JPH05189253A - Exclusive control method for common resource in computer - Google Patents

Abstract

PURPOSE:To prevent the time-out of an online terminal even if traffic is con gested, to occupy resource preferentially and to automatically release a deadlock being a serious fault as an online system. CONSTITUTION:(1) When the number of designated registration queuing is larger than that which is previously registered for prescribed resource at the time of declaring prescribed resource (step S2), occupation impossible information on the resource is returned to an application (step S3). (2) Priority is provided for same resource, and FIFO control is executed at every level (steps S12-S14). (3) Queuing time is supervised (step S21). When it exceeds prescribed time, (step S22), the effect is returned to the application (step S23), and the deadlock is released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exclusive control method for common resources in a computer.

[0002]

2. Description of the Related Art In an online system as shown in FIG. 7, all online terminals T # 1 to T # i can perform the same business. Exclusive control in this type of online system is conventionally performed by the method shown in FIG. That is, since task A, task B, and task C each use a common resource of the computer, the occupation of resource R is declared. FIG. 8 shows an example in which declarations are made in the order of task A → task B → task C.

In this case, the other tasks B and C are kept waiting until the task A declares the release of the resource R. During the declaration of occupation of the resource R, the TCB (task control block) addresses of the tasks A, B, and C are registered in the management queue of the resource R.

FIG. 9 shows a conceptual diagram when the resource R is registered in the management queue. That is, the fact that the task A, the task B, and the task C are queued in the resource R means that the TCB address (a) of the task A is registered in the resource R management block, and the TCB address of the task B (b) is registered in the TCB of the task A. ) Is registered, and 0 is registered in the TCB of task C in the final meaning.

[0005]

However, in the above-described conventional exclusive control method, when, for example, 10 tasks are registered in the management queue of the resource R, the 10th task queued is 1 to 9 tasks. Since the waiting is done until all the tasks are processed, the response is delayed when the transaction amount is congested, and the online terminal times out. Furthermore, since the processes are processed in the order in which they are registered in the management queue, it was not possible to preferentially occupy the resources and shorten the waiting time.

When a task occupies a plurality of resources by exclusive control, deadlock occurs between tasks,
There was also a problem that subsequent processing could not be performed. That is, in FIG. 10, task A declares occupation in the order of resource Ra → resource Rb, task B declares occupation in the order of resource Rb → resource Ra, and task A declares occupation of resource Rb. At this time, with respect to the resource Rb, the task B has already declared occupancy, and therefore, it is a wait. On the other hand, when the task B declares the occupation of the resource Ra, the task A already occupies the resource Ra, so that the waiting is made. Therefore, both tasks A and B are in a waiting state, and are in a deadlock state.

Therefore, according to the present invention, it is possible to prevent the time-out of the online terminal even when the traffic is congested, preferentially occupy the resource, and automatically cancel the deadlock which is a serious obstacle as the online system. The purpose is to provide an exclusive control method for common resources.

[0008]

According to the method for exclusive control of a common resource according to the present invention, when declaring occupancy of a predetermined resource, the number of waiting for registration is designated, and the designated number is preset for the predetermined resource. If it is larger than the registered number,
The non-occupancy information of the predetermined resource is returned to the application.

[0009] Further, when a priority is set for the same resource and a occupancy of a predetermined resource is declared, a priority level is designated,
When the designated priority level has a higher priority than the designated priority level, the resource is preferentially occupied. Furthermore, when a waiting state occurs due to the occurrence of a deadlock state, the waiting time is monitored, and when this waiting time exceeds a specified time, the fact is returned to the application and the deadlock is released. To

[0010]

When the occupancy of the predetermined resource is declared, if the designated number of registration waits is larger than the number registered in advance for the predetermined resource, the resource occupancy information is returned to the application. By doing so, delay in response can be prevented even if traffic is congested, and thus timeout of online terminal can be prevented.

Further, by assigning priority to the same resource and performing FI (First-in) FO (First-out) control for each level, the resource can be preferentially occupied, so that a priority terminal / general terminal Can be controlled. Furthermore, monitor the waiting time,
When the specified time is exceeded, the fact is returned to the application and the deadlock, which is a serious failure as an online system, is automatically released.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. The exclusive control method for common resources according to the present invention is
It has a resource occupancy registration processing function, a resource occupancy cancellation processing function, and a resource occupancy time monitoring processing function, and the respective processing flows are shown in FIGS. 1 (A), 1 (B) and 1 (C). First, as shown in FIG. 2, the resource occupancy registration processing function is a function of designating the number of waiting for registration by the application (AP) when, for example, the task D declares occupancy of the resource R.

That is, in FIG. 1A, first, it is judged whether or not the number of registered items is designated (step S1),
If there is a designation, it is determined whether or not the designated number of registration waits exceeds the registered number (step S2). If the registered number is exceeded, the resource R cannot be occupied is returned to the AP (step S3). If the registered number is not specified or the registered number is not exceeded, the task D is registered in the management queue of level i ( Step S4).

For example, when the number of waiting for registration is designated as "4", if three resources have already been registered for the resource R, the resource R cannot be occupied by the AP and immediately A
Return to P. Therefore, the AP can notify the user of the message indicating the congestion. On the other hand, in the past, since the resource R was unconditionally registered when it was occupied, the task registered at the end of the resource R is waited until all processing is completed, and the response to the user is delayed. It was

Next, the resource occupation release processing function is a function of designating a priority level when the task K declares occupation of the resource R, as shown in FIG. For example, after task A, task B, and task C make a declaration to occupy the resource R at level 2, task K makes a declaration to occupy the same resource R at level 1. Note that level 1 has a higher priority than level 2. The order of processing at this time is
Task A → task K → task B → task C. On the other hand, conventionally, processing was performed in the order of task A → task B → task C → task K.

That is, in FIG. 1B, the task of level i (level 2) is first unregistered by releasing the resource R (step S11), and then the resource R of the priority level (level 1) is waited for. It is determined whether or not there is a task (step S12). If there is a resource waiting task at the priority level, the task waiting at the priority level can be occupied and returned to the AP (step S13). If there is no resource waiting task at the priority level, wait at level i Task can be occupied and returned to AP (step S1)
4).

Next, the resource occupation time monitoring processing function, for example, when the tasks A and B occupy the resources Ra and Rb,
As shown in FIG. 4, even if a deadlock occurs between tasks, it is a function that automatically releases the deadlock state after a certain period of time. For example, for task B, task A has resource Ra
It is assumed that the task A is in a waiting state until it declares the exclusive release of the resource Rb, and the task A is in the waiting state until the task B declares the exclusive release of the resource Rb.

In this state, the resource occupation time monitoring processing function is activated at a fixed cycle (for example, a 2-second cycle),
Monitor the waiting time for tasks. If the waiting time is defined to be, for example, 10 seconds at the maximum, the waiting task in the fifth cycle is forcibly released and returned to the AP. As a result, the deadlock state is released in 10 seconds. In addition, it is possible to find out which task is in the deadlock state from the state returned to the AP.

That is, in FIG. 1A, Ri (i
= A or b) Count up the waiting timer value n in the queue (step S21), judge whether the timer value is over (step S22), and if the timer value is over, return to the AP with waiting over. Yes (step S2
3).

Further, as shown in FIG. 5, the waiting time Ti of the task waiting in each resource management queue is monitored, and if waiting is continued even after a fixed time has elapsed, A
Return to P. With this function, a response can be returned to the user within a fixed time. Furthermore, when declaring the occupation of the resource, by adding the function of designating the waiting time, it becomes possible to reply with a response that meets the user's request.

That is, in FIG. 1C, it is judged whether or not the waiting time Ti is designated in the Ri queue (step S24). If the waiting time is designated in the Ri queue, the waiting time in the task is determined. The waiting time is counted down (step S25), it is determined whether the waiting time is over (step S26), and if the waiting time is over,
Return to AP when waiting time is over (step S2)
7).

FIG. 6 is a conceptual diagram of a task. In the figure, {} means selecting either the waiting time Ti or the timer value n, and () means omittable. When {} is omitted, only the deadlock automatic cancellation performance is valid. When level i is selected, it is interpreted as level 2 (the lowest level).

[0023]

As described in detail above, according to the present invention, when declaring occupancy of a predetermined resource, the designated number of registration waits is greater than the number registered in advance for the predetermined resource. If it is large, the resource occupancy registration processing function that returns the resource unoccupied information to the application can be provided to prevent the delay of response even if the traffic is congested, thus preventing the timeout of online terminals. it can.

Further, by providing a priority for the same resource and providing a resource occupation release processing function for performing FIFO control for each level, the resource can be preferentially occupied, so that the control of the priority terminal / general terminal can be performed. it can. Furthermore, a deadlock, which is a serious failure as an online system, is automatically installed by monitoring the waiting time, and when the specified time is exceeded, a resource occupation time monitoring processing function that returns that fact to the application is provided. Can be released.

[Brief description of drawings]

FIG. 1 is a flowchart of a resource occupation registration processing function (A), a resource occupation release processing function (B), and a resource occupation time monitoring processing function (C) according to the present invention.

FIG. 2 is a conceptual diagram of resource occupation registration processing.

FIG. 3 is a conceptual diagram of resource occupation release processing.

FIG. 4 is a conceptual diagram (1) of a resource occupation time monitoring process.

FIG. 5 is a conceptual diagram (No. 2) of resource occupation time monitoring processing.

FIG. 6 is a conceptual diagram of a task.

FIG. 7 is a block diagram of an example of an online system.

FIG. 8 is a schematic view showing a conventional example.

FIG. 9 is a conceptual diagram for explaining a conventional example.

FIG. 10 is an exclusive control deadlock generation algorithm.

Claims (3)

[Claims] 1. A method for exclusive control of a common resource in a computer, wherein when declaring occupancy of a predetermined resource, a number of registration waits is designated, and the designated number is a number registered in advance for the predetermined resource. If it is larger than the above, an exclusive control method of the common resource, characterized in that the unoccupied information of the predetermined resource is returned to the application. 2. An exclusive control method for a common resource in a computer, wherein when a priority is set for the same resource and a occupancy of a predetermined resource is declared, a priority level is designated, and the designated priority level is designated in advance. An exclusive control method for a common resource, characterized in that the resource is preferentially occupied when the priority is higher than the existing priority level. 3. An exclusive control method for a common resource in a computer, wherein when a deadlock condition occurs, the waiting time is monitored, and when the waiting time exceeds a prescribed time, A common resource exclusive control method characterized by returning a message to the application to release the deadlock.