Function Evaluation using Lightweight Process Snapshots

• US 20140040897A1
• Filed: 08/04/2012
• Published: 02/06/2014
• Est. Priority Date: 08/04/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Davis, Jackson, Kim, Tae Hyung
• Granted Patent: US 9,710,357 B2
• Time in Patent Office: Days
• US Class Current: 718/100
• CPC Class Codes: G06F 11/3096 wherein the means or processing minimize the use of computing system or of computing system component resources, e.g. non-intrusive monitoring which minimizes the probe effect: sniffing, intercepting, indirectly deriving the monitored data from other directly available data
• CPC Class Codes: G06F 11/362 Software debugging
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 11/366 using diagnostics G06F11/0703 takes precedence

Abstract

A debugger creates a lightweight process snapshot of a debuggee target process and performs in-process or function evaluation (func-eval) inspection against the copy. This allows most state in the debuggee process to stay intact because changes made by the func-eval are local to the process snapshot. Debugger operations that are too destructive to the original debuggee process can be performed on the process snapshot without threatening the real process. Process snapshots allow the debugger to perform a func-eval while isolating the debuggee process and not losing the actual state of the original debuggee process. A new process snapshot of the debuggee process is created when the current snapshot is corrupt due to a func-eval side effect. The debugger may also use a lightweight machine snapshot of the host debuggee machine and perform func-evals against that machine snapshot to further isolate kernel and other side effects.

Claims

1. In a computing environment, a method of debugging a target process, the method comprising:

generating a lightweight process snapshot from the target process, with the lightweight process snapshot and target process allowed to run independently; and

performing function evaluations against the lightweight process snapshot.

2. The computer-implemented method of claim 1, wherein side effects of the function evaluation of the lightweight process snapshot are isolated from the target process.

3. The computer-implemented method of claim 1, further comprising:

identifying when the lightweight process snapshot no longer represents the target process due to side effects of the function evaluation or because the lightweight process snapshot has been corrupted; and

creating a new lightweight process snapshot of the target process.

4. The computer-implemented method of claim 1, further comprising:

detecting a deadlock while performing the function evaluation;

generating a second lightweight process snapshot from the target process; and

performing function evaluations against the second lightweight process snapshot while allowing all threads to execute during the function evaluation.

5. The computer-implemented method of claim 4, wherein the threads in the target process are allowed to execute to avoid deadlocking the target process when inter-thread dependencies are encountered.

6. The computer-implemented method of claim 1, further comprising:

allowing all threads in the lightweight snapshot process to execute during the function evaluation to avoid deadlocking the snapshot process.

7. The computer-implemented method of claim 1, further comprising:

creating a lightweight machine snapshot of a machine hosting the target process;

running the lightweight process snapshot on the lightweight machine snapshot; and

performing the function evaluation against the lightweight process snapshot that is running on the lightweight machine snapshot.

8. The computer-implemented method of claim 7, further comprising:

allowing all threads in the target process to execute during the function evaluation to avoid deadlocking the target process when inter-thread dependencies are encountered.

9. The computer-implemented method of claim 7, wherein side effects of the function evaluation on the lightweight machine snapshot are isolated from the target process and from the target process'"'"'s kernel.

10. The computer-implemented method of claim 7, further comprising:

identifying when the lightweight process snapshot no longer represents the target process due to side effects of the function evaluation; and

creating a new lightweight machine snapshot.

11. The computer-implemented method of claim 1, further comprising:

identifying when the lightweight process snapshot has been corrupted and no longer represents the target process; and

creating a new lightweight machine snapshot.

15. The computer system of claim 1, further comprising:

identifying when the lightweight process snapshot no longer represents the target process due to side effects of the function evaluation or when the lightweight process snapshot has been corrupted; and

creating a new lightweight process snapshot of the target process.

17. The computer-implemented method of claim 7, wherein side effects of the function evaluation on the lightweight machine snapshot are isolated from the target process.

12. In a computing environment, a computer system including functionality for debugging a target process, the computer system comprising:

one or more processors;

one or more computer readable media;

one or more computer modules implemented as computer executable instructions stored on the computer readable media, that when executed by one or more processors, cause the processors to perform the following;

generating a lightweight process snapshot from the target process, with the lightweight process snapshot and target process allowed to run independently; and

performing function evaluations against the lightweight process snapshot.

13. The computer system of claim 12, further comprising:

allowing all threads in the target process to execute during the function evaluation to avoid deadlocking the target process when inter-thread dependencies are encountered.

14. The computer system of claim 12, wherein side effects of the function evaluation of the lightweight process snapshot are isolated from the target process.

16. The computer system of claim 12, further comprising:

creating a lightweight machine snapshot of a machine hosting the target process;

running the lightweight process snapshot on the lightweight machine snapshot; and

performing the function evaluation against the lightweight process snapshot that is running on the lightweight machine snapshot.

18. In a computing environment, a computer readable medium comprising computer executable instructions that when executed by one or more processor cause the one or more processor to perform the following:

generating a lightweight process snapshot from the target process, with the lightweight process snapshot and target process allowed to run independently; and

performing function evaluations against the lightweight process snapshot.

20. The computer readable medium of claim 18, further comprising:

creating a lightweight machine snapshot of a machine hosting the target process;

running the lightweight process snapshot on the lightweight machine snapshot; and

performing the function evaluation against the lightweight process snapshot that is running on the lightweight machine snapshot and isolated from the target process and the target process'"'"'s kernel.

19. The computer readable medium of claim 19, further comprising:

allowing all threads in the target process to execute during the function evaluation to avoid deadlocking the target process when inter-thread dependencies are encountered; and

wherein side effects of the function evaluation of the lightweight process snapshot are isolated from the target process.