JPH06309213A - Rollback control system - Google Patents

Abstract

PURPOSE:To improve the efficiency of transaction processing by performing partial rollback processing and omitting unnecessary rollback processing and re-execution processing. CONSTITUTION:A program state saving means 13 saves a program state in a state saving area 30 when a saving point is passed, generates resource control information 40 corresponding to resource access at the time of resource access, and relates the state saving area 30 corresponding to a saving point right before the resource access is performed to the resource control information 40. A deadlock detecting means 12 detects whether or not a deadlock is caused owing to the resource access at the time of the resource access. When the deadlock is detected, the resource relating to the deadlock is rolled back to the state of the saving point regarding the resource access relating to the deadlock. A program state restoring means 14 restores the program state to the state of a saving point as the return point of the rollback.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rollback control system for controlling rollback when a deadlock is detected in the process of transaction processing which constitutes a transaction processing program.

[0002]

2. Description of the Related Art Conventionally, this type of rollback control system relates to resource access (resource update, etc.) performed by a transaction process when the occurrence of a deadlock is detected in the process of the transaction process. All resources were rolled back to the state at the beginning of the transaction processing, and the transaction processing was restarted after the rollback. That is, the rollback related to the resource access irrelevant to the deadlock is also the target of the rollback at the time of detecting the occurrence of the deadlock.

In the prior art related to the present invention, there is a transaction backout simple processing system (Japanese Patent Laid-Open No. Hei.
No. 264336), there is a method in which a restart address when a failure such as a deadlock occurs is designated in advance and transaction processing is restarted from the restart address when a failure such as a deadlock occurs. According to this method, it is possible to avoid the waste of rolling back all the resources to the first state of transaction processing. But,
Even with this method, when a deadlock is detected, it is not possible to judge a resource for which rollback can be omitted or to detect an optimum return address in rollback. Therefore, even if this method is used to control rollback when detecting the occurrence of deadlock,
There is no change in that "resource access unrelated to deadlock is subject to rollback".

[0004]

In the above-described conventional rollback control method, resource access irrelevant to the deadlock is also rolled in the rollback control when the occurrence of deadlock is detected in the process of transaction processing. Since it is targeted for backing, unnecessary rollback processing is performed, and it is necessary to re-execute resource access regardless of deadlock after transaction processing is restarted, which hinders improvement in transaction processing efficiency. There was a flaw.

In view of the above points, an object of the present invention is to perform a partial rollback in order to omit unnecessary rollback processing and re-execution processing, so that transaction processing (particularly deadlock occurs). It is to provide a rollback control method (which can be called a “partial rollback control method because partial rollback is performed”) that can improve the efficiency of easy transaction processing.

[0006]

The rollback control method of the present invention comprises a state save area securing / releasing means for securing a state save area at the start of a transaction processing program and releasing the state save area at the end of the transaction processing program. , The state save area corresponding to the save point immediately before the resource access is executed by saving the program state at that point in the state save area when passing the save point and creating the resource management information corresponding to the resource access at the time of resource access And a program state saving means for associating the resource management information with the resource management information, and deadlock detection means for detecting whether or not a deadlock occurs due to the resource access at the time of accessing the resource,
When the deadlock detection means detects the occurrence of a deadlock, the deadlock is placed in the state of the save point corresponding to the state save area associated with the resource management information corresponding to the resource access related to the deadlock. Rollback means for rolling back resources related to
Program state recovery means for recovering the program state to the state of the save point at the destination of rollback by this rollback means, and transaction such as recognition of passage of the save point and restart of transaction processing after rollback and program state recovery And an execution control means for controlling the execution of the process.

Further, in the rollback control method of the present invention, after the resource related to the deadlock is rolled back, the exclusive lock of the other transaction process which is not related to the deadlock occurs in the resource locked by the own transaction process. The deadlock detecting means for detecting whether there is not, and the resource management information corresponding to the resource access related to the exclusive weight when the deadlock detecting means detects the exclusive weight of other transaction processing not related to the deadlock. It is also possible to provide the rollback means for rolling back the resource associated with the exclusive weight to the state of the save point corresponding to the state save area associated with.

Further, in the rollback control method of the present invention, the state save area is not secured at the start of the transaction processing program and the state save area is not released at the end of the transaction processing program, and the save is performed when the save point is passed. The state save area corresponding to the point is secured, the state save area corresponding to all the save points in the transaction process is released at the normal end of the transaction process, and at the time of rollback, when the save point at the return destination of the rollback is passed. It is also possible to provide the state save area securing / releasing means for releasing the state save area secured later.

[0009]

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

First, a first embodiment of the rollback control system of the present invention (an embodiment corresponding to the invention of claim 1).
Will be described.

FIG. 1 is a block diagram showing the configuration of the rollback control system (rollback control system 10) of this embodiment.

The transaction processing program in FIG. 1 is a program including one or more transaction processing. This transaction processing program includes a rollback control method 10 and a state save area 30.
And resource management information 40 that manages resource access (the resource to be accessed is the access resource 20).

Each transaction process in the transaction processing program is provided with one or more save points (program state save points) (a description indicating the save points exists in the source program of the transaction processing program). .

The rollback control system 10 includes an execution control means 11, a deadlock detection means 12, a program state saving means 13, a program state recovery means 14, a state saving area securing / releasing means 15, and a rollback means. 16
It is configured to include and.

The state save area 30 includes a program state save area 31 in which a program state (contents of registers and variables, etc.) at the time of passing a save point provided during transaction processing is saved, and a self state save area 30. Information indicating the resource management information 40 created at the time of resource access that occurs between the corresponding save points and the next save points (for example, when the resource management information 40 is configured in a chain structure, the resource management at the head of the chain) Resource information 32 having a pointer to the information 40 and a pointer to the final resource management information 40). One state save area 30 is required for each passing of the save points.

The resource management information 40 is created at the time of resource access by the transaction processing in the transaction processing program, and reflects the content (image) of the access resource 20 at the time of the resource access (information indicating the content itself or log information, etc.). ) Is stored.

FIGS. 2A and 2B are views for explaining the specific operation of the rollback control system of this embodiment.

Next, the operation of the rollback control system (rollback control system 10) of the present embodiment having such a configuration will be described.

The state save area securing / releasing means 15 has a number of states equal to or more than the number of passing save points that are expected to occur in the processing process of all transaction processes included in the transaction processing program when the transaction processing program is started. Reserve area 30 is secured.

The execution control means 11 controls the execution of each transaction process and notifies the program state saving means 13 of that (passage of the save point) when the save point is passed during transaction processing.

The program state saving means 13 stores the program state (contents of registers and variables, etc.) at that point in the state save area 30 when the save point is passed (when the above-mentioned notification is received from the execution control means 11). Saves to one (thus, one state save area 30 exists corresponding to one passage of the save point).

Further, the execution control means 11 has a deadlock detecting means 12 and a program state saving means 13 at the time of resource access which occurs in the process of transaction processing.
To that effect.

Upon receiving the notification, the program state saving means 13 performs the following processing. Resource management information 40 (information reflecting the contents of the access resource 20 at that time) corresponding to the resource access is created. Information indicating the save point immediately before the execution of the resource access is set in the resource management information 40. Specifically, a pointer to the state save area 30 corresponding to the save point is set in the resource management information 40. The resource information 32 in the state save area 30 (state save area 30 corresponding to the save point immediately before the execution of the resource access) is updated to indicate the existence of the resource management information 40. Specifically, the "pointer to the final resource management information 40" in the resource information 32 is updated to the "pointer to the resource management information 40" (chain information in the resource management information 40 is also maintained).

By the above processes (1) and (2), the state save area 30 corresponding to the save point immediately before the execution of the resource access can be associated with the resource management information 40.

Upon receiving the above notification, the deadlock detection means 12 detects whether or not a deadlock has occurred due to the resource access.

When the deadlock detecting means 12 detects the occurrence of deadlock, it passes control to the rollback means 16 via the execution control means 11.

The rollback means 16 detects a resource access associated with a deadlock that has occurred (this detection can be accomplished by conventional techniques) and is associated with the resource management information 40 corresponding to that resource access. The resource related to the deadlock (the access resource 20 corresponding to the resource management information 40) is rolled back to the state of the save point corresponding to the state save area 30. At the time of this rollback, the information in the resource information 32 in the state save area 30 and the chain information in the resource management information 40 are used to follow some resource management information 40 in the reverse order of the resource access occurrence order.

Further, the program state recovery means 14 is
The state save area 3 corresponding to the save point so that the program state is restored to the state of the save point at the rollback return destination
The information (program state) in the program state save area 31 in 0 is restored to registers and variables.

The execution control means 11 restarts the transaction processing from the save point.

The state save area securing / releasing means 15 is
At the end of the transaction processing program shown in FIG. 1, all state save areas 30 are released.

Next, with reference to FIGS. 2A and 2B, a specific operation of the rollback control system (rollback control system 10) of this embodiment will be described.

A first transaction process (hereinafter referred to as TX1) in a certain transaction processing program and a second transaction process (hereinafter referred to as TX2) in another transaction processing program are operating at the same time, and those processes are performed. Consider the operation when a deadlock occurs in TX1 in the process of.

In this case, the flow of operation leading to the occurrence of deadlock is as follows (see FIG. 2 (a)).

(1) The TX 1 saves the program state in the state save area 30 when passing a certain save point (referred to as save point (1)).

(2) Similarly, the TX 2 saves the program state in the state save area 30 when passing through a certain save point (referred to as save point (2)).

(3) The TX1 creates the resource management information 40 corresponding to the resource access (3) at the time of access to the resource A (referred to as resource access (3)), and saves it with the resource management information 40. The state save area 30 corresponding to the point (1) is associated.

(4) On the other hand, the TX 2 creates the resource management information 40 corresponding to the resource access (4) when accessing the resource C (referred to as resource access (4)), and the resource management information 40 And the state save area 30 corresponding to the save point (2).

(5) TX1 passes through the first save point (referred to as save point (5)) after resource access (3),
The program state is saved in the state save area 30.

(6) Similarly, the TX2 saves the program state in the state save area 30 when the first save point after the resource access (4) (pass point (6)) is passed.

(7) The TX1 creates the resource management information 40 corresponding to the resource access (7) when accessing the resource B (referred to as the resource access (7)), and saves the resource management information 40 with the resource management information 40. The state save area 30 corresponding to the point (5) is associated.

(8) The TX2 accesses the resource B by the TX1 (resource access (7)) and then the resource B
However, since the access to the resource B by TX1 has already been performed, the exclusive wait state is set.

(9) When TX1 passes through the first save point (referred to as save point (9)) after resource access (7),
The program state is saved in the state save area 30.

(10) After the above processes (1) to (9) are advanced, the TX1 attempts to access the resource C. At this time, the resource C is being accessed by the TX2 (see (4)), and the TX2 is in the exclusive wait state in the process of trying to access the resource B after accessing the resource C (see (8)). . Therefore, at this point, the deadlock detecting means 12 in the TX 1 detects the occurrence of deadlock. In this case, the “resource access related to the deadlock” is the resource access (7).

TX after detection of occurrence of deadlock
The operation of No. 1 is as follows (see FIG. 2B).

(A) Roll back the resource B to the state of the save point (5). As a result, the exclusive wait state of TX2 is released.

(B) The program state in the program state save area 31 in the state save area 30 corresponding to the save point (5) is restored to registers and variables.

After the rollback and the program state recovery as described above, the TX1 restarts the processing from the access of the resource B.

Further, since the resource B is rolled back by the TX1, the TX2 can access the resource B, and the TX2 can continue the subsequent processing.

Second, a second embodiment of the rollback control system of the present invention (an embodiment corresponding to the invention of claim 2).
Will be described.

FIG. 1 is also a block diagram showing the configuration and the like of the rollback control system of the second embodiment (there are some constituent elements having different processing contents between the first embodiment and the second embodiment). However, components having the same name shall be denoted by the same reference numeral).

FIGS. 3A and 3B are views for explaining the specific operation of the rollback control system of this embodiment.

Next, the operation of the rollback control system (rollback control system 10) of the present embodiment having such a configuration will be described.

The basic operation is the same as the operation of the first embodiment described above. The following points are the operations peculiar to the second embodiment.

The deadlock detecting means 12 rolls back resources related to deadlock (rollback means 1).
In the resource locked (exclusively accessed) by the own transaction process (transaction process in which the deadlock detection means 12 exists) after the rollback by 6, the exclusive wait of the other transaction process that is not related to the deadlock is Detect if it has not occurred.

When the deadlock detection means 12 detects the exclusive weight of another transaction process not related to the deadlock, the rollback means 16 is related to the resource management information 40 corresponding to the resource access related to the exclusive weight. A resource associated with the exclusive weight in the state of the save point corresponding to the attached state save area 30 (the access resource 20 corresponding to the resource management information 40)
To roll back.

With the peculiar operation as described above, in the second embodiment, the rollback control can be performed in consideration of the influence on the other transaction processing not related to the deadlock.

Next, the specific operation of the rollback control system (rollback control system 10) of this embodiment will be described with reference to FIGS.

A first transaction processing (hereinafter referred to as TX1) in a certain transaction processing program, a second transaction processing (hereinafter referred to as TX2) in another transaction processing program, and a third transaction processing in yet another transaction processing program. Transaction processing (hereinafter referred to as TX3) of the same is operating at the same time, and deadlock (TX
Consider the operation when a deadlock between 1 and TX2 occurs.

The flow of operation up to the occurrence of deadlock in this case is as follows (see FIG. 3 (a)).

(1) to (8) are the same as in the case of FIG.

(9) The TX 3 saves the program state in the state save area 30 when passing through a certain save point (referred to as save point (9)).

(10) TX3 is the resource A by TX1
After the access to the resource A (resource access (3)), an attempt is made to access the resource A, but since the access to the resource A by TX1 has already been performed, the exclusive wait state is set.

(11) TX1 is resource access (7)
At the time of passing the first save point (referred to as save point (11)) after, the save of the program state to the state save area 30 is performed.

(12) After the above processes (1) to (11) are advanced, TX1 tries to access the resource C. At this time, the resource C is being accessed by the TX2 (see (4)), and the TX2 is the resource C.
In the process of trying to access the resource B after the access to (see (8)), the exclusive wait state is set.
Therefore, at this point, the deadlock detection means 12 in the TX1 detects the occurrence of a deadlock ("resource access related to the deadlock" is resource access (7)).

TX after detection of occurrence of deadlock
The operation of No. 1 is as follows (see FIG. 3B).

(B) Roll back the resource B to the state of the save point (5). As a result, the exclusive wait state of TX2 is released.

(B) Roll back the resource A to the state of the save point (1). As a result, the exclusive wait state of TX3 is released. The save point (1) is used for other transaction processing (TX
State save area 3 associated with resource access (resource access (3)) related to the exclusive weight in 3)
This corresponds to the save point corresponding to 0.

(C) The program state in the program state save area 31 in the state save area 30 corresponding to the save point (1) is restored to registers and variables.

After the rollback and the program state recovery as described above, the TX1 restarts the processing from the access of the resource A.

Since the resource B is rolled back by the TX1, the TX2 can access the resource B, and the TX2 can continue the subsequent processing.

Further, since the resource A is rolled back by the TX1, the TX3 can access the resource A, and the TX3 can access the resource (10).
The subsequent processing can be immediately performed.

Thirdly, a third embodiment of the rollback control system of the present invention (an embodiment corresponding to the invention of claim 3).
Will be described.

FIG. 1 is also a block diagram showing the configuration and the like of the rollback control system of the third embodiment (there are some constituent elements having different processing contents between the first and third embodiments). However, components having the same name shall be denoted by the same reference numeral).

FIGS. 4A and 4B are views for explaining the specific operation of the rollback control system of this embodiment.

Next, the operation of the rollback control system (rollback control system 10) of the present embodiment having such a configuration will be described.

The basic operation is the same as that of the first embodiment described above. The following points are the operation peculiar to the third embodiment which is different from the first embodiment.

In the first embodiment, the state save area reserving / releasing means 15 is sufficient to deal with the execution of all transaction processes in the transaction processing program at the start of the transaction processing program.
And the state save area 30 is released at the end of the transaction processing program.

On the other hand, this embodiment (third embodiment)
Then, the state save area securing / releasing means 15 secures the state save area 30 corresponding to the save point when the save point is passed.

Further, in this embodiment, the state save area securing / releasing means 15 carries out the following processing for releasing the state save area 30.

When a transaction process is normally completed and a commit is performed, the state save area 30 corresponding to all save points (correctly, all “pass points”) in the transaction process. To release.

When rollback (partial rollback) is performed, the state save area 30 secured after the passing of the save point at the return destination of the rollback is released.

By the peculiar operation as described above, in the third embodiment, it becomes possible to reduce the memory resident amount necessary for securing the state save area 30.

Next, with reference to FIGS. 4A and 4B, a concrete operation of the rollback control system (rollback control system 10) of this embodiment will be described.

A first transaction process (hereinafter referred to as TX1) in a certain transaction processing program and a second transaction process (hereinafter referred to as TX2) in another transaction processing program are operating at the same time, and those processes are performed. Consider the operation when a deadlock occurs in TX1 in the process of.

The flow of operation up to the occurrence of deadlock is the same as in the case of FIG. 2 (a). However, when each evacuation point is passed, the state evacuation area 30 corresponding to the evacuation point is secured (see FIG. 4A).

TX after detection of occurrence of deadlock
The operation of No. 1 is as follows (see FIG. 4B).

(A) Roll back the resource B to the state of the save point (5). As a result, the exclusive wait state of TX2 is released.

(B) The state save area 30 corresponding to the save point (9) (the state save area 30 secured after passing the save point (5)) is released.

(C) The program state in the program state save area 31 in the state save area 30 corresponding to the save point (5) is restored to registers and variables.

By securing and releasing the state save area 30 as described above, it becomes possible to reduce the memory resident amount required for securing the state save area 30.

In the rollback control method of the second embodiment, it is possible to realize the rollback control method of securing and releasing the state save area 30 by the method of the third embodiment. Such a rollback control method
It corresponds to the invention of claim 4.

[0092]

As described above, according to the present invention, unnecessary rollback processing and re-execution processing can be omitted by excluding resource access irrelevant to deadlock from rollback. It has an effect that the efficiency of processing can be improved.

Further, by performing the above-mentioned rollback control in consideration of the exclusive wait in the other transaction processing which is not related to the deadlock, the effect of the deadlock on the other transaction processing can be reduced while obtaining the above effect. There is an effect that can be done.

Furthermore, by ensuring and releasing the state save area necessary for obtaining the above-mentioned effect (the effect of "enhancing the efficiency of transaction processing") at a high frequency, in order to secure the state save area. There is an effect that the above-mentioned effect can be obtained even if the required memory resident amount is small.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration and the like of first to third embodiments of a rollback control system of the present invention.

FIG. 2 is a diagram for explaining a specific operation of the first embodiment of the rollback control system of the present invention.

FIG. 3 is a diagram for explaining a specific operation of the second embodiment of the rollback control system of the present invention.

FIG. 4 is a diagram for explaining a specific operation of the third embodiment of the rollback control system of the present invention.

[Explanation of symbols]

 10 Rollback Control Method 11 Execution Control Means 12 Deadlock Detection Means 13 Program State Saving Means 14 Program State Restoring Means 15 State Saving Area Securing / Release Means 16 Rollback Means 20 Access Resources 30 State Saving Areas 31 Program State Saving Areas 32 Resources Information 40 Resource management information

Claims (4)

[Claims] 1. A state save area securement that secures a state save area at the start of a transaction processing program and releases the state save area at the end of a transaction processing program.
The release means and the program state at that point in time when the save point is passed are saved in the state save area, the resource management information corresponding to the resource access is created at the time of resource access, and the save point is set just before the resource access is executed. Program state saving means for associating the corresponding state save area with the resource management information, deadlock detecting means for detecting whether a deadlock occurs due to the resource access at the time of resource access, and this deadlock When the detection means detects the occurrence of a deadlock, the state of the save point corresponding to the state save area associated with the resource management information corresponding to the resource access related to the deadlock is related to the deadlock. Rollback means for rolling back resources and the save point for the rollback return destination by this rollback means The program state recovery means for recovering the program state to the above state, and the execution control means for recognizing the passage of the save point and controlling the execution of the transaction processing such as the rollback and the restart of the transaction processing after the program state recovery. A rollback control method characterized in that 2. The dead that detects, after the rollback of the resource related to the deadlock, whether or not the exclusive lock of the other transaction process that is not related to the deadlock has occurred in the resource locked by the own transaction process. Lock detection means and state saving associated with resource management information corresponding to resource access related to the exclusive weight when the exclusive lock of other transaction processing not related to the deadlock is detected by the deadlock detection means The rollback control system according to claim 1, further comprising: rollback means for rolling back a resource associated with the exclusive weight in a state of a save point corresponding to the area. 3. A state save area at the start of a transaction processing program and a state save area at the end of a transaction processing program are not released, and a state save area corresponding to the save point is secured when the save point is passed. Then, at the normal end of the transaction process, the state save area corresponding to all the save points in the transaction process is released, and at the time of rollback, the state save that is secured after the save point at the return destination of the rollback is passed. 2. The rollback control system according to claim 1, further comprising a state save area securing / releasing means for releasing a zone. 4. A state save area at the start of a transaction processing program and a state save area at the end of a transaction processing program are not released, but a state save area corresponding to the save point is secured when the save point is passed. Then, at the normal end of the transaction process, the state save area corresponding to all the save points in the transaction process is released, and at the time of rollback, the state save that is secured after the save point at the return destination of the rollback is passed. 3. The rollback control system according to claim 2, further comprising means for securing / releasing the state save area for releasing the area.