Queue debugging using stored backtrace information

• US 9,378,117 B2
• Filed: 05/30/2014
• Issued: 06/28/2016
• Est. Priority Date: 05/30/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Payne, David Vernon, Steffen, Daniel Andreas, Ong, Han Ming, Molenda, Jason, Orr, Kenneth Scott, Stone, Katherine Blake
• Primary Examiner(s): KENDALL, CHUCK O
• Application Number:
  US14/292,777
• Publication Number:
  US 20150347271A1
• Time in Patent Office: 760 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program

Abstract

When queuing work items for asynchronous execution, the approaches set forth herein enable a debugger to provide more meaningful and complete stack trace information for enqueued work items. An example system identifies a work item to be enqueued for asynchronous execution as a separate thread during runtime of a program. Upon enqueuing the work item in an execution queue, the system captures pre-queue stack trace information associated with the work item, and associates the pre-queue stack trace information with the work item. The system removes the work item from the execution queue for execution, wherein the execution is associated with current stack trace information separate from the pre-queue stack trace information. Upon detecting an event associated with executing the work item, the system merges the pre-queue stack trace information with the current stack trace information to yield a merged stack trace.

Claims

1. A method comprising:

identifying a task to be enqueued for asynchronous execution as a separate thread during runtime of a program;

upon enqueuing the task in an execution queue, capturing pre-queue stack trace information associated with the task, wherein stack trace information comprises debugging information that provides a backtrace to at least one portion of a program that caused the task to become enqueued;

associating the pre-queue stack trace information with the task;

removing the task from the execution queue for execution, wherein the execution is associated with current stack trace information separate from the pre-queue stack trace information;

upon detecting an event associated with executing the task, merging the pre-queue stack trace information with the current stack trace information to yield a merged stack trace; and

if the event is not detected upon completion of the execution of the task, removing the pre-queue stack trace information and the current stack trace information.

2. The method of claim 1, wherein the event comprises at least one of a crash of the program, an exception in the program, thread creation, thread execution, thread termination, or thread destruction.

3. The method of claim 1, wherein the event comprises at least one of receiving a request from a debugger for a stack trace for the task, pausing the program, or encountering a breakpoint in the program.

4. The method of claim 1, wherein the pre-queue stack trace information comprises information about a source of the task and at least a portion of a stack frame of the queue at the time the task was enqueued.

5. The method of claim 1, wherein a modified dispatch library captures the pre-queue stack trace information associated with the task, associates the pre-queue stack trace information with the task, and merges the pre-queue stack trace information with the current stack trace information, and wherein a pruner removes the pre-queue stack trace information and the current stack trace information.

6. The method of claim 1, wherein the pre-queue stack trace information is associated with the task via a hook function.

26. The method of claim 1, wherein an event comprises at least one of:

a crash, an exception, a pause, or a breakpoint in a process, task, thread, or program.

27. The method of claim 1, wherein an event comprises at least one of:

a work item creation, a work item execution, a work item termination, or a work item destruction.

7. A system comprising:

a processor; and

a computer-readable memory device storing instructions which, when executed by the processor, cause the processor to perform operations comprising;

upon enqueuing a process in a queue for later asynchronous execution, storing in a memory pre-queue stack trace information associated with the process, wherein stack trace information comprises debugging information that provides a backtrace to at least one portion of a program that caused the process to become enqueued;

upon dequeuing the process from the queue for execution, identifying postqueue stack trace information associated with the process; and

merging the pre-queue stack trace information with the post-queue stack trace information to yield a merged stack trace for the process.

8. The system of claim 7, the instructions, when executed by the processor, causing the processor to perform operations further comprising:

identifying a second process in the queue having pre-queue stack trace information that is within a threshold similarity to the pre-queue stack trace information of the process; and

representing the pre-queue stack trace information of the process and the second process in the memory in a compressed format.

9. The system of claim 8, wherein the threshold similarity is an exact match.

10. The system of claim 8, wherein the compressed format comprises one of sharing same pre-queue stack trace information between the process and the second process, and storing a set of changes from the pre-queue stack trace information for the process, wherein the set of changes is associated with the second process.

11. The system of claim 7, wherein a custom dispatch library manages storing the prequeue stack trace information, identifying post-queue stack trace information, and merging the pre-queue stack trace information with the post-queue stack trace information.

12. The system of claim 11, wherein the custom dispatch library is part of a debugger, and wherein the debugger toggles between a standard dispatch library and the custom dispatch library.

13. The system of claim 7, the instructions, when executed by the processor, causing the processor to perform operations further comprising:

identifying, prior to enqueuing the process, that the process is flagged to maintain stack trace information through the queue.

14. The system of claim 7, the instructions, when executed by the processor, causing the processor to perform operations further comprising:

after execution of the process, removing the pre-queue stack trace information and the post-queue stack trace information.

15. A non-transitory computer-readable storage device having stored therein instructions which, when executed by a processing device, cause the processing device to perform operations comprising:

enqueuing, via a debugger, a thread in an execution queue for asynchronous execution;

associating, via a hook function, pre-queue stack trace information with the thread, wherein stack trace information comprises debugging information that provides a backtrace to at least one portion of a program that caused the thread to become enqueued;

removing the thread from the execution queue for execution; and

merging the pre-queue stack trace information with current stack trace information to yield a merged stack trace, wherein the current stack trace information is separate from the pre-queue stack trace information prior to merging.

16. The non-transitory computer-readable storage device of claim 15, the instructions, when executed by the processing device, causing the processing device to perform operations further comprising:

removing at least one of the pre-queue stack trace information, the current stack trace information, and the merged stack trace.

17. The non-transitory computer-readable storage device of claim 15, the instructions, when executed by the processing device, causing the processing device to perform operations further comprising:

upon completion of the execution of the thread, removing at least one of the prequeue stack trace information, the current stack trace information, and the merged stack trace.

18. The non-transitory computer-readable storage device of claim 15, the instructions, when executed by the processing device, causing the processing device to perform operations further comprising:

upon completion of the execution of the thread and any related threads from the queue, removing at least one of the pre-queue stack trace information, the current stack trace information, and the merged stack trace.

19. The non-transitory computer-readable storage device of claim 15, wherein the hook function is inserted as part of an initialization function for a dispatch library associated with the debugger.

20. A system comprising:

a processor; and

a memory device storing instructions which, when executed by the processor, cause the processor to perform operations comprising;

dequeuing a process from an asynchronous execution queue for execution;

establishing, in connection with the execution, post-queue stack trace information, wherein stack trace information comprises debugging information that provides a backtrace to at least one portion of a program that caused the process to become enqueued and subsequently dequeued;

retrieving pre-queue stack trace information associated with the process that was stored prior to dequeuing the process; and

merging the pre-queue stack trace information with the post-queue stack trace information to yield a merged stack trace for the process.

21. The system of claim 20, wherein the pre-queue stack trace information is merged upon receiving an indication of an event comprising at least one of a program crash, a program exception, thread creation, thread execution, thread termination, or thread destruction.

22. The system of claim 20, wherein the pre-queue stack trace information is merged upon receiving an indication of an event comprising at least one of receiving a request from a debugger for a stack trace for the process, pausing a program associated with the process, or encountering a breakpoint in the program.

23. The system of claim 20, wherein the pre-queue stack trace information comprises information about a source of the process.

24. The system of claim 20, wherein the pre-queue stack trace information was stored by a modified dispatch library.

25. The system of claim 20, wherein the pre-queue stack trace information is associated with the process via a hook function.