Methods, apparatus, and product for distributed garbage collection

• US 5,832,529 A
• Filed: 10/11/1996
• Issued: 11/03/1998
• Est. Priority Date: 10/11/1996
• Status: Expired due to Term

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Waldo, James H., Wollrath, Ann M., Riggs, Roger
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): LEWIS, CHERYL RENEA
• Application Number:
  US08/729,421
• Time in Patent Office: 753 Days
• Field of Search: 707/206, 707/201
• US Class Current: 1/1
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 12/0261 using reference counting
• CPC Class Codes: G06F 16/289 Object oriented databases
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers
• CPC Class Codes: G06F 9/465 Distributed object oriented systems remote method invocation [RMI] G06F9/548
• CPC Class Codes: G06F 9/5011 the resources being hardware resources other than CPUs, Servers and Terminals
• CPC Class Codes: G06F 9/5016 the resource being the memory
• CPC Class Codes: G06F 9/5022 Mechanisms to release resources
• CPC Class Codes: G06F 9/5055 considering software capabilities, i.e. software resources associated or available to the machine
• CPC Class Codes: G06F 9/5061 Partitioning or combining of resources
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: G06F 9/547 Remote procedure calls [RPC]; Web services
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing
• CPC Class Codes: H04L 12/433 with asynchronous transmission, e.g. token ring, register insertion
• CPC Class Codes: H04L 69/24 Negotiation of communication capabilities
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 : Recoverability
• CPC Class Codes: Y10S 707/99957 : Garbage collection

Abstract

In accordance with the present invention a process is provided for allocating and deallocating resources in a distributed processing system having a requester platform and a server platform. The process involves receiving a request from the requestor platform referring to a system resource and specifying a requested lease period, permitting shared access to the system resource for a lease period, sending a return call to the requestor platform advising of the lease period, and deallocating the system resource when the lease period expires.

Claims

1. A method for managing resources comprising the steps of:

receiving a request from a process referring to a resource and specifying a requested lease period;

permitting shared access to the resource for a granted lease period;

advising the process of the granted lease period; and

deallocating the resource when the granted lease period expires.

2. The method of claim 1, wherein the permitting step includes the substep of:

determining the granted lease period to be a period less than the requested lease period.

3. The method of claim 1, wherein the permitting step includes the substep of:

determining the granted lease period based on at least one of the requested lease period, a measure of the resource, and other granted lease periods for the resource.

4. The method of claim 1, wherein the permitting step includes the substep of:

allocating the resource upon a determination that it was not previously allocated.

5. The method of claim 1, wherein the permitting step includes the substep of:

incrementing a reference count corresponding to the resource, the reference count indicating how many processes currently have references to the resource.

6. The method of claim 5, further comprising the step of:

receiving a second request from the process indicating that the process wishes to terminate its access to an identified resource; and

decrementing the reference count corresponding to the identified resource.

7. The method of claim 6, wherein the deallocating step includes the substep of:

invoking a garbage collection process to deallocate the identified resource when the reference count indicates no processes currently access the identified resource.

8. The method of claim 1, wherein the deallocating step includes the substep of:

invoking a garbage collection process to reclaim the resource when shared access to the resource is no longer requested.

9. A method for managing resources comprising the steps of:

requesting from a process access to a resource for a lease period;

receiving from the process a granted lease period during which shared access to the resource is permitted; and

sending a request to the process for a new lease period upon a determination that the granted lease period is about to expire but access to the resource has not completed.

10. The method of claim 9, further comprising the step of:

prior to expiration of the granted lease period, sending a different request indicating that shared access to the resource is no longer requested.

11. An apparatus comprising:

a receiving module configured to receive a request from a process referring to a resource and specifying a requested lease period;

a resource allocator configured to permit shared access to the resource for a granted lease period;

an advising module configured to advise the process of the granted lease period; and

a resource deallocator configured to deallocate the resource when the granted lease period expires.

12. The apparatus of claim 11, wherein the resource allocator includes:

a determining module configured to determine the granted lease period to be a period less than the requested lease period.

13. The apparatus of claim 11, wherein the resource allocator includes:

a determining module configured to determine the granted lease period based on at least one of the requested lease period, a measure of the resource, and other granted lease periods for the resource.

14. The apparatus of claim 11, wherein the resource allocator includes:

an allocating module configured to allocate the resource upon a determination that it was not previously allocated.

15. The apparatus of claim 11, wherein the resource allocator includes:

an incrementing module configured to increment a reference count corresponding to the resource, the reference count indicating how many processes currently have references to the resource.

16. The apparatus of claim 15, further comprising:

a second receiving module configured to receive a second request from the process indicating that the process wishes to terminate its access to an identified resource; and

a decrementing module configured to decrement the reference count corresponding to the identified resource.

17. The apparatus of claim 16, wherein the resource deallocator includes:

an invoker configured to invoke a garbage collection process to deallocate the identified resource when the reference count indicates no processes currently access to the identified resource.

18. The apparatus of claim 11, wherein the resource deallocator includes:

an invoker configured to invoke a garbage collection process to reclaim the resource when shared access to the resource is no longer requested.

19. An apparatus comprising:

a requesting module configured to request from a process access to a resource for a lease period;

a receiving module configured to receive from the process a granted lease period during which shared access to the resource is permitted; and

a second sending module configured to send another request to the process for a new lease period upon a determination that the granted lease period is about to expire but access to the resource has not completed.

20. The apparatus of claim 19, further comprising:

a second sending module configured to send a different request indicating that shared access to the resource is no longer requested prior to expiration of the granted lease period.

21. A computer program product comprising:

a computer usable medium having computer readable code embodied therein for managing resources, the computer usable medium comprising;

a receiving module configured to receive a request from a process referring to a resource and specifying a requested lease period;

a resource allocator configured to permit shared access to the resource for a granted lease period;

an advising module configured to advise of the granted lease period; and

a resource deallocator configured to deallocate the resource when the granted lease period expires.

22. The computer program product of claim 21, wherein the resource allocator includes:

a determining module configured to determine the granted lease period to be a period less than the requested lease period.

23. The computer program product of claim 21, wherein the resource allocator includes:

a determining module configured to determine the granted lease period based on at least one of the requested lease period, a measure of the resource, and other granted lease periods for the resource.

24. The computer program product of claim 21, wherein the resource allocator includes:

an allocating module configured to allocate the resource upon a determination that it was not previously allocated.

25. The computer program product of claim 21, wherein the resource allocator includes:

a reference count module configured to indicate a number of processes that currently have references to the resource.

26. The computer program product of claim 25, the computer usable medium further comprising:

a second receiving module configured to receive a second request from the process indicating that the process wishes to terminate its access to an identified resource; and

a decrementing module configured to decrement the reference count corresponding to the identified resource.

27. The computer program product of claim 26, wherein the resource deallocator includes:

an invoker configured to invoke a garbage collection process to deallocate the identified resource when the reference count indicates no processes currently access the identified resource.

28. The computer program product of claim 21, wherein the resource deallocator includes:

an invoker configured to invoke a garbage collection process to reclaim the resource when shared access to the resource is no longer requested.

29. A computer program product comprising:

a computer usable medium having computer readable code embodied therein for managing resources, the computer usable medium comprising;

a requesting module configured to request from a process access to a resource for a lease period;

a receiving module configured to receive from the process a granted lease period during which the process permits shared access to the resource; and

a sending module configured to send another request to the process for a new lease period upon a determination that the granted lease period is about to expire.

30. The computer program product of claim 29, the computer usable medium further comprising:

a second sending module configured to send a different request indicating that shared access to the resource is no longer requested prior to expiration of the granted lease period.

31. A computer system comprising:

a computer processor;

a memory which is operatively coupled to the computer processor; and

a computer process which executes in the computer processor for the memory and which includes;

a receiving module configured to receive a request from a process referring to a resource and specifying a requested lease period;

a resource allocator configured to permit shared access to the resource for a granted lease period;

an advising module configured to advise of the granted lease period; and

a resource deallocator configured to deallocate the resource when the granted lease period expires.

32. The computer system of claim 31, wherein the resource allocator includes:

a determining module configured to determine the granted lease period to be a period less than the requested lease period.

33. The computer system of claim 31, wherein the resource allocator includes:

a determining module configured to determine the granted lease period based on at least one of the requested lease period, a measure of the resource, and other granted lease periods for the resource.

34. The computer system of claim 31, wherein the resource allocator includes:

an allocating module configured to allocate the resource upon a determination that it was not previously allocated.

35. The computer system of claim 31, wherein the resource allocator includes:

a reference count module configured to indicate a number of processes that currently have references to the resource.

36. The computer system of claim 35, wherein the computer process further includes:

a second receiving module configured to receive a second request from the process indicating that the process wishes to terminate its access to an identified resource; and

a decrementing module configured to decrement the reference count corresponding to the identified resource.

37. The computer system of claim 36, wherein the resource deallocator includes:

an invoker configured to invoke a garbage collection process to deallocate the identified resource when the reference count indicates no processes currently access the identified resource.

38. The computer system of claim 31, wherein the resource deallocator includes:

an invoker configured to invoke a garbage collection process to reclaim the resource when shared access to the resource is no longer requested.

39. The method of claim 31, further comprising the steps of;

(e) receiving new requests from the requestor platforms including references to the system resources and indicating that the requestor platforms request to terminate access to the system resources of the new requests; and

(f) decrementing the reference counter corresponding to each of the referenced system resources specified in the new requests.

40. A computer system comprising:

a computer processor;

a memory which is operatively coupled to the computer processor; and

a computer process which executes in the computer processor for the memory and which includes;

a requesting module configured to request from a process access to a resource for a lease period;

a receiving module configured to receive from the process a granted lease period during which the process permits shared access to the resource; and

a sending module configured to send another request to the process for a new lease period upon a determination that the granted lease period is about to expire.

41. The computer system of claim 40, wherein the computer process further includes:

a second sending module configured to send a different request indicating that shared access to the resource is no longer requested prior to expiration of the granted lease period.

42. In a distributed processing system having a plurality of platforms, a method for allocating and deallocating resources distributed among the platforms comprising the steps, performed by server platforms, of:

(a) receiving requests from requestor platforms including references to system resources and requested lease periods, the requests indicating that the corresponding requestor platform seeks access to the referenced system resource for the requested period of time in the request;

(b) allocating each of the referenced system resources by

(i) setting a corresponding grant period in response to each of the requested lease periods, the grant period indicating an interval for which each of the referenced system resources associated with requests will be available for access by the platforms, and

(ii) incrementing a corresponding reference counter, the reference counter indicating a number of the platforms accessing the corresponding system resource as determined by the receipt of requests;

(c) sending responses to the requestor platforms, in response to associated requests, specifying the grant periods for the resources referenced in the associated requests;

(d) initiating a garbage collection process to deallocate each of the referenced system resources when

(i) the grant period for each referenced system resource expires, or

(ii) the corresponding reference counter is a state indicating that no requestor platforms currently seek access to each of the referenced system resources.

43. A method for managing resources comprising the steps of:

receiving a request for a resource and specifying a requested lease period;

permitting access to the resource for a granted lease period based on the requested lease period; and

releasing the resource when the granted lease period expires.

44. The method of claim 43, wherein the permitting step includes the substep of

determining the granted lease period to be a period less than the requested lease period.

45. The method of claim 43, wherein the permitting step includes the substep of

determining the granted lease period based on at least one of the requested lease period, a measure of the resource, and other granted lease periods for the resource.

46. The method of claim 43, wherein the permitting step includes the substep of

designating the resource upon a determination that access to the resource was not previously permitted.

47. The method of claim 43, wherein the permitting step includes the substep of

incrementing a reference count corresponding to the resource, the reference count indicating a number of processes currently having access to the resource.

48. The method of claim 47, further comprising the steps of

receiving a second request to terminate access to an identified resource;

and

decrementing the reference count corresponding to the identified resource.

49. The method of claim 47, wherein the releasing step includes the substep of

invoking a garbage collection process to reclaim the resource when the reference count indicates no processes currently access the identified resource.

50. The method of claim 43, wherein the releasing step includes the substep of

invoking a garbage collection process to reclaim the resource when access to the resource is no longer requested.

51. The method of claim 43, wherein the permitting step includes the substep of

guaranteeing integrity of the resource for the granted lease period.

52. An apparatus for managing resources comprising:

a receiving component configured to receive a request for a resource and specifying a requested lease period;

an accessing component configured to permit access to the resource for a granted lease period based on the requested lease period; and

a releasing component configured to release the resource when the granted lease period expires.

53. The apparatus of claim 52, wherein the accessing component includes:

a determining component configured to determine the granted lease period to be a period less than the requested lease period.

54. The apparatus of claim 52, wherein the accessing component includes:

a determining component configured to determine the granted lease period based on at least one of the requested lease period, a measure of the resource, and other granted lease periods for the resource.

55. The apparatus of claim 52, wherein the accessing component includes:

a designating component configured to designate the resource upon a determination that access to the resource was not previously permitted.

56. The apparatus of claim 52, wherein the accessing component includes:

an incrementing component configured to increment a reference count corresponding to the resource, the reference count indicating a number of processes currently having access to the resource.

57. The apparatus of claim 56, further comprising:

a receiving component configured to receive a second request to terminate access to an identified resource; and

a decrementing component configured to decrement the reference count corresponding to the identified resource.

58. The apparatus of claim 56, wherein the releasing component includes:

a component configured to invoke a garbage collection process to reclaim the resource when the reference count indicates no processes currently access the identified resource.

59. The apparatus of claim 52, wherein the releasing component includes:

a component configured to invoke a garbage collection process to reclaim the resource when access to the resource is no longer requested.

60. The apparatus of claim 52, wherein the accessing component includes:

a component configured to guarantee integrity of the resource for the granted lease period.

61. A computer program product comprising a computer usable medium having computer readable code embodied therein for managing resources, comprising:

a receiving module configured to receive a request for a resource and specifying a requested lease period;

an accessing module configured to permit access to the resource for a granted lease period based on the requested lease period; and

a releasing module configured to release the resource when the granted lease period expires.

62. The computer program product of claim 61, wherein the accessing module includes:

a determining module configured to determine the granted lease period to be a period less than the requested lease period.

63. The computer program product of claim 61, wherein the accessing module includes:

a determining module configured to determine the granted lease period based on at least one of the requested lease period, a measure of the resource, and other granted lease periods for the resource.

64. The computer program product of claim 61, wherein the accessing module includes:

a designating module configured to designate the resource upon a determination that access to the resource was not previously permitted.

65. The computer program product of claim 61, wherein the accessing module includes:

an incrementing module configured to increment a reference count corresponding to the resource, the reference count indicating a number of processes currently having access to the resource.

66. The computer program product of claim 65, further comprising:

a receiving module configured to receive a second request to terminate access to an identified resource; and

a decrementing module configured to decrement the reference count corresponding to the identified resource.

67. The computer program product of claim 65, wherein the releasing module includes:

a module configured to invoke a garbage collection process to reclaim the resource when the reference count indicates no processes currently access the identified resource.

68. The computer program product of claim 61, wherein the releasing module includes:

a module configured to invoke a garbage collection process to reclaim the resource when access to the resource is no longer requested.

69. The computer program product of claim 61, wherein the accessing module includes:

a module configured to guarantee integrity of the resource for the granted lease period.

70. A computer system comprising:

a computer processor;

a memory which is operatively coupled to the computer processor; and

a computer process which executes in the computer processor for the memory and which includes;

a receiving module configured to receive a request for a resource and specifying a requested lease period;

an accessing module configured to permit access to the resource for a granted lease period based on the requested lease period; and

a releasing module configured to release the resource when the granted lease period expires.