Transfer of event logs for replication of executing programs

• US 8,984,513 B2
• Filed: 03/30/2007
• Issued: 03/17/2015
• 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.
• Primary Examiner(s): Sough, H S
• Assistant Examiner(s): Onat, Umut
• Application Number:
  US12/438,744
• Publication Number:
  US 20090328044A1
• Time in Patent Office: 2,909 Days
• Field of Search: None
• 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 a program executing on the computer system at a destination accessible from the computer system, the method comprising:

receiving an executing program request associated with an executing program;

responsive to the executing program request being a non-deterministic event, blocking the executing program request;

responsive to determining the executing program request is an input for the executing program to be replicated, logging the non-deterministic event in a first storage, delivering the non-deterministic event to the executing program, and unblocking the executing program request;

responsive to determining the executing program request is a non-abortable output request from the executing program for sending an output message, transferring contents of the first storage to the destination, and responsive to an acknowledgment being received from the destination, unblocking the executing program request; and

responsive to expiration of a timer that is reset at each occurrence of a subsequent non-abortable output request, 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 the non-deterministic event being the input for the executing program 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 the nondeterministic event being the non-abortable output request, writing the output message 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 output message from the second storage.

4. The method of claim 3, further comprising:

responsive to 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.

5. The method of claim 3, further comprising:

responsive to the second storage not being full, writing the output message to the second storage and unblocking the executing program request; and

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

6. The method of claim 3, wherein the second storage comprises a cache memory.

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

8. A computer program product comprising a computer memory having a computer readable program stored thereon, wherein the computer readable program, when executed on a computing device, causes the computing device to:

receive an executing program request associated with an executing program;

responsive to the executing program request being a non-deterministic event, block the executing program request;

responsive to determining the executing program request being an input for the executing program to be replicated, log the non-deterministic event in a first storage, deliver the non-deterministic event to the executing program, and unblock the executing program request;

responsive to determining the executing program request is a non-abortable output request from the executing program for sending an output message, transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, unblock the executing program request; and

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

9. The computer program product of claim 8, wherein the computer readable program further causes the computing device to:

responsive to the non-deterministic event being the input for the executing program 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.

10. The computer program product of claim 8, wherein the computer readable program further causes the computing device to;

responsive to the non-deterministic event being the non-abortable output request, write the output message 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 output message from the second storage.

11. The computer program product of claim 10, wherein the computer readable program further causes the computing device to:

responsive to 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.

12. The computer program product of claim 10, wherein the computer readable program further causes the computing device to:

responsive to the second storage not being full, write the output message to the second storage and unblock the executing program request; and

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

13. 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;

receive an executing program request associated with an executing program;

responsive to the executing program request being a non-deterministic event, block the executing program request;

responsive to determining the executing program request is an input for the executing program to be replicated, log the non-deterministic event in a first storage, deliver the non-deterministic event to the executing program, and unblock the executing program request;

responsive to determining the executing program request is a non-abortable output request from the executing program for sending an output message, transfer contents of the first storage to the destination and responsive to an acknowledgment being received from the destination, unblock the executing program request; and

responsive to expiration of a timer reset at each occurrence of a subsequent non-abortable output request, 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 apparatus of claim 13, wherein the instructions further causes the processor to:

responsive to the non-deterministic event being the input for the executing program 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.

15. The apparatus of claim 13, wherein the instructions further causes the processor to:

responsive to the nondeterministic event being the non-abortable output request, write the output message 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 output message from the second storage.

16. The apparatus of claim 15, wherein the instructions further causes the processor to:

responsive to 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 apparatus of claim 15, wherein the instructions further causes the processor to:

responsive to the second storage not being full, write the output message to the second storage and unblock the executing program request; and

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