Multi-section garbage collection

• US 10,838,857 B2
• Filed: 12/05/2017
• Issued: 11/17/2020
• Est. Priority Date: 07/27/2015
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Frazier, Giles R., Gschwind, Michael Karl, Manton, Younes, Taylor, Karl M., Thompto, Brian W.
• Primary Examiner(s): Partridge, William B
• Application Number:
  US15/832,207
• Publication Number:
  US 20180095874A1
• Time in Patent Office: 1,078 Days
• Field of Search: None
• 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 9/45504 Abstract machines for programme code execution, e.g. Java virtual machine [JVM], interpreters, emulators

Abstract

A method and apparatus for garbage collection is disclosed herein. The method includes performing a garbage collection process without pausing execution of a runtime environment. The method also includes executing a first CPU instruction to load a first pointer that points to a first location in a first region of memory, where the first region of memory is undergoing garbage collection. The method also includes moving a first object pointed to by the first pointer from the first location in memory to a second location in memory.

Claims

1. A method comprising:

performing a garbage collection process without pausing execution of a runtime environment;

executing a first CPU instruction to load a first pointer that points to a first location in a first region of memory, wherein the first region of memory is undergoing garbage collection; and

responsive to triggering an event based branch, moving a first object pointed to by the first pointer from the first location in memory to a second location in memory.

2. The method of claim 1, the method further comprising:

specifying a load-monitored region within the memory, wherein the load-monitored region of memory is currently undergoing garbage collection.

3. The method of claim 1, further comprising:

updating a table that tracks the movement of the first object pointed to by the first pointer from the first location in memory to a second location in memory.

4. The method of claim 2, further comprising:

loading the specified load-monitored region into a load-monitored region register.

5. The method of claim 4, further comprising:

enabling a section of the specified load-monitored region into a load-monitored section enable register.

6. The method of claim 1, wherein moving the first object comprises:

copying the first object from the first location in memory to the second location in memory and updating the first pointer to point to the first object in the second location of memory.

7. The method of claim 2, further comprising:

executing a second CPU instruction to load a second pointer that points to a third location in the load-monitored region;

not moving the second object to a fourth location in memory; and

emulating access to the second object at the third location in memory.

8. A system, comprising:

a processor;

a memory storing program code, which, when executed on the processor performs an operation comprising;

performing a garbage collection process without pausing execution of a runtime environment;

executing a first CPU instruction to load a first pointer that points to a first location in a first region of memory, wherein the first region of memory is undergoing garbage collection; and

responsive to triggering an event based branch, moving a first object pointed to by the first pointer from the first location in memory to a second location in memory.

9. The system of claim 8, the operation further comprising:

specifying a load-monitored region within the memory, wherein the load-monitored region of memory is currently undergoing garbage collection.

10. The system of claim 8, wherein the operation further comprises:

updating a table that tracks the movement of the first object pointed to by the first pointer from the first location in memory to a second location in memory.

11. The system of claim 9, wherein the operation further comprises:

loading the specified load-monitored region into a load-monitored region register.

12. The system of claim 11, wherein the operation further comprises:

enabling a section of the specified load-monitored region into a load-monitored section enable register.

13. The system of claim 8, wherein moving the first object comprises:

copying the first object from the first location in memory to the second location in memory and updating the first pointer to point to the first object in the second location of memory.

14. The system of claim 9, wherein the operation further comprises:

executing a second CPU instruction to load a second pointer that points to a third location in the load-monitored region;

not moving the second object to a fourth location in memory; and

emulating access to the second object at the third location in memory.

15. A computer readable non-transitory storage medium having stored thereon instructions that when executed by a processor cause the processor to perform an operation comprising:

performing a garbage collection process without pausing execution of a runtime environment;

executing a first CPU instruction to load a first pointer that points to a first location in a first region of memory, wherein the first region of memory is undergoing garbage collection; and

responsive to triggering an event based branch, moving a first object pointed to by the first pointer from the first location in memory to a second location in memory.

16. The computer readable non-transitory storage medium of claim 15, the operation further comprising:

specifying a load-monitored region within the memory, wherein the load-monitored region of memory is currently undergoing garbage collection.

17. The computer readable non-transitory storage medium of claim 15, further comprising:

updating a table that tracks the movement of the first object pointed to by the first pointer from the first location in memory to a second location in memory.

18. The computer readable non-transitory storage medium of claim 16, further comprising:

loading the specified load-monitored region into a load-monitored region register.

19. The computer readable non-transitory storage medium of claim 18, further comprising:

enabling a section of the specified load-monitored region into a load-monitored section enable register.

20. The computer readable non-transitory storage medium of claim 15, wherein moving the first object comprises:

copying the first object from the first location in memory to the second location in memory and updating the first pointer to point to the first object in the second location of memory.