JP2009199166A - Information processing device, control method and program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the occurrence of a lock residue due to the interruption of access to a resource. <P>SOLUTION: An information processing device has: a resource access closing flag 130 having a value showing information on whether access to a resource of a user AP process 200 being executed by a user program 400 is closed; signal capture processing 110 capturing a signal emitted when failure occurs in an optional user AP thread 300; a resource access closing setting means 111 setting a value of the resource access closing flag 130 to the value of the information showing that the access is closed when the signal capture processing 110 captures the signal; and a resource access closing decision means 121 deciding whether the access to the resource is closed by examining the value of the resource access closing flag 130 when a thread in a process during execution accesses the resource of the process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an information processing apparatus, a control method thereof, and a program, and more particularly to processing when a running thread is interrupted.

  In general, an execution control unit of a program having information related to an execution state, such as a program counter or a stack, is called a thread. An execution control unit having resources used in the entire program, such as program code and global data, is called a process. One process has one or a plurality of threads.

  When an OS (Operating System) detects a signal event that inevitably interrupts the execution of the corresponding thread, such as an illegal address reference, while a certain thread is executing a program, the OS normally has all threads under the process to which the corresponding thread belongs. Suspends execution and terminates the process. The same applies when the user requests the OS to stop the process.

  Here, in a computer system in which multiple threads can operate in parallel, when multiple threads access the same shared resource, there is a risk that consistency is not guaranteed in order to guarantee the consistency of shared resources. Usually, a lock corresponding to a shared resource is acquired so that a plurality of threads do not execute an area (critical section) at the same time. Typical lock functions provided by the OS include semaphores and Mutex Lock (Mutual exclusion lock).

  While the thread is executing the program normally, the lock is acquired immediately before the dangerous area, and the lock is released immediately after leaving the dangerous area. However, if a signal event is detected during which the thread itself or other thread belonging to the same process must be interrupted while the thread is executing the dangerous area, the execution of the thread is interrupted and the lock is released. It will remain without being. If such a lock remains, all threads that attempt to acquire the lock of the same shared resource will stop waiting for the lock acquisition, which may cause a fatal system failure.

As techniques related to the present invention, there are those described in Patent Documents 1 and 2.
Patent Document 1 discloses an invention relating to dynamic replacement of a shared subroutine (program). Patent Document 1 describes that the exchange request flag is set to ON so that the corresponding shared subroutine (program address) is not called during replacement of the shared subroutine. However, the present invention relates to a technique for providing an access prevention flag in order to prevent unauthorized access to resources that cannot be normally accessed, and is not intended to reduce lock residuals, and is not relevant to the present invention. .

Patent Document 2 discloses an invention related to termination synchronization processing in a case where all processes are terminated in accordance with an operation instruction or abnormal termination of some processes in a plurality of processes operating in conjunction with each other. The invention described in Patent Document 2 is characterized by managing the states of all related processes and newly providing a synchronization procedure when a specific management process stops all remaining processes. Patent Document 2 also describes a related process group control improvement.
Japanese Patent Laid-Open No. 04-039739 JP 04-241633 A

  In the conventional system, as a method of avoiding the system failure due to the above-mentioned lock remaining, when restarting the aborted process, an attempt is made to acquire locks for all locks that may have been locked at the time of the abort. If lock acquisition is not completed within a certain time, it is determined that the corresponding lock remains, and a mechanism that disables the shared resource corresponding to the corresponding lock or recreates the shared resource is used. However, in the case of this method, the time required for the lock inspection increases depending on the number of locks in which locks remain, and therefore it may take a long time to recover the system by restarting the process.

  In view of the above circumstances, an object of the present invention is to reduce the occurrence of lock residue due to interruption of resource access.

  In order to achieve the above object, the present invention has the following features.

  In the information processing apparatus according to the present invention, a failure has occurred in a resource access block flag having a value indicating whether or not access to a resource of a process being executed is blocked, and an arbitrary thread in the process A signal capture processing means for capturing a signal emitted in the case, and when the signal capture processing means captures a signal, the value of the resource access block flag is set to a value of information indicating that the access is blocked Whether the access to the resource is blocked by checking the value of the resource access block flag when the resource access block setting means and the thread in the process being executed access the resource of the process. Resource access blockage determining means for determining.

  A method for controlling an information processing apparatus according to the present invention is a method for controlling an information processing apparatus having a resource access block flag having a value indicating whether or not access to a resource of a process being executed is blocked. , A signal capture processing step for capturing a signal emitted when a failure occurs in an arbitrary thread in the process, and the value of the resource access block flag is accessed when the signal is captured by the signal capture processing step A resource access blockage setting step for setting a value of information indicating that the block is blocked, and by checking a value of the resource access blockage flag when a thread in an executing process accesses the process, And a resource access blockage determining step for determining whether or not access to the resource is blocked.

  A program according to the present invention causes an information processing apparatus having a resource access blocking flag having a value indicating whether or not access to a resource of a process being executed is blocked to a failure in an arbitrary thread in the process. A signal capturing process for capturing a signal that is generated when an error occurs, and when the signal is captured by the signal capturing process, the value of the resource access block flag is changed to an information value indicating that the access is blocked Whether or not access to the resource is blocked by checking the value of the resource access block flag when the resource access block setting process to be set and the thread in the executing process access the process And determining resource access blockage determination.

  According to the present invention, it is possible to reduce the occurrence of lock remaining due to resource access interruption.

First, an outline of the lock residual occurrence reduction method in the present embodiment will be described.
In a computer system in which multiple threads can operate in parallel, when multiple threads access the same shared resource, a critical area where consistency is not guaranteed (critical) to ensure the consistency of shared resources Usually, a lock corresponding to a shared resource is acquired so that a plurality of threads do not execute the section (section) at the same time.

  However, if the thread is interrupted while acquiring the lock for some reason, the lock remains without being released, and all threads that subsequently acquire the lock of the same shared resource Will stop waiting for lock acquisition. Here, as a case where the thread is interrupted, the following three patterns can be considered.

  The first case is that the OS (operating system) aborts due to a failure of the process itself that acquires the lock. Secondly, there is no problem with the process itself that has acquired the lock, and the previous thread in the form of a wrapping as the OS specification in accordance with the abortion caused by the malfunction of the process in another thread in the same process. The case where is cut off. Third, there is no problem with the process itself that acquires the lock, and the process is explicitly aborted by the will of the other thread (/ other process) program.

  Among the above, this embodiment is intended for the second case. According to the specification of the present embodiment, in addition to a thread that must be aborted due to a failure, another thread of the same process that does not have a failure is immediately aborted, so that the lock remains. In order to solve the above-described problem, the present embodiment detects that all threads in the process are forcibly terminated by the OS, and suppresses the occurrence of lock remaining due to the forced termination.

Next, the configuration of the information processing apparatus according to the present embodiment will be described with reference to the drawings.
As illustrated in FIG. 1, the information processing apparatus according to the present embodiment includes a resource access library 100 and is executing a user AP process 200. The user AP process 200 includes a plurality of user AP threads 300 that execute the user program 400.

  The resource access library 100 includes a resource access process 120 having a resource access blockage determining unit 121 and a resource access unit 122, a signal capturing process 110 having a resource access blockage setting unit 111 and a process abort delay unit 112, and a resource access blockage flag 130. Is provided. Further, the signal capturing process 110 is registered in advance in the OS while the information processing apparatus according to the present embodiment is activated.

  Here, the resource access block flag 130 is a storage area unique to each user AP process 200 and has an initial value of 0. When the value of the resource access block flag 130 is an initial value, the flag is OFF (in other words, the flag is not set). When the value is not the initial value, the flag is ON (in other words, the flag is set). ing). The value of the resource access block flag 130 indicates information indicating whether or not access to the resource of the user AP process 200 is blocked. In this embodiment, the access is not blocked in the case of the initial value. If it is not the initial value, it indicates information where access is blocked.

  Next, the operation of the lock residual occurrence reducing method in the present embodiment configured as described above will be described. FIG. 2 is a flowchart showing the flow of signal capture processing in the present embodiment.

  In FIG. 2, after the user AP process 200 including a plurality of user AP threads 300 for executing the user program 400 is started (step S201), the user program 400 operating on an arbitrary user AP thread 300 (step S202). When the OS detects a situation in which the execution of the thread must be interrupted, such as an illegal address reference (step S203), the signal capture processing 110 registered in the OS from the OS in advance by extension of the corresponding user AP thread 300 is executed. Called (step S204).

  In the signal capturing process 110, control is first passed to the resource access block setting unit 111. The resource access block setting unit 111 sets 1 to the resource access block flag 130 (step S205), and passes control to the process abort delay unit 112. Note that setting the resource access blockage flag 111 to 1 by the resource access blockage setting unit 111 may be rephrased as “turning on the resource access blockage flag 130 (or setting the flag)”.

  The process abort delay unit 112 waits for execution of a thread for a predetermined time (step S206), and then returns control to the OS (step S207). As a result, the OS interrupts execution of all user AP threads 300 included in the user AP process 200 and ends the user AP process 200.

  On the other hand, the resource access process in this embodiment is executed according to the flow shown in the flowchart of FIG. In FIG. 3, after the user AP process 200 including a plurality of user AP threads 300 for executing the user program 400 is activated (step S301), the user program 400 (step S302) operating on an arbitrary user AP thread 300 is started. Then, the resource access process 120 is called (step S303).

  In the resource access process 120, control is first transferred to the resource access blockage determination unit 121. The resource access blockage determination unit 121 determines the value of the resource access blockage flag 130 (step S304). If the value of the resource access block flag 130 is 0 (step S305 / Yes), control is passed to the resource access unit 122 (step S306). If the value of the resource access block flag 130 is other than 0 (No in step S305), it is determined that the resource access is impossible and the control is returned to the user program 400 (step S307).

  Next, the operation of the resource access unit 122 in this embodiment will be described with reference to the flowchart of FIG. In FIG. 4, the resource access unit 122 acquires the lock of the target resource (step S401), executes the requested access process (step S402 / Yes), and then releases the lock of the resource (step S403). ), Control is returned to the user program 400 (step S404).

  In the present embodiment, when a non-recoverable signal event occurs in a certain thread in the process (multi-thread process) composed of a plurality of threads, the signal capturing process registered in the OS in advance is performed. In the extension called from the process, the resource access block flag in the process is set to ON to suppress the execution of new resource access processing in the process and the resource access processing already being executed in other threads in the process. In order to wait for completion, by waiting for a certain time for the thread in which the signal event has occurred to be aborted (suspended), occurrence of residual lock due to interruption of resource access processing during lock acquisition is reduced.

  As a result, when restarting an aborted process, the time required for checking all locks that may have been locked at the time of the abort is shortened, and the time required for system recovery by process restart is shortened. .

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention. The control operation in the present embodiment described above can also be executed using hardware, software, or a combined configuration of both.

  In the case of executing processing using software, it is possible to install and execute a program in which a processing sequence is recorded in a memory in a computer incorporated in dedicated hardware. Alternatively, the program can be installed and executed on a general-purpose computer capable of executing various processes.

  For example, the program can be recorded in advance on a hard disk or ROM (Read Only Memory) as a recording medium. Alternatively, the program can be stored (recorded) temporarily or permanently in a removable recording medium. Such a removable recording medium can be provided as so-called package software. The removable recording medium includes a floppy (registered trademark) disk, a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto optical) disk, a DVD (Digital Versatile Disc), a magnetic disk, a semiconductor memory, and the like.

  The program is installed in the computer from the removable recording medium as described above. In addition, it is wirelessly transferred from the download site to the computer. In addition, it is transferred to the computer via a network by wire.

It is a block diagram which shows the structure of embodiment of this invention. It is a flowchart which shows the signal capture process of this embodiment. It is a flowchart which shows the resource access process of this embodiment. It is a flowchart which shows operation | movement of the resource access means of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Resource access library 110 Signal capture process 111 Resource access blockage setting means 112 Process abort delay means 120 Resource access process 121 Resource access blockage determination means 122 Resource access means 130 Resource access block flag 200 User AP process 300 User AP thread 400 User program

Claims (6)

A resource access blocking flag comprising a value indicating whether or not access to the resource of the process being executed is blocked;
Signal capturing processing means for capturing a signal emitted when a failure occurs in any thread in the process;
Resource access blockage setting means for setting the value of the resource access blockage flag to the value of information indicating that the access is blocked when the signal capture processing unit captures a signal;
Resource access blockage determining means for determining whether access to the resource is blocked by checking the value of the resource access blockage flag when a thread in the executing process accesses the resource of the process When,
An information processing apparatus comprising:   Process abort delay means for waiting for a predetermined time for the operating system of the information processing apparatus to execute the abort of the process when it is determined by the resource access blocking determination means that access to the resource is blocked The information processing apparatus according to claim 1, further comprising: A control method for an information processing apparatus having a resource access block flag having a value indicating whether or not access to a resource of a process being executed is blocked,
A signal capturing process for capturing a signal emitted when a failure occurs in any thread in the process;
A resource access blockage setting step for setting the value of the resource access blockage flag to a value of information indicating that the access is blocked when a signal is captured by the signal capture processing step;
A resource access blockage determining step for determining whether or not access to the resource is blocked by checking the value of the resource access blockage flag when a thread in the process being executed accesses the process;
A method for controlling an information processing apparatus, comprising:   A process abort delay step of waiting for a predetermined time for the operating system of the information processing apparatus to execute the abort of the process when the resource access blocking determination unit determines that the access to the resource is blocked; The information processing apparatus control method according to claim 3, further comprising: In an information processing apparatus having a resource access block flag having a value indicating whether access to resources of a process being executed is blocked or not,
A signal capturing process for capturing a signal emitted when a failure occurs in any thread in the process;
A resource access blockage setting process for setting a value of the resource access blockage flag to a value of information indicating that the access is blocked when a signal is captured by the signal capture process;
A resource access blockage determination process for determining whether or not access to the resource is blocked by examining the value of the resource access blockage flag when a thread in the process being executed accesses the process;
A program characterized by having executed. In the information processing apparatus,
A process abort delay process that waits a predetermined time for the operating system of the information processing apparatus to execute the abort of the process when it is determined by the resource access blocking determination process that the access to the resource is blocked 6. The program according to claim 5, further comprising:

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