Mechanism for enabling session information to be shared across multiple processes

• US 20050204045A1
• Filed: 04/29/2005
• Published: 09/15/2005
• Est. Priority Date: 09/24/1999
• Status: Active Grant

• Current Assignee: Ruslan Belkin, Viswanath Ramachandran
• Original Assignee: Ruslan Belkin, Viswanath Ramachandran
• Inventors: Belkin, Ruslan, Ramachandran, Viswanath
• Granted Patent: US 8,103,779 B2
• Time in Patent Office: Days
• US Class Current: 709/227
• CPC Class Codes: G06F 2209/5016 Session
• CPC Class Codes: G06F 2209/5018 Thread allocation
• CPC Class Codes: G06F 9/5027 the resource being a machine, e.g. CPUs, Servers, Terminals
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

A mechanism for enabling session information to be shared across multiple processes in a multi-process environment is disclosed. There is provided a shared persistent memory-mapped file in a file system, which is mapped to the memory space of each of the processes. This file is used by all of the processes to store session information. Because the memory space of each process is mapped to the shared file, each process is able to access and manipulate all of the sessions in the system. Thus, sessions are no longer maintained on a process-specific basis. Rather, they are maintained on a centralized, shared basis. As a result, different requests pertaining to the same session may be serviced by different server processes without any adverse effects. Each process will be able to access and manipulate all of the state information pertaining to that session. By enabling session information to be shared, this mechanism eliminates the session management errors experienced by the prior art.

Claims

1. A computer system, comprising:

a shared storage;

a first server process, said first server process servicing a first request pertaining to a particular session, said first server process storing session information pertaining to said particular session in said shared storage; and

a second server process, said second server process servicing a second request pertaining to said particular session, said second server process accessing said session information from said shared storage and using said session information to service said second request.

2. The system of claim 1, wherein said second server process updates said session information to derive a set of updated session information, and wherein said second server process stores said updated session information in said shared storage.

3. The system of claim 2, wherein said updated session information replaces said session information in said shared storage.

4. The system of claim 3, further comprising:

a third server process, said third server process servicing a third request pertaining to said particular session, said third server process accessing said updated session information from said shared storage and using said updated session information to service said third request.

5. The system of claim 1, wherein said shared storage comprises a memory-mapped file.

6. The system of claim 5, wherein each of said first and second server processes has a memory space associated therewith, and wherein said memory-mapped file is mapped to at least a portion of the memory space associated with said first server process and at least a portion of the memory space associated with said second server process.

7. The system of claim 1, wherein said first server process stores said session information into said shared storage in the form of a serialized byte stream.

8. The system of claim 7, wherein said second server process deserializes said serialized byte stream prior to using said session information to service said second request.

9. The system of claim 1, wherein said second server process sets a busy indicator associated with said session information to indicate that said session information is currently in use, thereby preventing any other server process from using said session information while said second server process is using said session information.

10. A computer implemented method for servicing requests, comprising:

instantiating a first server process;

instantiating a second server process;

receiving a first request pertaining to a particular session;

servicing said first request with said first server process, said first server process storing session information pertaining to said particular session in a shared storage;

receiving a second request pertaining to said particular session; and

servicing said second request with said second server process, said second server process accessing said session information from said shared storage and using said session information to service said second request.

11. The method of claim 10, wherein servicing said second request comprises:

updating said session information to derive a set of updated session information; and

storing said updated session information into said shared storage.

12. The method of claim 11, wherein storing said updated session information into said shared storage comprises:

overwriting said session information with said updated session information.

13. The method of claim 12, further comprising:

instantiating a third server process;

receiving a third request pertaining to said particular session; and

servicing said third request with said third server process, said third server process accessing said updated session information from said shared storage and using said updated session information to service said third request.

14. The method of claim 10, wherein said shared storage comprises a memory-mapped file.

15. The method of claim 14, wherein each of said first and second server processes has a memory space associated therewith, and wherein said method further comprises:

mapping at least a portion of the memory space associated with said first server process to said memory-mapped file; and

mapping at least a portion of the memory space associated with said second server process to said memory-mapped file.

16. The method of claim 10, wherein said first server process stores said session information into said shared storage in the form of a serialized byte stream.

17. The method of claim 16, wherein said second server process deserializes said serialized byte stream prior to using said session information to service said second request.

18. The method of claim 10, wherein servicing said second request comprises:

setting a busy indicator associated with said session information to indicate that said session information is currently in use, thereby preventing any other server process from using said session information while said second server process is using said session information.

19. A computer readable medium having stored thereon instructions which, when executed by one or more processors, cause the one or more processors to service requests, said computer readable medium comprising:

instructions for causing one or more processors to instantiate a first server process;

instructions for causing one or more processors to instantiate a second server process;

instructions for causing one or more processors to receive a first request pertaining to a particular session;

instructions for causing one or more processors to service said first request with said first server process, said first server process storing session information pertaining to said particular session in a shared storage;

instructions for causing one or more processors to receive a second request pertaining to said particular session; and

instructions for causing one or more processors to service said second request with said second server process, said second server process accessing said session information from said shared storage and using said session information to service said second request.

20. The computer readable medium of claim 19, wherein the instructions for causing one or more processors to service said second request comprises:

instructions for causing one or more processors to update said session information to derive a set of updated session information; and

instructions for causing one or more processors to store said updated session information into said shared storage.

21. The computer readable medium of claim 20, wherein the instructions for causing one or more processors to store said updated session information into said shared storage comprises:

instructions for causing one or more processors to overwrite said session information with said updated session information.

22. The computer readable medium of claim 21, further comprising:

instructions for causing one or more processors to instantiate a third server process;

instructions for causing one or more processors to receive a third request pertaining to said particular session; and

instructions for causing one or more processors to service said third request with said third server process, said third server process accessing said updated session information from said shared storage and using said updated session information to service said third request.

23. The computer readable medium of claim 19, wherein said shared storage comprises a memory-mapped file.

24. The computer readable medium of claim 23, wherein each of said first and second server processes has a memory space associated therewith, and wherein said computer readable medium further comprises:

instructions for causing one or more processors to map at least a portion of the memory space associated with said first server process to said memory-mapped file; and

instructions for causing one or more processors to map at least a portion of the memory space associated with said second server process to said memory-mapped file.

25. The computer readable medium of claim 19, wherein said first server process stores said session information into said shared storage in the form of a serialized byte stream.

26. The computer readable medium of claim 25, wherein said second server process deserializes said serialized byte stream prior to using said session information to service said second request.

27. The computer readable medium of claim 19, wherein the instructions for causing one or more processors to service said second request comprises:

instructions for causing one or more processors to set a busy indicator associated with said session information to indicate that said session information is currently in use, thereby preventing any other server process from using said session information while said second server process is using said session information.