Multi-section garbage collection

• US 10,223,257 B2
• Filed: 07/27/2015
• Issued: 03/05/2019
• 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:
  US14/809,852
• Publication Number:
  US 20170031813A1
• Time in Patent Office: 1,317 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

Apparatus for a garbage collection is disclosed herein. The apparatus includes a processor that includes a load-monitored region register. A memory stores program code, which, when executed on the processor performs an operation for garbage collection, the operation includes specifying a load-monitored region within a memory managed by a runtime environment; enabling a load-monitored event-based branch configured to occur responsive to executing a first type of CPU instruction to load a pointer that points to a first location in the load-monitored region; performing a garbage collection process in background without pausing executing in the runtime environment; executing a CPU instruction of the first type to load a pointer that points to the first location in the load-monitored region; responsive to triggering a load-monitored event-based branch, moving an object pointed to by the pointer with a handler from the first location in memory to a second location in memory.

Claims

1. A system, comprising:

a processor, comprising;

a load-monitored region register; and

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

specifying a load-monitored region within a memory managed by a runtime environment;

enabling a load-monitored event-based branch configured to occur responsive to executing a first type of CPU instruction to load a pointer that points to a first location in the load-monitored region;

performing a garbage collection process in the load-monitored region in background without pausing executing in the runtime environment;

during the garbage collection process, executing a CPU instruction of the first type to load a pointer that points to the first location in the load-monitored region;

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

2. The system of claim 1, wherein the operation further comprises:

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

3. The system of claim 1, wherein enabling the load-monitored event-based branch comprises verifying that the load-monitored event-based branch was caused by a garbage collection hardware.

4. The system of claim 1, wherein the operation further comprises:

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

5. The system of claim 4, wherein the operation further comprises:

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

6. The system of claim 1, wherein moving the object pointed to by the pointer with the handler from the first location in memory to the second location in memory comprises:

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

7. The system of claim 1, wherein the operation further comprises:

responsive to triggering the load-monitored event-based branch and not moving the object to a second location in memory, emulating access to the object at the first location in memory.

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

specifying a load-monitored region within a memory managed by a runtime environment;

enabling a load-monitored event-based branch configured to occur responsive to executing a first type of CPU instruction to load a pointer that points to a first location in the load-monitored region;

performing a garbage collection process in the load-monitored region in background without pausing executing in the runtime environment;

during the garbage collection process, executing a CPU instruction of the first type to load a pointer that points to the first location in the load-monitored region; and

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

9. The computer readable storage medium of claim 8, further comprising:

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

10. The computer readable storage medium of claim 8, wherein enabling the load-monitored event-based branch comprises verifying that the load-monitored event-based branch was caused by a garbage collection hardware.

11. The computer readable storage medium of claim 8, further comprising:

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

12. The computer readable storage medium of claim 11, further comprising:

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

13. The computer readable storage medium of claim 8, wherein moving the object pointed to by the pointer with the handler from the first location in memory to the second location in memory comprises:

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