Method and apparatus for providing serialization support for a computer system

• US 6,665,814 B2
• Filed: 11/29/2000
• Issued: 12/16/2003
• Est. Priority Date: 11/29/2000
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Warnes, James Henry, OʼDowd, Anthony John, Kettley, Paul, Hobson, Stephen James, Siddall, Peter
• Primary Examiner(s): Baderman, Scott
• Assistant Examiner(s): Wilson, Yolanda L
• Application Number:
  US09/725,578
• Publication Number:
  US 20020066051A1
• Time in Patent Office: 1,112 Days
• Field of Search: 714/15, 714/16, 714/17, 709/313, 709/314, 709/105, 709/104, 709/102, 709/226
• US Class Current: 714/16
• CPC Class Codes: G06F 11/1474 in transactions G06F16/20 takes precedence
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: G06F 9/466 Transaction processing

Abstract

Provided are a method and apparatus for providing serialization support for computer systems and computer system resources, in particular for application programs which require sequencing and/or consistency of data. The computer system resource includes serialized processes with units of work. A serialization token is provided at the start of a serialized process including at least one unit of work. The serialization token remains in force until the or all of the units of work of the process have been committed or rolled back. The serialization token controls the commencement of other processes of the computer system during the time that it is in force. The serialization is carried out by storing an abstract representation of the process to be serialized in storage which is accessible by all the programs and computers where the serialization applies. In this way, if a process fails, the serialization token remains in force until the process has recovered and has committed or rolled back the units of work in the process. The serialization token can allow only a single thread process or, alternatively, the serialization token can allow a multiple thread process in which the threads have the same serialization token which allows for multiple users.

Claims

1. A method for providing serialization support for a computer system resource which includes processes requiring serialization, the method including:

commencing one of the processes requiring serialization;

creating a representation of the process, the representation including a serialization token for the process;

providing the representation on a medium accessible by all components of the computer system to which the serialization requirement applies;

deleting the representation when the process is complete;

on commencement of a further one of the processes requiring serialization, checking for the existence of the representation on said accessible medium and, if said representation check is positive, controlling serialization of said processes with reference to the serialization token.

2. A method as claimed in claim 1, wherein the serialization token has a locking protocol mapping to the representation.

3. A method as claimed in claim 1, wherein a serialization token for a process prevents other processes commencing during the time between the representation being provided on said medium and the representation being deleted.

4. A method as claimed in claim 1, wherein a serialization token for a process allows other processes having the same serialization token to commence before the step of deleting the representation.

5. A method as claimed in claim 1, wherein the representation includes at least one entry, each entry representing an element of the process, wherein each element can be performed independently.

6. A method as claimed in claim 5, wherein each entry is created, modified and deleted as the element is processed.

7. A method as claimed in claim 5, wherein, in the event of a failure during a process, the locking protocol is persistent until recovery across all the elements of the representation is complete.

8. A method as claimed in claim 5, wherein, in the event of a failure during a process, each element of the process is recovered to a consistent state and the corresponding entry in the representation is then deleted, the representation persisting until the last entry is deleted.

9. A method as claimed in claim 5, wherein each element of the representation can be performed and recovered in parallel with the other elements.

10. A method as claimed in claim 1, wherein the serialized processes run on a plurality of subsystems which share a storage space, and the representation is provided in the shared storage space.

11. A method as claimed in claim 10, wherein the shared storage space is one of a shared database, a shared file system or a coupling means between the subsystems.

12. A method as claimed in claim 10, wherein the computer system includes one or more queue manager programs and the serialized processes are message communication processes for communications between application programs connected to the queue manager programs, each process including at least one unit of work.

13. A method as claimed in claim 12, wherein the computer system uses an application programming interface to indicate to the queue manager programs the commencement of a process with a serialization token.

14. A method as claimed in claim 12, wherein the elements of the process represented by entries in the representation include threads of a process, units of work and individual queues on which units of work act.

15. A method as claimed in claim 14, wherein an entry for a unit of work is deleted when the unit of work is rolled forward or back for each queue that it acts on.

16. A method as claimed in claim 12, wherein the computer system is a plurality of subsystems each with a queue manager, the subsystems coupled together by a coupling means which has shared storage space on which the representation is stored in the form of a list structure.

17. A method as claimed in claim 16, wherein, in the event of a failure during a process, other queue managers can access the shared storage space to recover the elements of the process independently and in parallel.

18. A computer system having serialization support, the computer system comprising:

one or more components on which processes requiring serialization are run;

a medium, accessible by the one or more components, on which a representation of an active process is created during running of the process, and from which the representation is deleted when the process is complete;

means for creating the representation during running of a process and for deleting the representation when the process is complete; and

means responsive to commencement of a further process requiring serialization for checking for the existence of the representation on said medium and, if said check is positive, for controlling serialization of said active process and said further process.

19. A computer system according to claim 18, wherein each process requiring serialization has a respective serialization token associated therewith and the serialization of said active process and said further process is performed with reference to said serialization token.

20. A computer system as claimed in claim 19, wherein the serialization token has a locking protocol mapping to the representation.

21. A computer system as claimed in claim 19, wherein a serialization token for a process prevents other processes commencing during the time that it is in force.

22. A computer system as claimed in claim 19, wherein a serialization token for a process allows other processes to commence if the serialization token allows for multiple processes.

23. A computer system as claimed in claim 18, wherein the representation includes at least one entry, each entry representing an element of the process, wherein each element can be performed independently.

24. A computer system as claimed in claim 23, wherein each entry is created, modified and deleted as the element is processed.

25. A computer system as claimed in claim 23, wherein each process requiring serialization has a respective serialization token associated therewith and the serialization of said active process and said further process is performed with reference to said serialization token, the serialization token having a locking protocol mapping to the representation, and wherein, in the event of a failure during a process, the locking protocol is persistent until recovery across all the elements of the representation is complete.

26. A computer system as claimed in claim 23, wherein, in the event of a failure during a process, each element of the process is recovered to a consistent state and the corresponding entry in the representation is then deleted, the representation persisting until the last entry is deleted.

27. A computer system as claimed in claim 23, wherein each element of the representation is capable of being performed and recovered in parallel with the other elements.

28. A computer system as claimed in claim 18, wherein the components of the computer system are a plurality of subsystems which share a storage space, and the representation is provided in the shared storage space.

29. A computer system as claimed in claim 28, wherein the shared storage space is one of a shared database, a shared file system or a coupling means between the subsystems.

30. A computer system as claimed in claim 28, wherein the subsystems are one or more queue manager programs and the serialized processes are message communication processes from application programs connected to the queue managers, each process including at least one unit of work.

31. A computer system as claimed in claim 30, wherein each process requiring serialization has a respective serialization token associated therewith and the serialization of said active process and said further process is performed with reference to said serialization token, and wherein the computer system uses an application programming interface to indicate to the queue manager programs the commencement of a process with a serialization token.

32. A computer system as claimed in claim 30, wherein the elements of the process represented by entries in the representation includes threads of a process, units of work and individual queues on which units of work act.

33. A computer system as claimed in claim 32, wherein an entry for a unit of work is deleted when the unit of work is rolled forward or back for each queue that it acts on.

34. A computer system as claimed in claim 30, wherein the computer system is a plurality of subsystems each with a queue manager, the subsystems coupled together by a coupling means which has shared storage space on which the representation is stored in the form of a list structure.

35. A computer system as claimed in claim 34, wherein, in the event of a failure during a process, other queue managers can access the shared storage space to recover the elements of the process independently and in parallel.

36. A method for providing serialization support for a computer system comprising a plurality of subsystems with a shared memory space, the subsystems having a plurality of processes, wherein a process is allocated a serialization token which has a locking protocol mapping to a list structure representing the process in the shared memory space, the locking protocol enabling the plurality of processes to serialize with each other.

37. A computer program product stored on a computer readable storage medium, comprising computer readable program code means for performing the steps of a method for serializing processes, the method including:

commencing one of a set of processes requiring serialization;

creating a representation of the process, the representation including a serialization token for the process;

providing the representation on a medium accessible by all components of the computer system to which the serialization requirement applies;

deleting the representation when the process is complete;

on commencement of a further one of the processes requiring serialization, checking for the existence of the representation on said accessible medium and, if said representation check is positive, controlling serialization of said processes with reference to said serialization token.

38. A method for providing serialization support for a computer system resource which includes processes requiring serialization, the method including:

commencing one of the processes requiring serialization;

creating a representation of the process and providing the representation on a medium accessible by all components of the computer system to which the serialization requirement applies;

deleting the representation when the process is complete;

on commencement of a further one of the processes requiring serialization, checking for the existence of the representation on said accessible medium and, if said representation check is positive, controlling serialization of said processes.