Shared closures on demand

• US 20080270709A1
• Filed: 04/26/2007
• Published: 10/30/2008
• Est. Priority Date: 04/26/2007
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Smits, Thomas, Schmidt, Oliver Patrick, Kuck, Norbert, Dostert, Jan Boris
• Granted Patent: US 8,046,540 B2
• Time in Patent Office: Days
• US Class Current: 711/147
• CPC Class Codes: G06F 11/1438 Restarting or rejuvenating
• CPC Class Codes: G06F 11/1484 involving virtual machines
• CPC Class Codes: G06F 9/544 Buffers; Shared memory; Pipes

Abstract

A method and apparatus for copying data from a virtual machine to a shared closure on demand. This process improves system efficiency by avoiding the copying of data in the large number of cases where the same virtual machine is the next to request access and use of the data. Load balancing and failure recovery are supported by copying the data to the shared closure when the data is requested by another virtual machine or recovering the data from the failed virtual machine and storing it in the shared closure before a terminated virtual machine is discarded.

Claims

1. A method comprising:

monitoring session data including a session object of a first virtual machine; and

storing an indicator of a location of the first virtual machine and the session object within the first virtual machine in a shared memory location.

2. The method of claim 1, further comprising:

retrieving session data from the first virtual machine at the location.

3. The method of claim 2, wherein the session data is retrieved from the first virtual machine after the first virtual machine has terminated.

4. The method of claim 2, wherein the session data is retrieved in response to a request from a second virtual machine.

5. The method of claim 1, further comprising:

storing retrieved data in the shared memory.

6. The method of claim 1, further comprising:

updating the indicator in response to a session dialogue action.

7. The method of claim 5, wherein retrieved data is stored as a shared closure in the shared memory.

8. The method of claim 1, further comprising:

maintaining the first virtual machine data after termination of the first virtual machine to retrieve data from the location.

9. The method of claim 1, further comprising:

checking for the indicator upon detection of termination of the first virtual machine.

10. The method of claim 1, further comprising:

checking data at the location for coherency.

11. A system comprising:

a shared memory component;

a first virtual machine to service an application server; and

a session manager to store an indicator of session data location within the first virtual machine, the indicator stored in the shared memory component.

12. The system of claim 11, wherein the session manager copies the session data at the location in response to a request from a second virtual machine.

13. The system of claim 11, further comprising:

a server component to retrieve data from the first virtual machine in response to detection of termination of the first virtual machine.

14. The system of claim 11, further comprising:

a session data tracking component to store the indicator.

15. A machine readable medium having instructions stored therein, which if executed by a machine, cause the machine to perform a set of operations comprising:

tracking session activity of a first virtual machine; and

updating a set of references to data in a shared memory in response to session activity, the set of references indicating a location of session data in the first virtual machine.

16. The machine readable medium of claim 15, having further instructions stored therein, which if executed by a machine, cause the machine to perform a set of further operations comprising:

copying session data from the first virtual machine to a shared memory location in response to a request from a second virtual machine.

17. The machine readable medium of claim 15, having further instructions stored therein, which if executed by a machine, cause the machine to perform a set of further operations comprising:

retrieving session data from the first virtual machine after detection of a failure of the first virtual machine.

18. The machine readable medium of claim 16, wherein the session data is stored in shared memory as a shared closure.

19. The machine readable medium of claim 15, having further instructions stored therein, which if executed by a machine, cause the machine to perform a set of further operations comprising:

error checking session data at the location if the first virtual machine failed.

20. The machine readable medium of claim 15, having further instructions stored therein, which if executed by a machine, cause the machine to perform a set of further operations comprising:

maintaining a heap of the first virtual machine after failure until heap data is retrieved.

21. The machine readable medium of claim 15, having further instructions stored therein, which if executed by a machine, cause the machine to perform a set of further operations comprising:

searching shared memory for the set of references corresponding to the first virtual machine to determining support for on demand shared closures for the first virtual machine.

22. The machine readable medium of claim 21, having further instructions stored therein, which if executed by a machine, cause the machine to perform a set of further operations comprising:

updating the set of references in response to a session dialogue action.