Mirror queue in a shared queue environment

• US 20040225721A1
• Filed: 03/29/2002
• Published: 11/11/2004
• Est. Priority Date: 03/29/2002
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wilcock, Glenn Randle, Le, Cuong Minh
• Granted Patent: US 7,464,138 B2
• Time in Patent Office: Days
• US Class Current: 709/213
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A queue management system and a method of managing a queue. This system and method are for use with a parallel processing system including a plurality of clients and a plurality of processors. The clients receive messages and transmit the messages to a shared queue for storage, and the processors retrieve messages from the shared queue and process said messages. The queue management system includes a mirror queue for maintaining a copy of each message transmitted to the shared queue by one of the clients; and means, running on said one of the clients, for storing to the mirror queue, a copy of each message transmitted to the shared queue by said one of the clients. The mirror queue provides the system with continuity in case of an outage of the shared queue. In the event of such an outage, each instance of an application can simply discontinue using the shared queue and process requests from the mirror queue. The mirror queue is used until the shared queue is once again available. Preferably, the copy of each message transmitted to the mirror queue is provided with a reference, such as a pointer, to the location of the message on the shared queue. When a client receives a request for a particular message, the client is able to search its mirror queue for the copy of the message. Also, if necessary, the client, after finding the copy on the mirror queue, is able to use the reference in that copy to find the message on the shared queue.

Claims

1. A queue management system for use on a parallel processing system including a plurality of clients and a plurality of processors, wherein the clients transmit messages for storage on a shared queue, and the processors retrieve messages from the shared queue and process the messages, the queue management system comprising:

a mirror queue on one of the clients for maintaining copies of messages transmitted to the shared queue by said one of the clients; and

means, running on said one of the clients, for storing to the mirror queue, a copy of each message transmitted to the shared queue by said one of the clients.

2. A queue management system according to claim 1, wherein the means for storing to the mirror queue includes means for providing the copy of each message storing to the mirror queue with a reference to the location of the message on the shared queue.

3. A queue management system according to claim 2, wherein said reference is a pointer to the location of the message in the shared queue.

4. A queue management system according to claim 2, wherein said one of the clients further includes means to receive a request for a particular message, and the queue management system further includes means, acting in response to the receipt by said one of the clients, to search the mirror queue for a copy of the particular message.

5. A queue management system according to claim 4, wherein said means to search the mirror queue includes means, acting after the copy of the particular message is found, to use the reference in said copy to locate the message in the shared queue.

6. A method of managing a queue for use with a parallel processing system including a plurality of clients and a plurality of processors, wherein the clients transmit messages for storage on a shared queue, and the processors retrieve messages from the shared queue and process said messages, the method comprising:

maintaining a mirror queue for storing copies of messages transmitted to the shared queue by one of the clients; and

storing to the mirror queue, a copy of each message transmitted to the shared queue by said one of the clients.

7. A method according to claim 6, further comprising the step of, said one of the clients processing messages from the mirror queue in case messages are not available from the shared queue.

8. A method according to claim 6, wherein the storing step includes the step of providing the copy of each message transmitted to the mirror queue with a reference to the location of the message on the shared queue.

9. A method according to claim 8, wherein said reference is a pointer to the location of the message in the shared queue.

10. A method according to claim 8, wherein each of said clients further includes a routine to receive a request for a particular message, and the method includes the further step of searching the mirror queue for a copy of the particular message in response to the receipt by one of the clients of the request for the particular message.

11. A method according to claim 10, wherein said searching step includes the step of, after the copy of the particular message is found, using the reference in said copy to locate the message in the shared queue.

12. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for managing a queue, for use with a parallel processing system including a plurality of clients and a plurality of processors, wherein the clients transmitting messages for storage on a shared queue, and the processors retrieve messages from the shared queue and process said messages, the method steps comprising:

maintaining a mirror queue for storing copies of message transmitted to the shared queue by one of the clients; and

storing to the mirror queue, a copy of each message transmitted to the shared queue by said one of the clients.

13. A program storage device according to claim 12, wherein said method steps further comprise the step of, said one of the clients processing messages from the mirror queue in case messages are not available from the shared queue.

14. A program storage device according to claim 12, wherein the storing step includes the step of providing the copy of each message transmitted to the mirror queue with a reference to the location of the message on the shared queue.

15. A program storage device according to claim 14, wherein said reference is a pointer to the location of the message in the shared queue.

16. A program storage device according to claim 14, wherein each of said clients further includes a routine to receive a request for a particular message, and the method includes the further step of searching the mirror queue for a copy of the particular message in response to the receipt by one of the clients of the request for the particular message.

17. A program storage device according to claim 16, wherein said searching step includes the step of, after the copy of the particular message is found, using the reference in said copy to locate the message in the shared queue.

18. A parallel processing system comprising:

a plurality of clients for receiving messages and transmitting the messages for storage on a shared queue;

a plurality of processors for retrieving messages from the shared queue and processing said messages;

each of said clients including

i) means for maintaining a mirror queue for holding copies of messages transmitted to the shared queue by the client, and

ii) means for storing to the mirror queue, a copy of each message transmitted to the shared queue by said one of the processors.

19. A parallel processing system according to claim 18, wherein:

the storing means includes means for providing the copy of each message transmitted to the mirror queue with a reference to the location of the message on the shared queue; and

each of said clients further includes means, acting in response to the receipt by the client of a particular message, to search the mirror queue for a copy of the particular message, and, after the copy of the particular message is found, to use the reference in said copy to locate the message in the shared queue.