JP2600800B2 - Exclusive control of buffer table and deadlock detection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exclusive control of a buffer table and a deadlock detection method, and more particularly, to a buffer table (file update and file update) performed by a task (transaction) operating on a multitasking operating system. The present invention relates to an exclusive control of a buffer table and a deadlock detection method in a computer system in which a large number of updates are made to a part of file contents provided on a memory in order to reduce the number of times of reference.

[Conventional technology]

Conventionally, in this type of exclusive control of the buffer table, almost exclusively exclusive control is performed. That is, an exclusive key for a certain task (information such as an address specifying an area on the buffer table. The same applies hereinafter).
If the specified exclusive key is locked by another task when a buffer table update request is issued by specifying, the task that updates the buffer table with the same exclusive key was treated as an exclusive error. .

[Problems to be solved by the invention]

The conventional exclusive control method of the buffer table described above
There was no particular problem in the reference system and the update system with almost no update of the buffer table.
In an update system in which the buffer table is updated frequently, exclusion errors occur frequently, so the retry processing of tasks (transactions) increases, the load on the computer system increases, the response slows down, and the processing capacity of the computer system decreases. There is a disadvantage of doing so.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to improve the processing performance of a computer system by performing task wait control and deadlock state detection together with exclusive control of a buffer table. And a deadlock detection method.

[Means for solving the problem]

The exclusive control and deadlock detection method of the buffer table according to the present invention is applied to a computer system equipped with a multitasking operating system capable of simultaneously executing a plurality of tasks, in a task identifier, task operation state, number of exclusive cases, exclusive table link information, and wait state. A task management table for managing task-specific information including the original task number, the number of wait tasks, and the number of wait tasks, an exclusive management table for managing the number of remaining exclusive tables and the remaining exclusive table link information of the exclusive table, and updating from the task An exclusion table for registering an exclusion key specified by a request together with a next exclusion table address, and exclusion control on a buffer table on a memory using the task management table, the exclusion management table, and the exclusion table And a lock control module for task control and deadlock detection performs.

[Action]

In the exclusive control and deadlock detection method for the buffer table according to the present invention, the task management table includes a task identifier, a task operation state, an exclusive count, an exclusive table link information, a wait source task number, a wait task number, and a wait task number. Manages the information, the exclusive management table manages the number of remaining exclusive tables in the exclusive table and the remaining exclusive table link information, and the exclusive table registers the exclusive key specified in the update request from the task along with the next exclusive table address. The control module uses the task management table, the exclusion management table, and the exclusion table to perform exclusion control on the buffer table on the memory, and also performs task control and deadlock detection.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a buffer table exclusive control and deadlock detection system according to an embodiment of the present invention. The exclusive control and deadlock detection method of the buffer table according to the present embodiment includes a multitask operating system 1 capable of operating a plurality of tasks, an exclusive control module 2 including a task management table 21, an exclusive management table 22, and an exclusive table 23. , The buffer table 3 constitutes a main part thereof.

Referring to FIG. 2, the task management table 21 includes a task ID (identifier), a task operation state, the number of exclusive cases, exclusive table link information (start address and end address),
The task-specific information of the wait source task number, the number of wait tasks, and the wait task number is managed by entries in the order of the task number, and is used for task control. When the task operation state is 0, it indicates that the task is waiting, and when it is 1, it indicates that the task is operating. The wait source task number is the task number of the task that caused the invoking task to wait, the number of wait tasks is the number of tasks that are waiting due to the invoking task, and the wait task number is the wait task number due to the invoking task. Indicates the task number of the task being performed.

The exclusion management table 22 manages the number of remaining exclusion tables in the exclusion table 23 and the remaining exclusion table link information (start address and end address).

The exclusion table 23 registers a next exclusion table address and an exclusion key, and is used for exclusion check. The exclusion table 23 has a finite number n (positive integer) entries, and is managed by being chained by the next exclusion table address.

Next, the operation of the exclusive control and deadlock detection method of the buffer table of the present embodiment configured as described above will be described.

First, the outline of the operation of the exclusive control of the buffer table and the deadlock detection method of the present embodiment will be described.

When a task operating on the multitask operating system 1 requests an update of the buffer table 3 specifying an exclusive key, the exclusive control module 2 sets the exclusive key identical to the exclusive key specified in the current update request to the exclusive table. Search whether it is registered in 23. However,
The exclusion table 23 does not search all entries, but searches only the entry in which the exclusion key is registered based on the exclusion count and the exclusion table link information of the task management table 21. If the same exclusive key as the exclusive key specified in the update request is not registered in the exclusive table 23, the exclusive control module 2 determines that the exclusive key is not exclusive and registers the exclusive key in the exclusive table 23. And processes the update request while performing exclusive control. If the same exclusive key as the exclusive key specified in this update request is registered in the exclusive table 23, the exclusive control module 2
Considers the exclusive key to be exclusive and detects a deadlock state. The detection of the deadlock state is performed by referring to the task management table 21 to check the task operation state of the task whose exclusive key is exclusive, and if the task that is in the waiting state is caused by the task that issued the update request this time. Consider deadlock. If it is not in the deadlock state, the exclusive control module 2 causes the task that has issued the update request this time to wait. In the deadlock state, the exclusion control module 2 cancels (releases) all the arrangement keys that have been excluded by the task that has issued this update request, and is exclusion of the exclusion key by the task that has issued this update request. The task that was in the waiting state for the task is returned to the running state.

FIG. 3 shows a multitasking operating system 1
And three tasks A, B and C are operating and each task is a →
FIG. 13 is a diagram showing a case where an exclusive key is designated in the order of b → c → d → e → a → f → g → e → c and an update request of the buffer table 3 is made.

Next, the operation of the exclusive control of the buffer table and the operation of the deadlock detection method according to the present embodiment will be specifically described according to the order of the update request. In the initial state, the task management table 21, the exclusion management table 22, and the exclusion table 2
3 is assumed to be initially set to the contents shown in FIG.

First, the task A issues an update request for the buffer table 3 by specifying the exclusive key a. Exclusive control module 2
Searches all task-specific information in the task management table 21, and since all task-specific information has zero exclusive cases,
Immediately, the exclusive key a is registered in the first entry of the exclusive table 23. At this time, the corresponding next exclusive table address is set to "-" indicating that it is at the end of the chain (hereinafter, the update of the next exclusive table address is omitted unless it is particularly necessary). The exclusion control module 2 sets the number of exclusions in the task A and task-specific information of the task management table 21 to 1 and sets 1 and 1 to the exclusion table link information (start address and end address).
Are set respectively. Furthermore, exclusive control module 2
Subtracts 1 from the number of remaining exclusive tables in the exclusive management table 22 to (n-1), and sets the start address of the remaining exclusive table link information to 2.

Next, task B issues an update request for buffer table 3 by specifying exclusive key b. Exclusive control module 2
Searches for all task information in the task management table 21 and is registered in the exclusion table 23 linked from the start address 1 of the exclusion table link information in the task-specific information of the task A whose number of exclusions is 1 or more. Perform exclusive key search. Exclusive key b specified in this update request
Does not overlap with the exclusive key a registered in the exclusive table 23, the exclusive control module 2 refers to the exclusive management table 22 and registers the exclusive key b in the second entry of the exclusive table 23. Also, the exclusive control module 2
The number of exclusions in the task-specific information of the task B in the task management table 21 is set to 1, and the exclusion table link information (start address and end address) is set to 2 and 2, respectively. Further, the exclusion control module 2 subtracts 1 from the number of remaining exclusion tables in the exclusion management table 22 (n-
2), and the start address of the remaining exclusive table link information is 3.

Next, the task C requests the update of the buffer table 3 by specifying the exclusive key c. Exclusive control module 2
Performs the same processing as described above. As a result, the exclusion key c is registered in the third entry of the exclusion table 23, 1 is set as the number of exclusions in the task-specific information of the task C in the task management table 21, and 3 is set as the exclusion table link information (start address and end address). And 3 are respectively set, and the number of remaining exclusive tables in the exclusive management table 22 is (n
In -3), the start address of the remaining exclusive table link information is 4.

Next, the task A issues an update request for the buffer table 3 by specifying the exclusive key d. Exclusive control module 2
Performs the same processing as described above. As a result, the exclusion key d is registered in the fourth entry of the exclusion table 23, 2 is set to the number of exclusions in the task-specific information of the task A in the task management table 21, and 4 is set to the end address of the exclusion table link information. The number of remaining exclusive tables in the exclusive management table 22 is (n−4), and the start address of the remaining exclusive table link information is 5.

Next, the task B issues an update request for the buffer table 3 by specifying the exclusive key e. Exclusive control module 2
Performs the same processing as described above. As a result, the exclusion key e is registered in the fifth entry of the exclusion table 23, 2 is set as the number of exclusions in the task-specific information of the task B in the task management table 21, and 5 is set as the end address of the exclusion table link information. The number of remaining exclusive tables in the exclusive management table 22 is (n-5), and the start address of the remaining exclusive table link information is 6.

Next, the task C issues an update request for the buffer table 3 by specifying the exclusive key a. Exclusive control module 2
Performs the same processing as described above, and sets the exclusive key a to the task A
Detects that it is exclusive. Therefore, the exclusive control module 2 checks the task operation state in the task-by-task information of the task A in the task management table 21, determines that the task A is in operation, and determines that the task A is not in the deadlock state, and causes the task C to wait. (See Figure 3)
In the task management table 21, 1 is set to the number of wait tasks in the task-specific information of the task A, and task number 3 of the task C is set to the wait task number. The exclusive control module 2 also checks the task C in the task management table 21.
In the task-by-task information, "0" indicating "waiting" is set as the task operation state, and task number 1 of task A is set as the wait source task number (see FIG. 4).

Next, the task A issues an update request for the buffer table 3 by specifying the exclusive key f. Exclusive control module 2
Performs the same processing as described above. As a result, the exclusion key f is registered in the sixth entry of the exclusion table 23, 3 is set as the number of exclusions in the task-specific information of the task A in the task management table 21, and 6 is set as the end address of the exclusion table link information. The number of remaining exclusive tables in the exclusive management table 22 is (n-6), and the start address of the remaining exclusive table link information is 7.

Next, the task B issues an update request for the buffer table 3 by specifying the exclusive key g. Exclusive control module 2
Performs the same processing as described above. As a result, the exclusion key g is registered in the seventh entry of the exclusion table 23, 3 is set as the number of exclusions in the task-specific information of the task B in the task management table 21, and 7 is set as the end address of the exclusion table link information. The number of remaining exclusive tables in the exclusive management table 22 is (n-7), and the start address of the remaining exclusive table link information is 8 (see FIG. 4).

Next, the task A requests the update of the buffer table 3 by designating the exclusive key e. Exclusive control module 2
Performs the same processing as described above, and sets the exclusive key e to the task B
Detects that it is exclusive. Therefore, the exclusive control module 2 checks the task operation state in the task-by-task information of the task B in the task management table 21, determines that the task B is in operation, and determines that the task B is not in the deadlock state, and waits for the task A. (See Figure 3)
The number of wait tasks in the task-specific information of the task B in the task management table 21 is set to 1, and the wait task number is set to the task number 1 of the task A. In addition, the exclusive control module 2 executes the task A in the task management table 21.
In the task-by-task information, "0" indicating "waiting" is set in the task operation state, and task number 2 of task B is set in the wait source task number (see FIG. 4).

Next, the task B issues an update request for the buffer table 3 by specifying the exclusive key c. Exclusive control module 2
Performs the same processing as described above, and sets the exclusive key c to the task C
Detects that it is exclusive. Therefore, the exclusive control module 2 checks the task operation state in the task-specific information of the task C in the task management table 21, and since it is 0 indicating that the task is being waited, the task A in the task management table 21 is determined based on the wait source task number 1. Check the task operation state in the task-specific information of. Since the task operation state in the task-by-task information of the task A is also 0 indicating that the task is waiting, the exclusive control module 2 considers that a deadlock state has been detected (see FIG. 3). Therefore, exclusive control module 2
Cancels all exclusive keys b, e, and g that are exclusive in task B that has issued the current update request, and exclusive key c specified in the current update request. That is, the exclusion control module 2 deletes the registration of the exclusion keys b, e, and g in the exclusion table 23, and incorporates the entry of the exclusion table 23 from which the registration of the exclusion keys b, e, and g has been deleted into the chain of the remaining exclusion table. Therefore, the next exclusive table address is replaced, the number of remaining exclusive tables in the exclusive management table 22 is updated to (n-4), and the start address and end address of the remaining exclusive table link information are updated to 9 and 7, respectively. Further, the exclusion control module 2 sets the task operation state in the task management table 21 of the task A, which is waiting for exclusion in the task B that has issued the update request this time, to 1 and returns it to the operation state. As a result, a process of updating the buffer table 3 specifying the exclusive key e from the task A is performed (see FIG. 5). That is, the exclusive control module 2 performs the same processing as described above, and as a result,
The exclusion key e is registered in the eighth entry of the exclusion table 23, 4 is set as the number of exclusions in the task-specific information of the task A in the task management table 21, and 8 is set as the end address of the exclusion table link information. table
The remaining exclusive table number of 22 is (n-5), and the start address of the remaining exclusive table link information is 9.

Next, the task B designates the canceled exclusive key b and makes a request to update the buffer table 3 again (fifth request).
See figure). The exclusive control module 2 performs the same processing as described above. As a result, the exclusion key b is registered in the ninth entry of the exclusion table 23, the exclusion number in the task-specific information of the task B in the task management table 21 is 1, and the exclusion table link information (start address and end address).
Are set to 9 and 9, respectively.
Of the remaining exclusive table is (n-6), and the start address of the remaining exclusive table link information is 10 (see FIG. 6).

Next, the task B specifies the canceled exclusive key e and makes a request to update the buffer table 3 again (fifth request).
See figure). The exclusion control module 2 performs the same processing as described above, and detects that the exclusion key e is being exclusioned by the task A. Therefore, the exclusive control module 2 checks the task operation state in the task-by-task information of the task A in the task management table 21, determines that the task A is in operation, and determines that the task A is not in the deadlock state, and waits for the task B. Therefore, 1 is added to the number of wait tasks in the task-specific information of the task A in the task management table 21 to obtain 2, and the wait task number is assigned to the task number 2 of the task B.
Add. In addition, the exclusive control module 2 sets “0” indicating “waiting” in the task operation state and “task number 1” of the task A as the wait source task number in the task-specific information of the task B in the task management table 21 (sixth task).
See figure).

Hereinafter, similarly, the update request of the buffer table 3 specifying the exclusive keys g and c from the task B is also processed, but the details thereof are omitted.

〔The invention's effect〕

As described above, the present invention has an effect that the processing capability of the computer system can be improved by performing the exclusive control of the buffer table, the wait control of the task, and the detection of the deadlock state together.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a buffer table exclusive control and deadlock detection system according to an embodiment of the present invention. FIG. 2 is a diagram showing a task management table, an exclusive management table and an exclusive table in FIG. FIG. 3 is a diagram showing an example of a deadlock state in the multitasking operating system; FIG. 4 is a diagram exemplifying the contents of a task management table, an exclusion management table, and an exclusion table in the deadlock state shown in FIG. FIG. 5 is a diagram showing the state after the deadlock shown in FIG. 3, and FIG. 6 exemplifies the contents of the task management table, the exclusion management table, and the exclusion table in the state after the deadlock shown in FIG. FIG. In the figure, 1 is a multitask operating system, 2 is an exclusive control module, 3 is a buffer table, 21 is a task management table, 22 is an exclusive management table, and 23 is an exclusive table.

Claims (1)

(57) [Claims] In a computer system having a multitask operating system capable of simultaneously executing a plurality of tasks, a task identifier, a task operation state, an exclusion count, an exclusion table link information, a wait source task number, a wait task count, and a wait task are provided. A task management table that manages task-specific information including numbers, an exclusive management table that manages the number of remaining exclusive tables in the exclusive table and the remaining exclusive table link information, and an exclusive key specified by an update request from the task. The exclusive table to be registered together with the table address, the task management table, the exclusive management table, and exclusive control of the buffer table on the memory using the exclusive table, and task control and deadlock detection are performed. And an exclusive control module for the buffer table.