Transfer of Event Logs for Replication of Executing Programs

• US 20090328044A1
• Filed: 03/30/2007
• Published: 12/31/2009
• Est. Priority Date: 08/28/2006
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Bergheaud, Philippe, Subhraveti, Dinesh K., Vertes, Marc P.
• Granted Patent: US 8,984,513 B2
• Time in Patent Office: Days
• US Class Current: 718/101
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component
• CPC Class Codes: G06F 11/2048 where the redundant components share neither address space nor persistent storage
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups

Abstract

A mechanism for replicating programs executing on a computer system having a first storage means is provided. The mechanism identifies the events corresponding to requests from one executing program, which may be different from the executing program to be replicated, which are non-deterministic and identifies the ‘Non Abortable Events’ (NAE'"'"'s), which change irremediably the state of the external world that need to be reproduced in the replay of the programs. These events are immediately transferred for replay and the executing program is blocked until the transfer is acknowledged. For the other non-deterministic events, they are logged and sent to the executing program, the executing programs remaining blocked only if the log is full and/or if a timer between two NAEs expires, in this case a log transfer to the standby machine is performed to prepare replication before unblocking of the executing program.

Claims

1. A method executing on a computer system for replicating program executing on the computer system having a first storage, one destination being accessible from the computer system, the method comprising:

responsive to a non deterministic non-deterministic event, blocking an executing program request from an executing program corresponding to that event;

determining whether the non-deterministic event corresponds to a message that is an input for the executing program to be replicated or to an output request from the executing program for sending an output message, wherein the non-deterministic event is a non-abortable event;

responsive to a non-abortable event not occurring, logging the event in the first storage, delivering the event to the executing program to be replicated, and unblocking the executing program request; and

responsive to a non-abortable event, transferring contents of the first storage to the destination, and responsive to an acknowledgment being received from the destination, unblocking the executing program request.

2. The method of claim 1, further comprising:

responsive to a non-abortable event and the first storage being full, transferring contents of the first storage to the destination, and responsive to an acknowledgment being received from the destination, unblocking the executing program request.

3. The method of claim 1 further comprising:

responsive to expiration of a timer, reset at each occurrence of a non-abortable event, transferring contents of the first storage to the destination, and responsive to an acknowledgment being received from the destination, unblocking the executing program request.

4. The method of claim 1 further comprising:

responsive to a non-abortable event, writing the non-abortable event to a second storage and performing the following;

unblocking the executing program request and, in parallel,

transferring contents of the first storage to the destination, and responsive to an acknowledgment

being received from the destination, performing the executing program request, and removing the non-abortable event from the second storage.

5. The method of claim 4, further comprising:

responsive to a non-abortable event and the second storage being full, re-testing whether the second storage is full until a removing step is executed and the second storage is no longer full.

6. The method of claim 4 further comprising:

responsive to a non-abortable event and the second storage not being full, writing the non-abortable event to the second storage, and unblocking the executing program request; and

responsive to a non-abortable event and the second storage being full, for all non-abortable events in the second storage and the last non-abortable event, transferring contents of the first storage up to the last non-abortable event to the destination, and responsive to an acknowledgment being received, performing the request and removing the non-abortable event from the second storage.

7. The method of claim 1, wherein the first storage comprises a first-in-first-out buffer.

8. The method of claim 4, wherein the second storage in comprises a cache memory.

9-11. -11. (canceled)

12. A computer program product comprising a computer recordable medium having a computer readable program recorded thereon, wherein the computer readable program, when executed on a computing device, causes the computing device to:

responsive to a non-deterministic event, block an executing program request from an executing program corresponding to that event;

determine whether the non-deterministic event corresponds to a message that is an input for the executing program to be replicated or to an output request from the executing program for sending an output message, wherein the non-deterministic event is a non-abortable event;

responsive to a non-abortable event not occurring, log the event in the first storage, deliver the event to the executing program to be replicated, and unblock the executing program request; and

responsive to a non-abortable event, transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, unblock the executing program request.

13. The computer program product of claim 12, wherein the computer readable program further causes the computing device to:

responsive to a non-abortable event and the first storage being full, transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, unblock the executing program request.

14. The computer program product of claim 12, wherein the computer readable program further causes the computing device to:

responsive to expiration of a timer, reset at each occurrence of a non-abortable event, transfer contents of the first storage to the destination, and responsive to an acknowledgment being received from the destination, unblock the executing program request.

15. The computer program product of claim 12, wherein the computer readable program further causes the computing device to:

responsive to a non-abortable event, write the non-abortable event to a second storage and performing the following;

unblock the executing program request and, in parallel,

transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, perform the executing program request, and remove the non-abortable event from the second storage.

16. The computer program product of claim 15, wherein the computer readable program further causes the computing device to:

responsive to a non-abortable event and the second storage being full, re-test whether the second storage is full until a removing step is executed and the second storage is no longer full.

17. The computer program product of claim 15, wherein the computer readable program further causes the computing device to:

responsive to a non-abortable event and the second storage not being full, write the non-abortable event to the second storage and unblock the executing program request; and

responsive to a non-abortable event and the second storage being full, for all non-abortable events in the second storage and the last non-abortable event, transfer contents of the first storage up to the last non-abortable event to the destination, and responsive to an acknowledgment being received from the destination, perform the request and remove the non-abortable event from the second storage.

18. An apparatus, comprising:

a processor; and

a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to;

responsive to a non-deterministic event, block an executing program request from an executing program corresponding to that event;

determine whether the non-deterministic event corresponds to a message that is an input for the executing program to be replicated or to an output request from the executing program for sending an output message, wherein the non-deterministic event is a non-abortable event;

responsive to a non-abortable event not occurring, log the event in the first storage, deliver the event to the executing program to be replicated, and unblock the executing program request; and

responsive to a non-abortable event, transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, unblock the executing program request.

19. The apparatus of claim 18, wherein the instructions further causes the processor to:

responsive to a non-abortable event and the first storage being full, transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, unblock the executing program request.

20. The apparatus of claim 18, wherein the instructions further causes the processor to:

responsive to expiration of a timer, reset at each occurrence of a non-abortable event, transfer contents of the first storage to the destination, and responsive to an acknowledgment being received from the destination, unblock the executing program request.

21. The apparatus of claim 18, wherein the instructions further causes the processor to:

responsive to a non-abortable event, write the non-abortable event to a second storage and performing the following;

unblock the executing program request and, in parallel,

transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, perform the executing program request, and remove the non-abortable event from the second storage.

22. The apparatus of claim 21, wherein the instructions further causes the processor to:

responsive to a non-abortable event and the second storage being full, re-test whether the second storage is full until a removing step is executed and the second storage is no longer full.

23. The apparatus of claim 21, wherein the instructions further causes the processor to:

responsive to a non-abortable event and the second storage not being full, write the non-abortable event to the second storage and unblock the executing program request; and

responsive to a non-abortable event and the second storage being full, for all non-abortable events in the second storage and the last non-abortable event, transfer contents of the first storage up to the last non-abortable event to the destination, and responsive to an acknowledgment being received from the destination, perform the request and remove the non-abortable event from the second storage.