Method and apparatus for suspending a software virtual machine

• US 20030033344A1
• Filed: 08/06/2002
• Published: 02/13/2003
• Est. Priority Date: 08/06/2001
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Abbott, Paul Harry, Chapman, Matthew Paul
• Granted Patent: US 7,191,441 B2
• Time in Patent Office: Days
• US Class Current: 718/1
• CPC Class Codes: G06F 9/4493 Object persistence
• CPC Class Codes: G06F 9/4843 by program, e.g. task dispatcher, supervisor, operating system
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A computer system includes a software virtual machine (such as Java) for running one or more applications. An object is provided that is responsive to a call from an application for placing the virtual machine and application into a state of suspension. This involves interrupting all current threads, and recording the state of the components of the virtual machine, including heap, threads, and stack, into a serialization data structure. Subsequently the serialization data structure can be invoked to resume the virtual machine and application from the state of suspension. Note that many virtual machines can be cloned from the single stored data structure. One benefit of this approach is that a new virtual machine can effectively be created in an already initialized state.

Claims

1. A method of saving in suspended form an application running on a software virtual machine on a computer system, comprising the steps of:

receiving a call from an application for placing the virtual machine and application into a state of suspension;

determining the current state of the components of the virtual machine, including heap, threads, and stack; and

storing the determined state into a save file.

2. The method of claim 1, further comprising the step of abandoning creation of the save file if there are any pinned objects on the heap.

3. The method of claim 1, further comprising the step of forcing the compilation of at least some of said application prior to determining the current state of the components of the virtual machine.

4. The method of claim 1, further comprising the step of performing a garbage collection on the heap immediately prior to determining the current state of the components of the virtual machine.

5. The method of claim 1, further comprising the step of replacing absolute references on the heap by relative references before storing the save file.

6. The method of claim 5, further comprising the step of creating a linked list of the relative references for each object.

7. The method of claim 5, further comprising the step, responsive to said call, of stopping the current thread and initiating a new thread specifically to perform the save operation.

8. The method of claim 5, further comprising the step of replacing absolute references by symbolic references for code references from the stack.

9. The method of claim 5, wherein at least a partial initialisation of the application is performed prior to the call from the application to place the virtual machine and application into a state of suspension.

10. The method of claim 5, further comprising the step of interacting with various subsystems of the virtual machine to obtain from them state information to be recorded in the save file.

11. The method of claim 5, further comprising the step of continuing with execution of the application, once the save file has been stored.

12. The method of claim 5, further comprising the step of restoring the suspended application running on the software virtual machine on the computer system.

13. The method of claim 12, wherein the step of restoring includes recreating the components of the virtual machine, including heap, threads, and stack, before restarting the application.

14. A method of restoring a suspended application running on a software virtual machine (VM) on a computer system from a save file, comprising the steps of:

retrieving a save file;

recreating the components of the virtual machine, including heap, threads, and stack, from data in the save file; and

restarting application

15. The method of claim 14, wherein the application is restored multiple times from the same save file.

16. A save tool for storing the suspended state of an application running on a software virtual machine on a computer system, said save tool comprising:

means for receiving a call from an application for placing the virtual machine and application into a state of suspension;

means for determining the current state of the components of the virtual machine, including heap, threads, and stack; and

means for storing the determined state into a save file.

17. The save tool of claim 16, further comprising means for abandoning creation of the save file if there are any pinned objects on the heap.

18. The save tool of claim 16, further comprising means for forcing the compilation of at least some of said application prior to determining the current state of the components of the virtual machine.

19. The save tool of claim 16, further comprising means for performing a garbage collection on the heap immediately prior to determining the current state of the components of the virtual machine.

20. The save tool of claim 16, further comprising means for replacing absolute references on the heap by relative references before storing the save file.

21. The save tool of claim 20, further comprising means for creating a linked list of the relative references for each object.

22. The save tool of claim 16, further comprising means, responsive to said call, for stopping the current thread and initiating a new thread specifically to perform the save operation.

23. The save tool of claim 16, further comprising means for replacing absolute references by symbolic references for code references from the stack.

24. The save tool of claim 16, wherein at least a partial initialisation of the application is performed prior to the call from the application to place the virtual machine and application into a state of suspension.

25. The save tool of claim 16, further comprising means for interacting with various subsystems of the virtual machine to obtain from them state information to be recorded in the save file.

26. The save tool of claim 16, further comprising means for restoring the suspended application running on the software virtual machine on the computer system.

27. The save tool of claim 26, wherein the means for restoring includes means for recreating the components of the virtual machine, including heap, threads, and stack, before restarting the application.

28. A restore tool for restoring a suspended application running on a software virtual machine (VM) on a computer system from a save file, comprising:

means for retrieving a save file;

means for recreating the components of the virtual machine, including heap, threads, and stack, from data in the save file; and

means for restarting application.

29. The restore tool of claim 28, wherein the application is restored multiple times from the same save file.

30. A computer program product comprising program instructions encoded in machine-readable format on a medium, said instructions when loaded into a computer system allowing an application running on a software virtual machine on the computer system to be saved in a suspended form by implementing the steps of:

receiving a call from an application for placing the virtual machine and application into a state of suspension;

determining the current state of the components of the virtual machine, including heap, threads, and stack; and

storing the determined state into a save file.

31. The computer program product of claim 30, further implementing the step of abandoning creation of the save file if there are any pinned objects on the heap.

32. The computer program product of claim 30, further implementing the step of forcing the compilation of at least some of said application prior to determining the current state of the components of the virtual machine.

33. The computer program product of claim 30, further implementing the step of performing a garbage collection on the heap immediately prior to determining the current state of the components of the virtual machine.

34. The computer program product of claim 30, further implementing the step of replacing absolute references on the heap by relative references before storing the save file.

35. The computer program product of claim 34, further implementing the step of creating a linked list of the relative references for each object.

36. The computer program product of claim 34, further implementing the step, responsive to said call, of stopping the current thread and initiating a new thread specifically to perform the save operation.

37. The computer program product of claim 34, further implementing the step of replacing absolute references by symbolic references for code references from the stack.

38. The computer program product of claim 34, wherein at least a partial initialisation of the application is performed prior to the call from the application to place the virtual machine and application into a state of suspension.

39. The computer program product of claim 34, further implementing the step of interacting with various subsystems of the virtual machine to obtain from them state information to be recorded in the save file.

40. The computer program product of claim 34, further implementing the step of continuing with execution of the application, once the save file has been stored.

41. The computer program product of claim 34, further implementing the step of restoring the suspended application running on the software virtual machine on the computer system.

42. The method of claim 41, wherein the step of restoring includes recreating the components of the virtual machine, including heap, threads, and stack, before restarting the application.

43. A computer program product comprising program instructions encoded in a machine-readable format on a medium, said instructions, when loaded into a computer system, causing it to restore a suspended application running on a software virtual machine (VM) on the computer system from a save file, by performing the steps of:

retrieving a save file;

recreating the components of the virtual machine, including heap, threads, and stack, from data in the save file; and

restarting application.

44. The computer program product of claim 43, wherein the application is restorable multiple times from the same save file.