JPH0934851A - Multi-cluster exclusive controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-cluster exclusive controller in which the performance of the entire system is improved by executing dead lock monitor processing only for a dead lock case. SOLUTION: This controller is provided with a lock block name storage means 7 storing common data or file identifier accessed exclusively, a lock process name storage means 8 storing a process name accessed exclusively corresponding to the identifier, a wait process name storage means 9 storing an awaited process name with respect to the identifier when the exclusive access is awaited, a lock wait time monitor mechanism 5 monitoring a wait time of the awaited process, and a dead lock monitor device 6 starting the investigation whether or not a deal lock wait takes place after the monitored wait time reaches a specified time or over.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer system composed of a plurality of hosts, and more particularly to a multi-cluster exclusive control device for exclusive control of access to shared data or files between hosts.

[0002]

2. Description of the Related Art A conventional multi-cluster exclusive control device is
When exclusively accessing a shared data or file, if the shared data or file to be accessed is already exclusively accessed by another process, it is immediately checked whether a deadlock wait occurs. .

That is, when, for example, the first process in a certain host tries to exclusively access the shared data or file, another second process has already accessed the shared data or file. If it was locked, the access of the first process is made to wait until the lock is released, but at that time, it was always investigated immediately whether a deadlock wait occurred. For this reason, it is necessary to investigate whether deadlock waiting occurs or not at a frequency much higher than in the case of actually waiting for deadlock, which significantly reduces the performance of the entire system.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the performance of the entire system by executing deadlock monitoring processing only in the case of deadlock.

[0005]

In a multi-cluster exclusive control device according to the present invention, lock block name storage means for storing an identifier for identifying shared data or file to be exclusively accessed, and the shared data or file are excluded. A request for exclusive access is made to the lock process name storage means for storing the process name of the process to be accessed in a corresponding manner and the shared data or file, but the shared data or file is In the case of waiting for access due to exclusive access by another process, wait process name storage means for storing the process name of the process to be waited for in correspondence with the identifier, and waiting for the access. Lock waiting time monitoring means for monitoring the waiting time when
After the monitored waiting time exceeds the specified time,
A deadlock monitoring start means for starting an investigation as to whether a deadlock wait has occurred is provided.

The lock block name storage means, the lock process name storage means, and the wait process name storage means are preferably formed on the memory in association with each other so that writing and reading can be performed efficiently.

According to the present invention, when an access request of a certain process is made to wait, after a certain period of time, the investigation as to whether or not a deadlock wait is occurring is started, so that almost deadlock occurs. The deadlock monitoring process can be executed only in the case.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an example in which two hosts 2.3 are connected to a multi-cluster exclusive control device 1 according to the present invention. When accessing the file shared between the hosts, each of the hosts 2 and 3 first notifies the multi-cluster exclusive control device 1 of the file name and the process name of the process issuing the access request.

The multi-cluster exclusive control device 1 has an exclusive control unit 4, a lock waiting time monitoring mechanism 5, a deadlock monitoring mechanism 6 and three items of recording means 7. 8. 9. These storage means 7, 8 and 9 have a file name of a file for which an exclusive access request has been requested, a process name of a process which has issued the request and is permitted access, and the access request which has been issued. The process name of the process waiting for is stored in association with the process name by the identifier. In one embodiment of the present invention, these storage means are constructed on a chain table which is expanded on the memory as shown in FIG. 3, but the details will be described later.

The exclusive control unit 4 is composed of a microprocessor, receives an access request to a file from each host 2 and 3, and uses the storage means 7. 8. 9 to determine whether the access request can be granted. And the information in the storage means 7, 8 and 9 is updated. Further, as a result of the determination of the access request, the exclusive control unit 4 causes the lock waiting time monitoring mechanism 6 to wait for the access request.
A process name of the access request source and a pointer indicating an entry for storing the process in the wait process name storage unit 9 are notified.

The lock waiting time monitoring mechanism 5 monitors the waiting time when a process waits for access to a shared file, and notifies the deadlock monitoring mechanism 6 when the waiting time reaches a prescribed time or longer. To do. Details of the lock waiting time monitoring mechanism 5 will be described later with reference to FIG. The deadlock monitoring mechanism 6 is composed of a microprocessor, and investigates whether a deadlock wait occurs by using the storage means 7, 8 and 9. In FIG. 1, reference numerals 100 to 106 denote signal lines.

FIG. 2 shows an aspect in which a deadlock wait occurs. The process 1 tries to access the shared file A, but the file is kept waiting because the process 2 is already accessing it. Process 2 tried to access shared file B,
The file is waiting for access because process 1 is already accessing it. In this state, since both process 1 and process 2 have been waiting for processing, neither shared file A nor shared file B is released, and both processes cannot proceed.

FIG. 3 shows the storage means 7, 8 and 9 shown in FIG.
2 shows an example of the structure of FIG. The present embodiment has a field for storing a file name which is the lock block name shown in FIG. 1, a field for storing a lock process name, a field for storing a wait process name and a field for storing a pointer indicating the next entry. It has an entry for each file name being accessed and stores it in memory.

When each host 2/3 notifies the exclusive control unit 4 of the file name requesting access and the process name of the requesting source, the exclusive control unit 4 requests the lock block name storage field of the above entry. Search whether the file name is stored. If not stored, the file name is written in the lock block name storage field, the requesting process name is written in the lock process name storage field, and it is stored in the memory as a new entry. The address of the memory that stores the new entry is written in the pointer field to the next entry, and the access permission is notified to the access request source host. As a result of the above search,
If the requested file name is stored, the process name of the request source is written in the wait process name storage field of the entry storing the requested file name, the address of the memory storing the entry, and the request source process. The lock waiting time monitoring mechanism 5 is notified that a name and a waiting process have occurred.

When the access to the shared file of the process is completed, each host 2/3 notifies the exclusive control unit 4 of the release of the file. The exclusive control unit 4 searches for an entry that stores the released file name. If nothing is stored in the wait process name storage field of the entry related to this search, the entry stores the pointer field of the entry indicating the entry as the next entry in order to delete the entry. Rewrite to the pointer value. That is, the first
If the entry is the second entry among the second, third, and third entries, the pointer value stored in the first entry is changed to the first entry when deleting the second entry. The third entry is replaced with the pointer value shown as the next entry, and the entry having the third pointer value of the first entry is shown as the next entry.

If the wait process name storage field of the entry stores the process name waiting for access, the process name stored in the wait process name storage field is set to the lock process name storage field of the entry. , The host having the process is notified of permission to access the shared file, and the lock waiting time monitoring mechanism 5 is notified of release of the process name and access waiting to the shared file.

FIG. 4 shows the lock waiting time monitoring mechanism 5 of FIG.
2 shows an internal circuit of the first embodiment. Lock wait time monitoring mechanism 5
Is composed of a plurality of remaining time monitoring circuits 10 and a selection circuit 11 for selecting its output. Each remaining time monitoring circuit 10 includes a first and second register 12 and 13, and a -1 decrementer 14 that decrements the contents of the second register 13 by -1.
A comparator 15 is provided for comparing whether the output of the -1 decrementer 14 is equal to 0 and, if they are equal, outputting a logical value of 1. The first register 12 stores a wait process name notified from the exclusive control unit 4 of FIG. 1, a memory address storing the wait process name, and an identification bit indicating that there is valid information. To do. The second register 14 stores the remaining time as viewed from the specified value of the process access waiting time. Then, the lock waiting time monitoring mechanism 5 selects the information of the register 12 in the remaining time monitoring circuit 10 when the output value of the comparator 15 is the logical value 1 among the outputs of the plurality of remaining time monitoring circuits 10. Circuit 1
1 is used to notify the deadlock monitoring mechanism 6 of FIG.

That is, when the exclusive control unit 4 of FIG. 1 notifies the lock waiting time monitoring mechanism 5 that a process waiting for access to a shared file has occurred, a plurality of remaining time monitoring circuits 10 Search the identification bit of the register 12 to detect the remaining time monitoring circuit 10 that does not hold valid information, enable the identification bit of the register 12 in the remaining time monitoring circuit 10, and notify from the exclusive control unit 4. The process name for which the access is waited for and the memory address of the entry storing the process name are stored in the register 12, and a prescribed value is set in the register 13. After that, the value of the register 13 is set to -1 for each machine cycle.
Decrementer 14 decrements by 1 and comparator 15 decrements by 1.
When it is detected, the information in the register 12 is output to the deadlock monitoring mechanism 6 through the selection circuit 11.

When the lock waiting time monitoring mechanism 5 is notified by the exclusive control unit 4 that the process wait for access to a file has been canceled, the process name of the access wait notified by the exclusive control unit 4 is set. Detecting the remaining time monitoring circuit 10 having the held register 12 and invalidating the identification bit of the register 12 of the remaining time monitoring circuit 10,
The update of the register 13 is suppressed.

In this embodiment, the circuit in FIG. 4 is composed of the register, the -1 decrementer, the comparator, and the selection circuit, but it is obvious that the same processing can be carried out even if it is composed of the memory and the microprocessor. Is.

The deadlock monitoring mechanism 6 of FIG. 1 is composed of a microprocessor, and deadlock monitoring is performed by the lock waiting time monitoring mechanism 5 of FIG. When notified to the mechanism 6, the deadlock monitoring mechanism 6 inhibits the access from the exclusive control unit 5 to the respective storage means 7/8/9, and waits for the deadlock by using the storage means 7/8/9. The investigation is started on the basis of the program on the microprocessor to see if the occurrence has occurred.

[0022]

According to the present invention, when the process concerned has exclusive access to the shared data or file, another process has already accessed the shared data or file. When waiting, after a certain period of time has passed, the investigation to see if a deadlock wait is occurring is started, so the deadlock monitoring process will be executed only in the case of almost deadlock. Performance improvement can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing one aspect of deadlock wait occurrence.

FIG. 3 is a diagram showing a configuration example of a storage unit in FIG.

FIG. 4 is a block diagram showing an embodiment of a remaining time monitoring mechanism in FIG.

[Explanation of symbols]

 1 Multi-cluster Exclusive Control Device 2.3 Host 4 Exclusive Control Unit 5 Lock Wait Time Monitoring Mechanism 6 Deadlock Monitoring Mechanism 7 Lock Block Name Storage Means 8 Lock Process Name Storage Means 9 Wait Process Name Storage Means

Claims (2)

[Claims] 1. A multi-cluster exclusive control device for performing exclusive control of access to shared data or files among a plurality of hosts, and lock block name storage means for storing an identifier of shared data or files to be exclusively accessed. A lock process name storing means for storing a process name that exclusively accesses the shared data or file in correspondence with the identifier, and a wait process when exclusive access to the shared data or file is waited. Wait process name storage means for storing the process name to be stored corresponding to the above identifier, lock waiting time monitoring means for monitoring the waiting time of the waiting process, and after the monitored waiting time exceeds the specified time. Has a deadlock monitoring start method that starts investigation to see if a deadlock wait has occurred. Multi-cluster exclusive control device according to claim Rukoto. 2. The multi-cluster exclusive control device according to claim 1, wherein lock block name storage means, lock process name storage means, and wait process name storage means are associated with each other and formed on a memory.