METHOD AND APPARATUS FOR LOADING CLASSES AND RE-ORGANIZING CLASS ARCHIVES

• US 20090217022A1
• Filed: 02/26/2009
• Published: 08/27/2009
• Est. Priority Date: 02/27/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Li, Xin Hui, Xiao, Wen Peng, Chi, Chang Yan
• Granted Patent: US 9,477,496 B2
• Time in Patent Office: Days
• US Class Current: 713/1
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading

Abstract

A method and apparatus for loading classes to virtual machines and a method and apparatus for reorganizing class archives. The method for loading a class to a virtual machine includes organizing a class archive before class loading such that the organized class archive includes a class contraction portion and loading only the class contraction portion of the class archive to the virtual machine at the moment of class loading. By first loading the class contraction portion from the organized class archive to the virtual machine at the moment of loading, the present invention curtails code redundancy, shortens loading time and reduces occupied memory resources.

Claims

1. A method for loading a class to a virtual machine, comprising:

organizing a class archive before class loading such that the organized class archive includes a class contraction portion; and

loading only said class contraction portion of said class archive to the virtual machine.

2. The method according to claim 1, wherein said class contraction portion includes a skeleton for describing basic class information.

3. The method according to claim 1, further comprising:

recording class usage information at runtime; and

reorganizing the class archive according to said class usage information such that said class archive includes the class contraction portion to be loaded.

4. The method according to claim 1, wherein said class contraction portion includes a skeleton of a class to be used describing basic class information and contents to be used of said class describing detailed class information.

5. The method according to claim 4, wherein:

said class usage information comprises one or more of a miss rate of skeletons or contents, missed skeletons or contents and a non-usage rate of skeletons or contents, said missed skeletons or contents being recorded in a first-in first-out manner using a storage space with a fixed size;

said skeletons or contents are added to the class contraction portion when said miss rate exceeds a predetermined threshold;

said skeletons or contents left in said storage space at the end of running are added to the class contraction portion; and

said skeletons or contents are removed from the class contraction portion when said non-usage rate exceeds another predetermined threshold.

6. The method according to claim 3, further comprising:

recording the loading sequence of the class at the moment of loading; and

sorting said class contraction portion in accordance with said loading sequence such that sorting of said class contraction portion is consistent with said loading sequence.

7. The method according to claim 1, further comprising:

carrying out internal verification during class loading; and

carrying out verification of symbolic references during execution of bytecodes.

8. An apparatus for loading a class to a virtual machine, comprising:

a class loader; and

a class archive having a class contraction portion;

wherein said class archive is organized before class loading such that the organized class archive includes the class contraction portion of said class archive; and

wherein said class loader is configured to load only said class contraction portion of said class archive to the virtual machine.

9. The apparatus according to claim 8, wherein said class contraction portion includes a skeleton for describing basic class information.

10. The apparatus according to claim 8, further comprising:

a run recorder configured to record class usage information at runtime; and

a reorganizer configured to reorganize the class archive according to said class usage information such that said class archive includes the class contraction portion.

11. The apparatus according to claim 8, wherein said class contraction portion includes a skeleton of a class to be used, describing basic class information, and contents to be used of said class, describing detailed class information.

12. The apparatus according to claim 11, wherein:

said class usage information includes one or more of a miss rate of skeletons or contents, missed skeletons or contents and a non-usage rate of skeletons or contents;

said missed skeletons or contents are recorded in a first-in first-out manner using a storage space with a fixed size; and

said reorganizer is configured to reorganize the class archive by;

adding said skeletons or contents to the class contraction portion when said miss rate exceeds a predetermined threshold;

adding skeletons or contents left in said storage space at the end of running to the class contraction portion;

or

removing said skeletons or contents from the class contraction portion when said non-usage rate exceeds another predetermined threshold.

13. The apparatus according to claim 10, further comprising:

a load tracker configured to record a loading sequence of the class at said moment of loading.

14. The apparatus according to claim 10, wherein said reorganizer is further configured to sort said class contraction portion in accordance with said loading sequence such that the sorting of said class contraction portion is consistent with said loading sequence.

15. The apparatus according to claim 8, further comprising:

a security verifier configured to carry out (i) internal verification during class loading and (ii) verification of symbolic references during execution of bytecodes.

16. A method for reorganizing a class archive, comprising:

organizing said class archive to include a class contraction portion; and

loading only the class contraction portion of said class archive.

17. The method according to claim 16, further comprising:

separating a class into a skeleton describing basic class information and contents describing detailed class information, and causing said class contraction portion to only include the skeleton of the class.

18. The method according to claim 16, wherein said organizing is carried out according to class usage information at runtime to cause said class contraction portion to only include a skeleton of a class to be used describing basic class information and contents to be used of said class describing detailed class information.

19. The method according to claim 16, wherein an original reorganizing of the class archive is carried out on said class archive to transform original class information in said class archive into a plurality of different class files.

20. The method according to claim 19, wherein contents describing detailed class information are separated into one or more class archives in accordance with the granularity required for loading.