the process to be restarted so that the process is executed using the process identifier at the time of the interruption.   The process identifier conversion unit receives the process identifier at the time of suspension from the resumed process as an argument of the system call, converts the received argument to the process identifier at the time of restart, and executes the process of the system call, 2. The process identifier at the time of resumption is received as a return value of the processing of the system call, the process identifier at the time of suspension is set in the received return value, and the process identifier is output to the resumed process. Checkpoint / restart device. Create a process to be assigned to a central processing unit, accept a checkpoint request during the execution of the process, interrupt the process, and restart the process when a restart request is accepted A method,
When receiving the checkpoint request, generate a checkpoint file that holds a process identifier at the time of interruption assigned to the process and information for holding the process in a resumable state,
When the restart request is accepted, the process is restarted based on the checkpoint file, and the process identifier at the time of restart assigned to the process when restarted is associated with the process identifier at the time of suspension. Generate a process identifier conversion table,
A checkpoint / restart method for converting a process identifier at the time of suspension and a process identifier at the time of restart based on the process identifier conversion table when the resumed process processes a system call.

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