Methods, apparatus, and product for distributed garbage collection

• US 6,327,596 B1
• Filed: 07/27/1999
• Issued: 12/04/2001
• 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): Choules, Jack
• Assistant Examiner(s): LEWIS, CHERYL RENEA
• Application Number:
  US09/361,190
• Time in Patent Office: 861 Days
• Field of Search: 707/206, 707/201, 707/10, 709/203, 709/104
• 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 objects performed by at least one processor comprising:

sending a request to access an object, including a reference corresponding to the object and indicating a period of time for which access to the object is requested;

receiving a response to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted;

determining whether the period for which access to the object has been permitted is about to expire; and

providing a notification that the period for which access to the object has been permitted is about to expire.

2. The method of claim 1, further comprising:

renewing the request to access the resource based upon a determination that access to the resource is required.

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

incrementing a counter corresponding to the object reflecting the response.

4. The method of claim 1, further comprising:

sending a notification indicating that access to the object is no longer required.

5. The method of claim 4, wherein sending a notification indicating that access to the object is no longer required, includes:

decrementing a counter corresponding to the object reflecting the notification.

6. The method of claim 5, wherein decrementing a counter corresponding to the object reflecting the notification, includes:

invoking a process to collect resources corresponding to the object upon a determination that the counter corresponding to the object indicates that access to this object is no longer required.

7. A method for managing resources comprising the steps, performed by at least one processor, of:

permitting access to a resource for a particular time interval in response to a set of requests for access to the resource;

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

releasing the resource when the time interval expires.

8. The method of claim 7, wherein the permitting operation includes

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

9. The method of claim 7, wherein the releasing operation includes reclaiming the resource when access to the resource is no longer requested.

10. The method of claim 7, wherein the releasing operation includes

reclaiming the resource when the reference count indicates no processes currently access the identified resource.

11. The method of claim 7, wherein the permitting operation includes

guaranteeing integrity of the resource for the time interval.

12. A method for managing objects in a distributed system having a client computer and a server computer, the method comprising:

performing, by the client computer, the steps of;

sending a request to the server computer to access an object, including a reference corresponding to the object and indicating a period of time for which access to the object is requested,

receiving a response from the server computer to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted,

determining whether the period for which access to the object has been permitted is about to expire, and

renewing the request to access the resource based upon a determination that access to the resource is required; and

performing, by the server computer, the steps of;

receiving the request from the client computer to access the object,

sending the response to the request,

determining whether the period for which access to the object has beer permitted has expired, and

collecting a resource corresponding to the object based on the determination.

13. A method for managing objects performed by at least one processor comprising:

sending a request to access an object, including a reference corresponding to the object and indicating a period of time for which access to the object is requested;

receiving a response to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted; and

reclaiming a resource associated with the object when access to the object is no longer required.

14. The method of claim 13, wherein reclaiming a resource further includes decrementing a reference counter, the reference counter counting a number of processes currently having access to the object.

15. A system for managing objects, comprising:

a client computer for sending a request to access an object, wherein the request includes a reference corresponding to the object and indicating a period of time for which access to the object is requested; and

a server computer for receiving the request to access the object from the client computer, generating a response to the request indicating a period of time for which access to the object on a nonexclusive basis is permitted, determining whether the period of time for which access to the object has been permitted is expired and collecting a resource corresponding to the object in response to determining that the period of time for which access to the object is permitted has expired.

16. The system of claim 15, wherein the server computer includes a counter for indicating whether or not access to the object is required, and wherein the counter is incremented when the client computer is granted access to the object, and the counter is decremented when a notification is received from the client computer that access to the object is no longer required.