MEMORY ALLOCATION FOR LONG-LIVED OBJECTS

• US 20140082315A1
• Filed: 09/14/2012
• Published: 03/20/2014
• Est. Priority Date: 09/14/2012
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Moser, Martin
• Granted Patent: US 10,120,796 B2
• Time in Patent Office: Days
• US Class Current: 711/170
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 12/0276 Generational garbage collection

Abstract

Managing memory allocations in a computer system may include tagging a class of data structures with a tag that identities a longer memory-allocation time for objects that correspond to the class. In response to a memory-allocation request for an object, whether or not the object is associated with the tag can be determined through the class. If the object is not associated with the tag, memory can be allocated for the object from a first memory-allocation area that corresponds to a shorter memory-allocation time, and if the object is associated with the tag, memory can be allocated for the object from a second memory-allocation area that corresponds to the longer memory-allocation time.

Claims

1. A method of managing memory allocations in a computer system, the method comprising:

tagging a class of data structures with a tag that identifies a longer memory-allocation time for objects that correspond to the class;

in response to a memory-allocation request for an object, determining whether or not the object is associated with the tag through the class;

if the object is not associated with the tag, allocating memory for the object from a first memory-allocation area that corresponds to a shorter memory-allocation time; and

if the object is associated with the tag, allocating memory for the object from a second memory-allocation area that corresponds to the longer memory-allocation time.

2. The method of claim 1, wherein the object instantiates the class in an object-oriented programming system.

3. The method of claim 1, further comprising:

using a portion of an object header corresponding to the class to represent the tag; and

determining that the object is associated with the tag by identifying that the object instantiates the class and inspecting the portion of the object header where the tag is represented.

4. The method of claim 1, wherein

tagging the class includes associating a marker interface with the class;

and

determining whether or not the object is associated with the tag includes determining whether or not the object supports the marker interface through the class.

5. The method of claim 1, wherein

tagging the class includes associating a marker annotation with the class;

and

determining whether or not the object is associated with the tag includes determining whether or not the object identifies the marker annotation through the class.

6. The method of claim 1, further comprising:

performing first memory-management operations in the first memory-allocation area, the first memory-management operations being carried out at intervals corresponding to a first time increment;

performing second memory-management operations in the second memory-allocation area, the second memory-management operations being carried out at intervals corresponding to a second time increment, the second time increment being greater than the first time increment; and

transferring a memory allocation for a first object from the first memory-allocation area to the second memory-allocation area if a corresponding memory-allocation time for the first object reaches a threshold value for memory-allocation time in the first memory-allocation area.

7. The method of claim 1, further comprising:

performing first memory-management operations in the first memory-allocation area, the first memory-management operations including operations that copy first-memory-allocation-area survivors from a first portion of the first memory-allocation area to a second portion of the first memory-allocation area;

performing second memory-management operations in the second memory-allocation area, the second memory-management operations including operations that mark second-memory-allocation-area survivors and copy the second-memory-allocation-area survivors into available portions of the second memory-allocation area; and

transferring a memory allocation for a first object from the first memory-allocation area to the second memory-allocation area if a corresponding memory-allocation time for the first object reaches a threshold value for memory-allocation time in the first memory-allocation area.

8. The method of claim 1, wherein the class identifies objects that are expected to persist for a threshold number of computing cycles.

9. A non-transitory computer-readable medium that stores a computer program for managing memory allocations in a computer system, the computer program including instructions that, when executed by at least one computer, cause the at least one computer to perform operations comprising:

tagging a class of data structures with a tag that identifies a longer memory-allocation time for objects that correspond to the class;

in response to a memory-allocation request for an object, determining whether or not the object is associated with the tag through the class;

if the object is not associated with the tag, allocating memory for the object from a first memory-allocation area that corresponds to a shorter memory-allocation time; and

if the object is associated with the tag, allocating memory for the object from a second memory-allocation area that corresponds to the longer memory-allocation time.

10. The non-transitory computer-readable medium of claim 9, wherein the object instantiates the class in an object-oriented programming system.

11. The non-transitory computer-readable medium of claim 9, wherein the computer program further includes instructions that, when executed by the at least one computer, cause the at least one computer to perform operations comprising:

using a portion of an object header corresponding to the class to represent the tag; and

determining that the object is associated with the tag by identifying that the object instantiates the class and inspecting the portion of the object header where the tag is represented.

12. The non-transitory computer-readable medium of claim 9, wherein

tagging the class includes associating a marker interface with the class;

and

determining whether or not the object is associated with the tag includes determining whether or not the object supports the marker interface through the class.

13. The non-transitory computer-readable medium of claim 9, wherein

tagging the class includes associating a marker annotation with the class;

and

determining whether or not the object is associated with the tag includes determining whether or not the object identifies the marker annotation through the class.

14. The non-transitory computer-readable medium of claim 9, wherein the computer program further includes instructions that, when executed by the at least one computer, cause the at least one computer to perform operations comprising:

performing first memory-management operations in the first memory-allocation area, the first memory-management operations being carried out at intervals corresponding to a first time increment;

performing second memory-management operations in the second memory-allocation area, the second memory-management operations being carried out at intervals corresponding to a second time increment, the second time increment being greater than the first time increment; and

transferring a memory allocation for a first object from the first memory-allocation area to the second memory-allocation area if a corresponding memory-allocation time for the first object reaches a threshold value for memory-allocation time in the first memory-allocation area.

15. The non-transitory computer-readable medium of claim 9, wherein the computer program further includes instructions that, when executed by the at least one computer, cause the computer to perform operations comprising:

performing first memory-management operations in the first memory-allocation area, the first memory-management operations including operations that copy first-memory-allocation-area survivors from a first portion of the first memory-allocation area to a second portion of the first memory-allocation area;

performing second memory-management operations in the second memory-allocation area, the second memory-management operations including operations that mark second-memory-allocation-area survivors and copy the second-memory-allocation-area survivors into available portions of the second memory-allocation area; and

transferring a memory allocation for a first object from the first memory-allocation area to the second memory-allocation area if a corresponding memory-allocation time for the first object reaches a threshold value for memory-allocation time in the first memory-allocation area.

16. The non-transitory computer-readable medium of claim 9, wherein the class identifies objects that are expected to persist for a threshold number of computing cycles.

17. An apparatus to manage memory allocations in a computer system, the apparatus comprising at least one computer configured to perform operations for computer-executable modules including:

a class-tagging module that tags a class of data structures with a tag that identifies a longer memory-allocation time for objects that correspond to the class;

an object-tagging module that, in response to a memory-allocation request for an object, determines whether or not the object is associated with the tag through the class; and

a memory-allocation module that performs operations including;

if the object is not associated with the tag, allocating memory for the object from a first memory-allocation area that corresponds to a shorter memory-allocation time; and

if the object is associated with the tag, allocating memory for the object from a second memory-allocation area that corresponds to the longer memory-allocation time.

18. The apparatus of claim 17, wherein the object instantiates the class in an object-oriented programming system.

19. The apparatus of claim 17, wherein

the class-tagging module uses a portion of an object header corresponding to the class to represent the tag;

and

the object-tagging module determines that the object is associated with the tag by identifying that the object instantiates the class and inspecting the portion of the object header where the tag is represented.

20. The apparatus of claim 17, wherein

tagging the class includes associating a marker interface with the class;

and

determining whether or not the object is associated with the tag includes determining whether or not the object supports the marker interface through the class.

21. The apparatus of claim 17, wherein

tagging the class includes associating a marker annotation with the class;

and

determining whether or not the object is associated with the tag includes determining whether or not the object identifies the marker annotation through the class.

22. The apparatus of claim 17, wherein the computer-executable modules further include a memory-management module that performs operations including:

performing first memory-management operations in the first memory-allocation area, the first memory-management operations being carried out at intervals corresponding to a first time increment;

performing second memory-management operations in the second memory-allocation area, the second memory-management operations being carried out at intervals corresponding to a second time increment, the second time increment being greater than the first time increment; and

transferring a memory allocation for a first object from the first memory-allocation area to the second memory-allocation area if a corresponding memory-allocation time for the first object reaches a threshold value for memory-allocation time in the first memory-allocation area.

23. The apparatus of claim 17, wherein the computer-executable modules further include a memory-management module that performs operations including:

performing first memory-management operations in the first memory-allocation area, the first memory-management operations including operations that copy first-memory-allocation-area survivors from a first portion of the first memory-allocation area to a second portion of the first memory-allocation area;

performing second memory-management operations in the second memory-allocation area, the second memory-management operations including operations that mark second-memory-allocation-area survivors and copy the second-memory-allocation-area survivors into available portions of the second memory-allocation area; and

transferring a memory allocation for a first object from the first memory-allocation area to the second memory-allocation area if a corresponding memory-allocation time for the first object reaches a threshold value for memory-allocation time in the first memory-allocation area.

24. The apparatus of claim 17, wherein the class identifies objects that are expected to persist for a threshold number of computing cycles.