System and method for managing memory of Java session objects

• US 8,015,561 B2
• Filed: 12/28/2004
• Issued: 09/06/2011
• Est. Priority Date: 12/28/2004
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Stanev, Georgi
• Primary Examiner(s): Puente; Emerson C
• Assistant Examiner(s): Truong; Camquy
• Application Number:
  US11/025,316
• Publication Number:
  US 20060143609A1
• Time in Patent Office: 2,443 Days
• Field of Search: 718/1, 714/13
• US Class Current: 718/1
• CPC Class Codes: G06F 11/1484 involving virtual machines

Abstract

A method for managing a session with a client is described in which the method receives from the client a request for the session. The session is handled with a first virtual machine. The method places the session state information for the session into an object located in the first virtual machine'"'"'s local memory. The method writes into a shared memory an object that contains the session state information. In response to a failure that renders the first virtual machine unable to handle the session, the method reads the object in the shared memory from the shared memory and places it into a second virtual machine'"'"'s local memory. Lastly, the method receives from the client another request for the session, and handles the another request with the second virtual machine and the session state information.

Claims

1. A method for managing a session with a client, comprising:

receiving from said client a request, said request being part of said session, said session handled with a first virtual machine;

placing session state information for said session into an object located in local memory of said first virtual machine, said session state information including a change of a state of said session after a successful handling of said request by said first virtual machine and before a successful handling of an additional request by said first virtual machine said additional request being part of said session;

writing into a shared memory said object, said shared memory shared by said first virtual machine and a second virtual machine, said writing being performed during said session after said successful handling of said request by said first virtual machine and before said successful handling of said additional request by said first virtual machine;

creating a reference from said object in said shared memory to said object in said local memory of said first virtual machine;

in response to a failure that renders said first virtual machine unable to handle said session, reading said object from said shared memory and placing said object into a local memory of said second virtual machine;

receiving from said client said additional request; and

handling said additional request with said second virtual machine based on said object.

2. The method of claim 1 wherein said first and second virtual machines are both Java virtual machines.

3. The method of claim 2 wherein said first virtual machine interprets code for a first Java container and said second virtual machine interprets code for a second Java container.

4. The method of claim 1 wherein said method further comprises placing said object in said local memory of said first virtual machine into a deactivated state before said writing.

5. The method of claim 4 wherein said method further comprises deleting said object in said local memory of said first virtual machine while it is in said deactivated state.

6. The method of claim 1 wherein at least one of said first virtual machine and said second virtual machine is running on a computing system having more virtual machines than processors.

7. The method of claim 1, wherein said object is a member of a shared closure.

8. An article of manufacture including program code which, when executed by a machine, causes the machine to perform a method, the method comprising:

receiving from a client a request, said request being part of a session, said session handled with a first virtual machine;

placing session state information for said session into an object located in local memory of said first virtual machine, said session state information including a change of a state of said session after a successful handling of said request by said first virtual machine and before a successful handling of an additional request by said first virtual machine, said additional request being part of said session;

writing into a shared memory said object, said shared memory shared by said first virtual machine and a second virtual machine, said writing being performed during said session after said successful handling of said request by said first virtual machine and before said successful handling of said additional request by said first virtual machine;

in response to a failure that renders said first virtual machine unable to handle said session, reading said object from said shared memory and placing said object into local memory of said second virtual machine;

receiving from said client said additional request; and

handling said additional request with said second virtual machine based on said object.

9. The article of manufacture of claim 8 wherein said first and second virtual machines are both Java virtual machines.

10. The article of manufacture of claim 9 wherein said first virtual machine interprets code for a first Java container and said second virtual machine interprets code for a second Java container.

11. The article of manufacture of claim 8 wherein said method further comprises placing said object in said local memory of said first virtual machine into a deactivated state before said writing.

12. The article of manufacture of claim 11 wherein said method further comprises deleting said object in said local memory of said first virtual machine while it is in said deactivated state.

13. A method for managing a session with a client, comprising:

receiving from said client a request, said request being part of said session, said session handled with a first virtual machine;

placing session state information for said session into an object located in local memory of said first virtual machine, said session state information including a change of a state of said session after a successful handling of said request by said first virtual machine and before a successful handling of an additional request by said first virtual machine, said additional request being part of said session;

writing into a shared memory said object, said shared memory shared by said first virtual machine and a second virtual machine, said writing being performed during said session after said successful handling of said request by said first virtual machine and before said successful handling of said additional request by said first virtual machine;

creating a reference from said object in said shared memory to said object in said local memory of said first virtual machine;

in response to a failure that renders said first virtual machine unable to handle said session, reading said object from said shared memory and placing said object into a local memory of said second virtual machine; and

receiving from said client said additional request with said second virtual machine based on said object;

handling said additional request with said second virtual machine based on said object.

14. The method of claim 13 wherein said first and second virtual machines are both Java virtual machines.

15. An article of manufacture including program code which, when executed by a machine, causes the machine to perform a method, the method comprising:

receiving from a client a first request, said request being part of said a session, said session handled with a first virtual machine;

placing session state information for said session into an object located in local memory of said virtual machine, said session state information including a change of a state of said session after a successful handling of said request by said first virtual machine and before a successful handling of an additional request by said first virtual machine, said additional request being part of said session;

writing into a shared memory said object, said shared memory shared by said first virtual machine and a second virtual machine, said writing being performed during said session after said successful handling of said request by said first virtual machine and before said successful handling of said additional request by said first virtual machine;

creating a reference from said object in said shared memory to said object in said local memory of said first virtual machine;

in response to a failure that renders said first virtual machine unable to handle said session, reading said object from said shared memory and placing it into a local memory of said second virtual machine;

receiving from said client said additional request; and

handling said additional request with said second virtual machine based on said object.

16. The article of manufacture of claim 15 wherein said first and second virtual machines are both Java virtual machines.