Timely finalization of system resources

• US 7,069,279 B1
• Filed: 11/04/2002
• Issued: 06/27/2006
• Est. Priority Date: 11/04/2002
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: SavaJe Technologies, Inc. (Oracle Corporation)
• Inventors: Rau, Lawrence R., Barrus, Frank E., Newell, Craig F.
• Primary Examiner(s): ALAM, SHAHID AL
• Application Number:
  US10/287,858
• Time in Patent Office: 1,331 Days
• Field of Search: 707/10, 707/103.R, 707/204, 707/205, 707/206, 707/2, 707/102, 714/53, 714/35, 717/116, 717/148, 717/154, 711/2, 711/200
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 9/5016 the resource being the memory
• CPC Class Codes: G06F 9/5022 Mechanisms to release resources
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99957 Garbage collection

Abstract

A garbage collector, from time to time, and within a single cycle, determines objects that are eligible to have their associated memory freed; executes high-priority finalizers associated with such eligible objects as are determined; and after execution of a high-priority finalizer, deallocates the memory of the associated object. The garbage collector queues references to eligible objects that have non-high-priority finalizers in a list. After garbage collection is completed, a finalizer thread runs the queued non-high-priority finalizers and marks the associated objects as ready for deallocation. The garbage collector, during a subsequent cycle, then deallocates the memory associated with marked objects.

Claims

1. A method for deallocating memory, comprising:

upon determining that an object associated with a high-priority finalizer capable of executing at a system level is eligible to have said object'"'"'s memory freed, executing the high-priority finalizer;

deallocating, upon completion of said executing of said high-priority finalizer, said object'"'"'s memory;

performing within one garbage collection cycle said deallocating and said executing to minimize latency;

executing, at indeterminate times, non-high-priority finalizers associated with objects eligible for deallocation, said objects becoming unreachable; and

freeing, at an indeterminate time relative to when an object'"'"'s non-high-priority finalizer is executed, memory associated with said object.

2. The method of claim 1, wherein the high-priority finalizer is executed by a garbage collector.

3. The method of claim 2, wherein the garbage collector is a mark-and-sweep garbage collector.

4. The method of claim 1, wherein the system is a shared object system which has access to objects of different applications.

5. The method of claim 1, wherein said method executes within a Java Virtual Machine.

6. The method of claim 1, wherein high-priority finalizers are identified using an existing method declaration attribute.

7. The method of claim 6, wherein said existing method declaration attribute is “

native”

.

8. The method of claim 1, wherein high-priority finalizers are identified through explicit calls to a system registration method during object creation.

9. A system for deallocating memory, comprising:

means for executing a high-priority finalizer capable of executing at a system level upon a determination that an object associated with said high-priority finalizer is eligible to have said object'"'"'s memory freed;

means for deallocating said object'"'"'s memory upon completion of said means for executing said high-priority finalizer, wherein said

means for reallocating and said means for executing perform the high-priority finalizer and reallocating in one garbage collection cycle to minimize latency;

means for executing, at indeterminate times, non-high-priority finalizers associated with objects eligible for deallocation, said objects becoming unreachable; and

means for freeing, at an indeterminate time relative to when an object'"'"'s non-high-priority finalizer is executed, memory associated with said object.