JP2853608B2 - File access control method of parallel processing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel processing system having a file shared by each host, and more particularly, to a file access control method of a parallel processing system for improving concurrent execution of transaction processing.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open Nos. Hei 5-216742 (parallel processing method and apparatus) and Japanese Unexamined Patent Publication No. Hei 2-144637 (Japanese Patent Laid-Open Publication No. Hei 2-144637) disclose, for example, Japanese Patent Application Laid-Open Nos. Access method to data structure), JP-A-63-2653
No. 54 (data processing conflict management method).

[0003] Japanese Patent Application Laid-Open No. 5-216742 discloses a method in which an extended area is used as a large-capacity calculation storage area shared by a plurality of processing units, and a large-scale distributed processing of a plurality of processing units can be performed. Is disclosed. JP 2
Japanese Patent Application Publication No. 144637 discloses an access method in which reading is performed without a lock in a parallel processing system, thereby eliminating overhead associated with the lock. JP 63
JP-265354 discloses a method in which records of two files are defined in the same format, and when contention between writing and reading occurs, one is selected for writing and the other is selected for reading to perform parallel processing. In each of these conventional methods,
In any case, lock control is always required at the time of write processing.

[0004]

When the above-mentioned conventional method is applied to a parallel processing system, a lock control capable of controlling the entire parallel processing system is required, and a large overhead for the lock control occurs, and There is a problem that state management (weight graph management) of the entire parallel system for deadlock check due to occurrence of a wait state is required. In addition, it is necessary to lock all the time, including writing to the file, which hinders the concurrency of transaction processing.

An object of the present invention is to provide a file access control method of a parallel processing system capable of improving the throughput of data processing and improving the concurrent execution of data processing by reducing the overhead due to file exclusion control. To provide.

[0006]

To achieve the above object, the present invention provides a parallel processing system for simultaneously accessing a shared file from each host via a shared buffer.
On the shared buffer, a reference buffer for page reference and an update buffer for page update are provided, and for each page in the reference buffer, version information of the corresponding page, information indicating an updater, and information indicating the number of referenceers When setting a page and updating a page, a new version of the page is created in the update buffer without updating the existing page in the reference buffer. It is configured to have access means.

In another aspect, the version information is used to perform consistent data access between pages,
The updater information is used to restrict simultaneous updates to the same page, the referrer number information is used to release the reference buffer, and the number of referrers is set to “0” in cases other than the current page. When the current page is reached, it is released only when the number of referrers is "0" and the current page is the same as the current page and there is no old version page.

In another preferred aspect, the shared file access means retrieves a necessary page from the reference buffer when referring to a page, and refers to the reference buffer if a referrer is referring to the reference buffer. A page input processing unit that refers to the update buffer only when the referrer is updating, and when a required page does not exist, allocates a reference buffer to the shared buffer and inputs a required page from the shared file; At times,
When the updater is updating the page, the update buffer is made updatable, when another person is updating, an error occurs, and when there is no updater, the relevant page is copied from the reference buffer to the update buffer. , And a page update processing unit for setting the update buffer in an updatable state.

In another preferred aspect, the shared file access means outputs the update buffer being updated by itself to the shared file during the commit processing, replaces the updated buffer as the current page of the reference buffer, and further updates the reference buffer. A commit processing unit that sets the state of no updater and subtracts “1” from the number of referrers, and at the time of error processing, discards the update buffer being updated by itself and leaves the reference buffer without an updater. In addition to the setting, when an update or reference is being performed by itself, an error processing unit that subtracts “1” from the number of referrers in the reference buffer is provided.

[0010] In another preferred aspect, the page input processing section allocates a reference buffer and, if the version of the page input from the shared file matches the version of the required page, reduces the number of viewers of the page. "1" is added, and if the versions do not match, an error is generated. If the same page as the required page being referred to by another exists in the reference buffer, if the version of the page matches, the referrer of the page Add "1" to the number,
If the versions do not match, a reference buffer is allocated to the shared buffer and a necessary page is input from the shared file.

[0011]

According to the file access control method of the parallel processing system of the present invention, the shared file access means has a reference buffer and an update buffer separately on the shared buffer, and has exclusive control on the shared buffer. Is performed, the lock control for each page is not required. Since the lock control on a page-by-page basis is unnecessary, a wait state does not occur, a wait graph management is also unnecessary, and a long-time lock during file input / output is not generated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, a parallel processing system according to an embodiment of the present invention
, Shared file access means 20 and exclusive control means 3
0, a resource management device 40, a shared buffer 50, and a shared file 60.

The shared file access unit 20 includes a page input processing unit 21, a page update processing unit 22, a commit processing unit 23, and an error processing unit 24, and is a means for controlling and managing the shared buffer 50. Exclusive control means 30
This is used by the shared file access unit 20 to perform exclusive control on the shared buffer 50. The resource management device 40 is a device used by the exclusive control unit 30 to perform exclusive control of the entire parallel processing system.

The shared buffer 50 includes a reference buffer 51
And an update buffer 52, and the buffer is managed by the shared file access unit 20. The reference buffer 51 has, as management information for each buffer, version information B indicating the version of the corresponding page, updater information U indicating an update transaction, and reference number information R indicating the number of reference transactions for each page.

These pieces of information are used by the shared file access means 20 to perform exclusive control on the shared buffer 50. As the version information B, for example, time stamp information is used. An update date and time for each page is set, and control is performed so as not to access a page image updated after the activation date and time of each transaction. To avoid inconsistency.

The updater information U is used to restrict simultaneous update to the same page or to permit only the updater to refer to the buffer being updated. Reference The number information R is used to release the buffers of the reference buffer 51, Bae
The latest version of the page in the per-page reference buffer.
In the case of a page other than the current page, when the value of the number of viewers becomes “0”, the buffer is released by LRU control or the like. In the case of the current page, the value of the number of viewers is “0”.
And if there is no page of the same version as the current page and an old version, the buffer is released. The shared file 60 is a file shared by the parallel processing system.

Here, an example of the state of the shared buffer 50 will be described with reference to page A shown in FIG. In FIG. 1, the latest committed version of page A is version “2”, and version 2 of page A is simultaneously referenced by a total of three transactions of two reference transactions other than the update transaction “P” at this time. ing. Further, the version "1" of the previous generation is stored in the reference buffer 51, and is used to process data of the same version in synchronization with another page. The version “3” of the page A on the update buffer 52 is being updated by the update transaction “P”.

FIGS. 2 to 55 show flowcharts of the page input processing unit 21, the page renewal processing unit 22, the commit processing unit 23, and the error processing unit 24 in the shared file access unit 20. Regarding the operation of the present invention,
This will be described with reference to FIG. 1 and FIGS. First, an outline of the operation will be described with reference to FIG.

When the transaction P updates the shared file 60, the shared file access means 20
Performs an update on the update buffer 52 by storing the current page image of the page to be updated in the reference buffer 51 and securing an update buffer in the update buffer 52. Before transaction P performs commit processing
If another transaction is performing the process of referring to the shared file 60 referring to the current Bae Jiimeji
Thus , the update transaction P and the reference of another transaction can be executed simultaneously.

FIG. 2 shows the contents of buffer control when referring to data in the shared file 60, which is the operation of the page input processing section 21 of the shared file access means 20.

When referring to data, a necessary page is first searched from the reference buffer 51 (step 201). Only when the necessary page exists and the referrer is updating (step 202), the update buffer 52 is referred to (step 208). Reference buffer is present and the reference user to reference the buffer if in reference to the reference buffer (step 202).

[0022] If the viewers about the need page is neither in the reference even while update (step 202), searches whether the same page exists (step 203). If the same page exists, the version and transaction
Compare with the start date and time of the action and update it before the start date and time.
If the page is the same version, it is determined that the page is of the same version (step 204). If the page is the same version, "1" is added to the number-of-referred-to information R (step 207).

If there is no page of the same version (steps 203 and 204), an attempt is made to allocate a reference buffer and input from the shared file 60 (step 2).
05). If only a newer version than the required version can be input, the reference transaction is reprocessed as an error (step 206). When the required version is input (step 206), "1" is added to the number-of-referencer information R of the reference buffer to be referred (step 207). With the above processing, the reference processing in the transaction is executed without contradiction.

However, in the case of counting by referring to a large amount of data, when update transactions are arriving one after another, the version does not match (step 206) and the counting process is repeated many times, so that the process may not be completed. It can happen. To handle such cases,
It is necessary to issue a commit several times during the tallying process to advance the tallying process.

FIG. 3 shows buffer control at the time of updating data in the shared file 60, which is the operation of the page update processing unit 22 of the shared file access means 20.

At the time of updating data, if the update transaction has not input an updated page, the page input process described with reference to FIG. 2 is performed (step 301). Of course, if the updated page is held in the buffer, the processing of step 301 is not required.

If the updater is already updating the page, the update buffer is set to be updated (step 302). If the updater is not updating (including the case where the page input process is performed), if another person is updating the page, an error occurs and the page is reprocessed (step 303). That is, the process is rolled back and the process is restarted from the commit time.

If the page exists in the reference buffer 51 but the other person is not updating, the information of the update transaction is set in the updater information U of the reference buffer (that is, the state is set to the state of updating itself). Yes), data is copied from the reference buffer to the update buffer, and the update buffer is made updatable (step 304). In other words, an update other than the current page (the latest page) is set as an error, and control is performed such that an update to the current page is permitted only when the update has not been performed or when another updater has already updated the update.

With respect to the overhead in the lock control at the time of updating, which is a drawback of the conventional method, this embodiment manages the update transaction on the shared buffer and restricts the update transaction for the same page to only one. Is unnecessary.

FIG. 4 shows buffer control at the time of commit, which is the operation of the commit processing unit 23 of the shared file access means 20.

The commit is a self transaction reference searching buffer (step 401), the reference buffer is present and commit issuer updating the page
In the case of (402, 403), the update buffer is output to the shared file 60 (step 404). Further, the update buffer is replaced as the current page of the reference buffer (step 405), and the reference buffer is changed to the updated state (step 406). That is, the updater information U in the reference buffer is set to a state without an updater.
Thereafter, the referrer number information in the referrer buffer is reduced by "1" (step 407).

If the commit issuer is referencing the reference buffer (steps 401, 402, 403), "1" is reduced from the referrer number information (step 407), and the reference in which the referrer number is "0" is obtained. The buffer is a buffer to be released by LRU control or the like.

FIG. 5 shows the operation of the error processing unit 24 of the shared file access means 20 to control the buffer when an error occurs.

When an error occurs, the error creator discards the update buffer being updated (steps 501, 502, 50).
3, 504), the updater of the reference buffer is changed to a state of no update (step 505), and the number of reference transactions (number of referencers) is reduced by 1 (step 506). When the error occurrence person is referring to the reference buffer (steps 501, 502, 503), "1" is reduced from the number of the reference persons (step 406).

When an error occurs, only the update buffer is discarded and the file need not be rolled back.
Keep only the latest committed data on the file,
This is because only a shared buffer holds multiple versions of data.

The exclusive control for simultaneous access to the shared buffer 50 is performed by using the exclusive control means 30, if necessary. The exclusion control means 30 performs exclusion control using a resource management device 40 that controls exclusion processing of the entire parallel processing system. Alternatively, there is a method of having a test and set instruction as a basic synchronization instruction on a shared buffer and performing exclusive control, a method of performing exclusive control using communication means between hosts, and the like. Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments.

[0037]

As described above, according to the present invention, in a parallel processing system, exclusive control is performed on memory management of a shared buffer, and lock control in units of pages is not required. By enabling parallel processing and reducing the waiting time due to exclusive control, it is possible to improve the throughput of data processing and the degree of parallel processing, and to cope with a system of mass data processing.

Regarding the overhead in the lock control at the time of update, the update control is managed on the shared buffer, and the lock control can be made unnecessary by restricting only one update transaction to the same page.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a parallel processing system according to one embodiment of the present invention.

FIG. 2 is a flowchart illustrating processing performed by a page input processing unit of a shared file access unit according to the embodiment.

FIG. 3 is a flowchart illustrating processing performed by a page update processing unit of the shared file access unit according to the embodiment.

FIG. 4 is a flowchart illustrating processing performed by a commit processing unit of the shared file access unit according to the embodiment.

FIG. 5 is a flowchart illustrating processing performed by an error processing unit of the shared file access unit according to the embodiment.

[Explanation of symbols]

 10-1 to 10-n Host 20 Shared file access unit 21 Page input processing unit 22 Page update processing unit 23 Commit processing unit 24 Error processing unit 30 Exclusive control unit 40 Resource management device 50 Shared buffer 51 Reference buffer 52 Update buffer 60 Shared File

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 1-319837 (JP, A) JP-A 62-287359 (JP, A) JP-A 3-246644 (JP, A) JP-A 3- 123946 (JP, A) JP-A-1-161452 (JP, A) JP-A-1-163848 (JP, A) JP-A-3-24648 (JP, A) JP-A-4-284548 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G06F 12/00 G06F 3/06 G06F 9/46 G06F 15/16 G06F 12/08 G06F 12/12

Claims (5)

(57) [Claims] 1. A parallel processing system for simultaneously accessing a shared file via the shared buffer from each host, over the shared buffer, the reference buffer and update buffers for page update for the page reference is provided, on the reference buffer Inconsistent between pages for each page
Of the page used to access the new data
Version information and simultaneous updates to the same page
Updater information indicating the updater to be used for
A reference indicating the number of viewers to use to free the buffer
When setting page number information and updating a page, creating a new version of the page in the update buffer without updating the existing page in the reference buffer enables simultaneous execution of page reference and page update. Shared file access means, and when the page is other than the current page, the number of referring persons becomes “0”.
When the reference buffer is released, the current page
In the case of, the number of viewers is “0” and is the same as the current page.
Only if there is no old version page
A file access control method for a parallel processing system, which releases a reference buffer . 2. A method according to claim 1, wherein said shared file access means, when referring to a page, sets a required page to said reference buffer.
And if the referrer is referring to the reference buffer,
Refer to the reference buffer of the
If the required page does not exist
If the reference buffer is allocated to the shared buffer,
Page input processing for inputting required pages from shared files
Section and when the page is updated, the updater updates the page.
If the update buffer is updatable while it is new,
Is an error if the update is in progress, and the above
Copy the corresponding page from the reference buffer to the update buffer.
Page to make the update buffer updatable
The processing device according to claim 1, further comprising a processing unit.
File access control method for the column processing system. 3. The shared file access means, during a commit process, updates an update buffer being updated by itself.
Output to shared file, current page of reference buffer
As the updater
Processing to set the status to none and subtract "1" from the number of viewers
And the update buffer that is updating itself during error processing
Discard and set the reference buffer to no updater status
And if you are updating or referencing,
Perform processing to subtract “1” from the number of viewers in the buffer.
And an error processing unit.
File access system of the parallel processing system according to claim 2
Control method. 4. The image processing apparatus according to claim 1, wherein the page input processing unit includes a reference buffer.
Of the page entered from the shared file
If the version matches the version of the required page,
"1" is added to the number of viewers of the page, and the version is
If they do not match, an error will occur, and the same buffer as the required
If the page exists, the version of the page matches
If you do, add “1” to the number of visitors to the page and
If the versions do not match, the shared buffer
File and enter the required page from the shared file.
3. The parallel processing system according to claim 2, wherein
System file access control method. 5. A shared buffer from each host via a shared buffer.
In the parallel processing system for simultaneously accessing files, a reference buffer for page reference is provided on the shared buffer.
An update buffer for updating the page is provided, and for each page on the reference buffer, a bar of the corresponding page is provided.
Version information, updater information, and referrer count information.
Set and update the page if the existing page in the reference buffer
Update new version page without updating buffer
By creating on the top, the same as page reference and page update
With shared file access means to the time capable of performing, the shared file access means, at the time of commit processing, the update buffers themselves Updating
Output to shared file, current page of reference buffer
As the updater
Processing to set the status to none and subtract "1" from the number of viewers
And the update buffer that is updating itself during error processing
Discard and set the reference buffer to no updater status
And if you are updating or referencing,
Perform processing to subtract “1” from the number of viewers in the buffer.
Parallel processing system, comprising:
System file access control method.