JPH10240553A - Exclusive control system and method for resource for distributed transaction processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade locking contention between different processes relating to the same transaction in a system for distributing and processing the transaction by the plural processes. SOLUTION: Plural processors capable of performing communication with each other divide resources 15 and 18 and are in charge of them. The system is provided with a GTAP(global transaction application) 11 for issuing a locking request to the plural resources (a) and (c) to be updated/referred to by one transaction T, LTAPs(local transaction applications) 12, 13 and 16 for executing the locking processing of the resources (a) and (c) in response to the locking request and locking tables 14 and 17 for indicating a locking state for the respective resources. When the locking request is received, the respective LTAPs refer to the locking tables 14 and 17 first, check the presence/absence of the locking contention with the other LTAPs for processing the same transaction T for the resources (a) and (c) of a locking object, perform adjustment and perform locking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a transaction processing system such as a banking system and a reservation system, and more particularly to a transaction distributed processing system in which one transaction is processed by a plurality of processes in a distributed manner. Of exclusive control when a process accesses the same resource.

[0002]

2. Description of the Related Art In a system in which a plurality of processes (or a plurality of message processing devices) distribute and process one input message (transaction), resources are mutually exclusive so that a plurality of processes do not simultaneously update the same resource in a database. Normally, control (that is, setting (locking) and release (unlocking) of an exclusive state) is performed.

FIG. 1 is a block diagram showing an exclusive control system in a conventional transaction distributed processing system.

FIG. 1 shows three message processing apparatuses 1 connected via a LAN (local area network).
The lock request and the processing for the request are performed among a, 1b, and 1c. Here, the lock request unit 2 is a process for requesting a lock on a resource to be accessed, and the lock processing units 3a, 3b, 3c are processes for executing a lock on the resource in response to the lock request. Tables a in databases 5 and 7
“b” and “c” are examples of the minimum unit in which exclusive control of resources can be performed.

In this system, for example, in order to execute one global transaction, the first message processing device 1a sends three lock requests for three local transactions T1, T2, T3 constituting the same global transaction. And the third message processing device 1b, 1c. And two local transactions T1,
It is assumed that the lock request at T2 is for the same table a of the database 5 in the second message processing device 1b. In this case, the second message processing device 1b
Lock processing units 3 and 4 responding to one lock request
However, an attempt is made to execute locks on the same table a, but these locks conflict and one of the locks cannot be executed. Therefore, although two local transactions T1 and T2 are derived from the same global transaction, one of them is aborted (rolled back), and as a result, the global transaction cannot be committed.

Here, a global transaction is a transaction that involves updating a plurality of distributed resources, and is composed of a plurality of local transactions. A local transaction is a transaction that involves accessing (ie, updating or referencing) only one resource.

FIG. 2 is a block diagram showing a conventional exclusive control system which solves the above-mentioned problem.

In the system shown in FIG. 2, the first message processing device 1a includes two local transactions T1, T
When 2 is for updating the same table a, two lock requests for the same table a are sent to a single lock processing unit 3 in the second message processing device 1b.
Since the single lock processing unit 3 sequentially executes the locks in response to the two lock requests sequentially, no lock conflict occurs, and the global transaction is committed without any trouble.

[0009]

In the exclusive control system shown in FIG. 2, when issuing a plurality of lock requests for the same resource, the lock request unit 2 must always designate a single lock processing unit. For this reason, the program of the lock requesting unit 2 must be created in consideration of the resources in each message processing device in advance, and there is a problem that it takes time to create the program.

Accordingly, an object of the present invention is to provide a system in which a plurality of processes processes a single transaction in a distributed manner, thereby avoiding lock contention between different processes for processing the same transaction with a simple program configuration. It is to make.

[0011]

According to the present invention, there is provided an exclusive access control method for resources for a distributed transaction processing system, in which a plurality of lock processes relating to a plurality of resource accesses to be performed in one transaction are individually performed. A plurality of lock processing means for performing, and a lock table indicating a lock state of the resource, wherein each of the lock processing means receives a lock request for a specific resource and refers to the lock table,
Means for determining whether or not the specific resource has already been locked by another lock processing means associated with the same transaction; and, if the determination result is affirmative, the lock request is sent to the other lock processing means. An exclusive resource control method is provided that includes a transfer unit and a unit that locks the specific resource when the determination result is negative.

The present invention also relates to a method for exclusive control of access to resources for a distributed transaction processing system, wherein a plurality of lock processes for individually performing a plurality of lock processes relating to a plurality of resource accesses to be performed in one transaction. Comprises processes, each of which attempts to lock a particular resource,
Determining whether or not the specific resource is already locked by another process related to the same transaction; and, if the determination result is positive, requesting the other process to lock the specific resource. A resource exclusive control method comprising: a step of locking the specific resource when the result of the determination is negative.

Further, in the distributed transaction processing system, the present invention provides a global transaction processing means for executing a global transaction and a plurality of local transaction processing for individually executing a plurality of local transactions constituting the global transaction. Means for issuing a lock request for a plurality of resource accesses to be performed in the global transaction to each of the plurality of local transactions, and wherein each of the local transaction processing means Receiving the lock request, executing another local transaction related to the same global transaction. Means for determining whether or not a lock is in conflict for the same resource, and means for transferring the lock request received by itself to the other local transaction processing means if the result of this determination is affirmative. And a distributed transaction processing system having:

Still further, according to the present invention, in a transaction distributed processing method, there are provided a plurality of processes for individually executing a plurality of local transactions constituting a global transaction.
When trying to lock a resource for each local transaction, it is determined whether or not lock contention for the same resource is in conflict with another process executing another local transaction related to the same global transaction. And a step of requesting the other process to execute its own local transaction when the result of this determination is affirmative.

According to the present invention, individual processes that execute lock processing check for lock contention on the same resource between other processes involved in the same transaction, and if there is lock contention, one of the processes performs the lock contention. Lock contention is avoided by coordinating to perform conflicting locks. Therefore, in order to avoid lock contention, it is not necessary for the process requesting the lock to be aware of resource contention. The present invention is typically realized by a computer, and a computer program therefor can be installed or loaded on the computer through various media such as a disk storage, a semiconductor memory, and a communication network.

[0016]

FIG. 3 is a block diagram of a distributed transaction processing system according to an embodiment of the present invention. FIG. 3 shows a specific example in which a lock request and a lock process are performed between three message processing devices 10a, 10b, and 10c connected via a LAN.

The three message processing devices 10a, 10b, 10
c, a data table managed by each, a lock table for indicating a lock state of each data table for each table, a GTAP (global transaction application) which is an application for executing a global transaction, GTAP
LTAP (local transaction application), which is an application for executing individual local transactions in response to a request from a local transaction.

In the specific example of FIG. 3, the first message processing device 1
In order to execute a certain global transaction T, three local transactions T constituting the global transaction T
Three lock requests for T1, T2 and T3 are issued to the second and third message processing devices 10b and 10c. Of these, the lock requests for the two local transactions T1 and T2 are both for the same table a in the data table 15 of the second message processing device 10b, and are both sent to the second message processing device 10b. Have been.
Another lock request is for the table c in the data table 18 in the third message processing device 10c, and is therefore sent to the third message processing device 10c.

In the second message processing device 10b, two LTAPs (local transaction applications) 12, 13 respond to the two lock requests, respectively.
Is running. Each of the two LTAPs 12 and 13 refers to the lock table 14 and checks the lock state of the same table a to be locked. If LTAP 12 performs this check earlier than LTAP 13, LTAP 12
(Specifically, the lock information indicating that the table a is locked is written in the lock table 14), so that the other LTAP 13 cannot lock the table a. Then, the LTAP 13 determines that the local transaction T1 executed by the LTAP 12 that has locked the same table a is the same global transaction T as its own local transaction T2.
Check if it is derived from As a result, if they are the same, the LTAP 13 transfers the lock request received by itself to the other LTAP 12. The LTAP 12 that has received this transfer makes its own local transaction T
After executing step 1, the table a is locked again in response to the transferred lock request, and the local transaction T2 is executed. Therefore, the two local transactions T1 and T2 are committed without causing a lock contention problem.

In the third message processing device 10c, one LTAP 16 is activated in response to the lock request, and the LTAP 16 locks the table c and executes the local transaction T3.

As a result, the global transaction T is committed.

FIGS. 4 and 5 show the GT in this system.
7 shows a flow of processing of an AP and an LTAP that has received a lock request from GATP. In both figures, a thin arrow line connecting the blocks indicates the flow of processing, and a thick arrow line indicates the flow of a message.

As shown in FIG. 4, when a GTAP starts a certain global transaction, first, a step S
In step 1, a lock request message of each local transaction constituting the global transaction is created, and the lock request message is issued to the LTAP of the message processing device that is in charge of the resource to be locked. When issuing a lock request message, the message may be addressed to any LTAP in the message processing device, that is, a specific LTAP
Need not be specified.

The LTAP that has received the lock request message retrieves the lock state of the resource to be locked from the lock table in step S2, and determines in step S3 whether or not there is a lock conflict, that is, the lock has already been locked. It is determined whether or not. As a result, if the target resource has not been locked yet, in step S4, lock information indicating that the target resource has been locked is written to the lock table 14 (that is, the target resource is locked). Then, control goes to a step S8 described later.

On the other hand, if the result of the determination in step S3 indicates that the target resource has already been locked, that is, if the lock is in conflict, the LTAP determines in step S5 that the local transaction (ie, the target It is determined whether or not the local transaction that is currently locking the resource) is related to the same global transaction as its own local transaction. The lock information written in the lock table 14 includes the identifier of the local transaction that has performed the lock, and also includes the identifier of the original global transaction. It can be determined whether or not the transaction is related to a global transaction.

If the result of this determination is that they do not relate to the same global transaction, the LTAP moves to step S9, which will be described later. On the other hand, if the locks are related to the same global transaction, the LTAP determines in step S6 whether or not the lock is a lock performed by its own process (also determined from the local transaction identifier included in the lock information). it can). As a result, when the lock is performed by the own process, the process proceeds to step S8 described later.

If the result of determination in step S6 is that the lock has been performed by another process, LTAP determines in step S7
Then, the lock processing message received by itself is transferred to the other LTAP that has performed the lock. The other LTAPs that have received the transfer repeat the processing of step S2 and subsequent steps again in response to the transferred lock request after the processing of the local transaction related to the lock currently being executed is completed.

In step S8, the LTAP notifies the GTAP that issued the lock request of a lock result indicating that the lock was successful. When proceeding to step S9, L
The TAP notifies the GTAP that issued the lock request of the lock result indicating that the lock has failed. In either case,
The identification of the LTAP that has performed the lock processing is added to the lock result. GTAP receives the lock result in step S10. LTA added to the lock result
By identifying P, the GTAP can know the LTAP that has executed the lock processing.

Next, as shown in FIG. 5, in step S11, the GTAP receives the lock results for all the issued lock requests, and determines whether all the lock results are successful in locking. If all locks have succeeded, the process proceeds to step S12, in which an update / reference request message for executing update / reference to each locked resource is created, and the message is transferred to the LT that has locked the resource.
Send to AP (specified by LTAP identification included in lock result).

LTAP receiving update / reference request message
Executes the update / reference for the corresponding resource in step S13, and returns the update / reference result to the GTAP in step S14. The GTAP receives the update / reference result from each LTAP in step S15, and if all the update / reference results are successful, creates a commit message for each local transaction in step S16, and
It transmits to each referenced LATP.

Each LTAP receiving the commit message,
In step S17, the commit of each local transaction is executed, and the unlock of each resource is executed (that is, the lock information is deleted from the lock table or the unlock information is written in the lock table). GTA the commit result in S18
Notify P. The GTAP receives the commit result in step S19, and ends the global transaction if it receives the commit results of all the local transactions.

If it is determined in step S11 that any one of the resources has failed in locking, the GTAP
Shifts to the rollback processing of the global transaction in step S20, creates a rollback message of all the local transactions in step S16, and sends it to each LTAP. Subsequent step S1
The processing contents 7 and below are contents in which “commit” of the processing at the time of commit described above is replaced with “rollback”.

According to the present system, a process (LTA) for executing lock processing (or local transaction)
P) detects a lock conflict within the same global transaction before performing the lock, and transfers the lock request to another process (LTAP) that has previously locked the lock if the conflict occurs. Therefore, since the process (GTAP) requesting the lock can avoid the lock conflict without being aware of the resource conflict, it is easier to create a program than before.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an exclusive control method of a distributed transaction processing system according to a conventional example.

FIG. 2 is a block diagram showing an exclusive control method of a distributed transaction processing system according to another conventional example.

FIG. 3 is a block diagram illustrating an exclusive control method of the distributed transaction processing system according to the embodiment of the present invention.

FIG. 4 is a first half of a process flow chart in the system shown in FIG. 3;

FIG. 5 is a latter half of a process flow chart in the system shown in FIG. 3;

[Explanation of symbols]

 10a First message processing device 10b Second message processing device 10c Third message processing device 11 GTAP 12, 13, 16 LTAP 14, 17 Lock table 15, 18 Data table

Claims (6)

[Claims] An exclusive control method for access to resources for a distributed transaction processing system, comprising: a plurality of lock processing means for individually performing a plurality of lock processes relating to a plurality of resource accesses to be performed in one transaction; A lock table indicating a lock state of the resource, wherein each of the lock processing means receives a lock request for a specific resource, and refers to the lock table to thereby obtain another lock processing means related to the same transaction. Means for determining whether the specific resource is already locked, means for transferring the lock request to the other lock processing means if the result of the determination is affirmative, and means for negating the result of the determination The means for locking the specific resource. Vinegar exclusive control system. 2. A method for exclusive control of access to resources for a distributed transaction processing system, comprising: a plurality of processes for individually performing a plurality of lock processes related to a plurality of resource accesses to be performed in one transaction; Each of a plurality of processes, when trying to lock a specific resource, determining whether or not the specific resource is already locked by another process associated with the same transaction; and In this case, a resource exclusive control method comprising: requesting the other process to lock the specific resource; and locking the specific resource when the result of the determination is negative. 3. In a distributed transaction processing system, a global transaction processing means for executing a global transaction, a plurality of local transaction processing means for individually executing a plurality of local transactions constituting the global transaction, The global transaction processing means has means for issuing a lock request for a plurality of resource accesses to be performed in the global transaction to the plurality of local transactions, respectively, wherein each of the local transaction processing means When receiving the lock request, another local transaction processing means for executing another local transaction related to the same global transaction, Means for judging whether or not lock conflicts occur for the same resource, and means for transferring the received lock request to the other local transaction processing means if the result of the judgment is affirmative. Distributed transaction processing system. 4. A distributed transaction processing method, comprising a plurality of processes for individually executing a plurality of local transactions constituting a global transaction, wherein each of the processes attempts to lock resources for each local transaction. When to determine, between another process executing another local transaction related to the same global transaction, a step of determining whether or not lock contention for the same resource, If the result of the determination is affirmative, Requesting the other process to execute its own local transaction. 5. A computer-readable recording medium having a program for causing a computer to execute a method for exclusive control of access to resources for a distributed transaction processing system, wherein the method should be performed in one transaction. A plurality of processes that individually perform a plurality of lock processes related to a plurality of resource accesses, wherein each of the plurality of processes is to lock a specific resource by another process associated with the same transaction. A step of determining whether or not the resource is already locked; and a step of, if the determination result is affirmative, requesting the other process to lock the specific resource; and a step of, if the determination result is negative, the Locking specific resources Recording medium. 6. A computer-readable recording medium carrying a program for causing a computer to execute a distributed transaction processing method, the method comprising: a plurality of processes for individually executing a plurality of local transactions constituting a global transaction Each of the processes, when trying to lock resources for each local transaction, has a lock on the same resource with another process executing another local transaction related to the same global transaction. A recording medium comprising: a step of determining whether or not there is a conflict; and, if the result of the determination is affirmative, requesting the other process to execute its own local transaction.