JPH03260734A - Resources control system for computer system - Google Patents

Abstract

PURPOSE:To reduce the influence of a wrong resources securing request to the system operation by performing forcibly the resources securing end processing after a prescribed time set by the program priority, etc., when a resources waiting state occurs. CONSTITUTION:An invent buffer 1 controls the resources to the resources securing requests given from the programs 2A - 2X for the functions A - X of an application program respectively. The resources distribution deciding parts 41 - 43 decide the resources waiting times to each resources securing request by using the program priority and the resources occupation rate or the resources importance as parameters. A timer 3 starts to count the time against the resources securing request and then starts a resources securing end processing part 5 when the time counting action of the timer 3 is first coincident with the waiting times decided by the parts 41 - 43 respectively. Thus the security of resources is forcibly ended via the time control decided by the program priority when a resources waiting state occurs. As a result, a semipermanent waiting state of the program is eliminated even with occurrence of the deadlock. Then a computer system can be carried on.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a resource management method for a computer system, and more particularly to a deadlock avoidance method.

B1 Summary of the Invention The present invention provides a resource management method in which a resource management program allocates each resource of a system in response to a resource reservation request from an application program, in which resources are secured after a time determined by program priority when a resource wait occurs. By forcibly performing completion processing, the impact on system operation due to erroneous resource reservation requests is reduced.

C1 Conventional technology A peripheral device that becomes a resource for a computer system.

To manage files, memory, etc., a resource management program is prepared that accepts requests to secure resources necessary for executing many application programs and releases the resources when the execution ends.

The conventional management method is to register resource reservation requests from application programs in a resource request queue sequentially or in the order of the priority of each program.
rst In FirstOut), and releases the resources in accordance with the resource release request of the program.

In such resource management programs, there is a problem of system deadlock. This deadlock occurs when multiple programs make a mistake in the order in which they request to secure resources. For example, as shown in Figure 2, in a state where program A has secured resource X and program B has secured resource Y, when program A requests to secure resource Y in the next process, program B When a request is made to secure X, both programs A and B enter a semi-permanent waiting state (frozen state) until the other party releases the secured resources.

Although attempts are made to avoid the occurrence of the deadlock described above at the system design stage, there is a possibility that it will remain as a bug as the system becomes larger. Although the impact is small, if a paralyzing situation develops and spreads, there is a risk that the entire system will be unable to function (system down).

Conventional deadlock avoidance methods include all-or-nothing methods in which no resources are secured unless all necessary resources are secured. For example, in FIG. 2, when program A requests to secure resource Y, if program B has already secured resource Y, program A cannot secure resource Y, so it also releases resource X, and as a result, program B program A can secure both resources Y and X to execute its processing, and program A can secure both resources X and Y after program B completes its processing.

D1 Problem to be solved by the invention In the conventional deadlock avoidance method, a program that cannot secure resources releases all resources, so the program is placed in a waiting state until the resources it uses are exhausted or are released. . Therefore, when applied to an online system, there is a problem that it causes problems such as inoperability.

For example, when a conventional put-lock avoidance method is applied to a power system monitoring and control system, a program that displays a system diagram for monitoring CRT equipment cannot secure the resource CRT and enters a waiting state with all resources released. It becomes impossible to monitor the power system, and it becomes impossible to know changes in equipment status during that time.

Furthermore, conventional resource management methods do not handle requests for duplicative resource allocation. This duplicate reservation request occurs when the same program mistakenly requests the same resource twice due to a bug, etc., and the resource management program handles the second resource request as unable to allocate the resource. The program will be in a state of waiting for resources semi-permanently.

An object of the present invention is to provide a resource management method that reduces the influence of erroneous resource reservation requests on system operation.

Means and Effects for Solving Problem E1 In order to achieve the above object, the present invention provides resource management in which a resource management program allocates and releases each resource in response to resource reservation requests from a plurality of application programs. In the method, the resource management program includes a timer that measures time from the occurrence of resource waiting in response to the resource reservation request, and a priority, resource occupancy, resource importance, and resource reservation order of the program in response to the resource reservation request. and a determination unit that determines the resource waiting time using parameters such as the above, and when the time determined by the determination unit matches the time measured by the timer, the resource reservation completion process is forcibly performed, and the resource waiting time due to deadlock is prevented. After the time determined by the determination unit at the time of occurrence, the resource reservation is forcibly completed and the processing of each program is executed, and the semi-permanent waiting state of the resource is released.
To ensure system operation even when some programs run out of resources.

F. Embodiment FIG. 1 is a functional configuration diagram of a resource management program showing an embodiment of the present invention. The event buffer l is a program 2A to 2 for each function A to X of the application program.
Performs resource management in response to requests from X to secure resources. This resource management is performed according to FIFO as in the past.

In addition to the above-mentioned resource management, the event buffer l has a deadlock avoidance function when a deadlock occurs due to a resource reservation request from programs 2A to 2x becoming a reverse order request, and a resource waiting release function for resource duplicate requests from the same program. Equipped with functions.

The wait release function by the event buffer 1 ignores FIFO-based management for resource duplication requests and responds to the program with the completion of resource reservation.

Through this processing, the program is released from waiting for resources and continues processing.

Next, the deadlock avoidance function using the event buffer l, time management using the timer 3, and resource allocation determination I'L4.
- 43 etc., resource allocation is determined by consistency management, and deadlock avoidance is realized by performing resource reservation completion processing 5 according to this determination.

Time management by the timer 3 starts counting time in response to a resource reservation request from an arbitrary program, and the timer 3
This is used for comparison with the time determined by discrimination based on I-48, etc. Discrimination unit 4. 43 obtains the resource waiting time as the determination result, and uses the program priority determination unit 4.4 as the determination parameter. Then, it is determined from the priority order of the program that made the resource reservation request, and the resource occupancy rate determination unit 4. Then, the occupancy rate of the resource used by the program in one process is determined, and the resource importance determination unit 43 determines the importance of the resource (influence on other programs). Note that other parameters (not shown) are determined based on the relationship with the resource reservation order, etc., and these discrimination parameters are appropriately determined from the contents of the application program, and respective discrimination units are provided.

The above-mentioned discrimination unit 4. -43, the resource reservation completion processing unit 5 is activated when the time measured by the timer 3 first matches. Whether this process 5 is a normal response process or an abnormal response process may be determined based on parameters, as in the case of the discrimination section.

Therefore, in the resource management in this embodiment, when a resource wait occurs in normal resource management, the resource reservation is forcibly completed after a period of time determined from the priority of the program concerned, etc. It will be resolved after waiting an appropriate amount of time determined by . At this time, some programs will be processed without some resources, but deadlocks and system downs will be reliably avoided. In addition, in the case of duplicate requests, resource allocation becomes normal and normal processing can be resumed.

Effects of the G9 Invention As described above, according to the present invention, when a resource wait occurs, resource reservation is forcibly completed by time management determined by program priority, etc., so even when a put lock occurs, the program does not have to wait semi-permanently. This has the effect of eliminating the problem and allowing the system to continue operating.

In particular, it is effective when applied to online systems to reliably prevent system failures due to resource waiting and improve system reliability.

[Brief explanation of drawings]

FIG. 1 is a functional configuration diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of deadlock. ■...Event buffer, 2A, 2X...Program, 3...Timer, 4°4, . 43...Discrimination unit, 5...Resource reservation completion processing unit. 2 people not included in the explanation diagram for Puttlock

Claims (1)

[Claims] (1) In a resource management method in which a resource management program allocates and releases each resource in response to resource reservation requests from multiple application programs, the resource management program waits for resources in response to the resource reservation request. a timer that measures time from the occurrence of the resource reservation request, and a determination unit that determines the resource waiting time using parameters such as the priority of the program, the resource occupancy rate, the resource importance, the resource reservation order, etc. for the resource reservation request, and the determination unit A resource management method for a computer system, characterized in that a resource reservation completion process is forcibly performed when the time measured by the timer matches a time determined by the department.