Analysis of thread synchronization events

• US 8,499,287 B2
• Filed: 06/23/2008
• Issued: 07/30/2013
• Est. Priority Date: 06/23/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Adelberg, Brian, Blees, Maria, Janotti, Paulo, Sedky, Khaled, Shafi, Hazin
• Primary Examiner(s): Zhen, Li B
• Assistant Examiner(s): BODDEN, EVRAL E
• Application Number:
  US12/143,863
• Publication Number:
  US 20090319996A1
• Time in Patent Office: 1,863 Days
• Field of Search: None
• US Class Current: 717/125
• CPC Class Codes: G06F 8/314 Parallel programming languages G06F8/313 takes precedence

Abstract

Thread blocking synchronization event analysis software uses kernel context switch data and thread unblocking data to form a visualization of thread synchronization behavior. The visualization provides interactive access to source code responsible for thread blocking, identifies blocking threads and blocked threads, summarizes execution delays due to synchronization and lists corresponding APIs and objects, correlates thread synchronization events with application program phases, and otherwise provides information associated with thread synchronization. The visualization may operate within an integrated development environment.

Claims

1. A method which may be used by a developer to help analyze thread synchronization events, the method comprising the steps of:

receiving the following data for each of a plurality of thread context switches;

switched-in thread identity, switched-out thread identity, switched-out thread state, at least one thread call stack;

determining with the data that a particular switched-out thread was synchronization-blocked; and

outputting a thread synchronization event analysis listing the particular switched-out thread as a blocked thread and listing an indication of a blocking API based on the particular thread call stack and a collection of blocking API identifications, “

API”

being an acronym for Application Program Interface,

wherein the thread synchronization event analysis configures a display with a visible link between (i) an icon representing an unblocking event within a first thread timeline and (ii) a second thread timeline representing a thread which is unblocked by the event, and wherein the first and second timelines are separated in the display by at least one other timeline.

2. The method of claim 1, further comprising:

determining that a particular thread was synchronization-unblocked; and

outputting a thread synchronization event analysis listing the particular thread as an unblocked thread and listing a corresponding unblocking thread.

3. The method of claim 2, wherein the method further comprises receiving context switch times of occurrence and receiving unblocking event times of occurrence, and the method also outputs thread execution periods based on at least some of the times of occurrence.

4. The method of claim 1, further comprising presenting a visualization of the thread synchronization event analysis.

5. The method of claim 4, wherein the visualization provides a user with interactive access to source code responsible for at least one of:

a thread blocking synchronization event, a thread unblocking synchronization event.

6. The method of claim 4, wherein the visualization provides a user with an identification of a blocking thread which holds a synchronization object that is blocked on in a thread blocking synchronization event.

7. The method of claim 4, wherein the visualization correlates thread synchronization event occurrence times with an instrumentation of an application program.

8. A computer system configured to assist analysis of thread synchronization events, the system comprising:

a memory;

a logical processor in operable communication with the memory;

a display in operable communication with the memory and the processor;

thread context switch data produced by a kernel thread scheduler;

thread unblocking data; and

software which receives the following data for each of a plurality of thread context switches;

switched-in thread identity, switched-out thread identity, switched-out thread state, at least one thread call stack;

determines with the data that a particular switched-out thread was synchronization-blocked; and

outputs a thread synchronization event analysis listing the particular switched-out thread as a blocked thread and listing an indication of a blocking API based on the particular thread call stack and a collection of blocking API identifications,

a visualization of the thread context switch data and the thread unblocking data which configures the display and shows thread blocking and thread unblocking synchronization events, the visualization containing a visible link between (i) an icon representing an unblocking event within a first thread timeline and (ii) a second thread timeline representing a thread which is unblocked by the event, the visualization correlating thread synchronization event occurrence times with an instrumentation of an application program.

9. The system of claim 8, wherein the visualization configures the display with an icon for a blocking event, and the system further comprises at least one source code display routine designed to display source code responsible for the blocking event after a user selects the icon.

10. The system of claim 8, wherein the visualization configures the display with a visible link between a blocking event and a thread which holds a synchronization object that is blocked on.

11. The system of claim 8, wherein the visualization configures the display with a visible link between an unblocking event and a thread which is unblocked by the event, and with an indication of how much time passed between the unblocking event and the thread resuming execution.

12. The system of claim 8, wherein the visualization configures the display with a report summarizing the amount of time a thread is blocked, subdivided by at least one of:

synchronization object category, call stack.

13. The system of claim 8, wherein the visualization configures the display with a color-coded report in which different colors correspond to different thread synchronization event categories.

14. The system of claim 8, further comprising an integrated development environment configuring the memory, wherein the visualization is integrated with the integrated development environment for source code access by a user.

15. The system of claim 8, wherein the visualization configures the display with an icon for a blocking event, and the system further comprises at least one blocking event details display routine designed to display details about a synchronization API, a synchronization object, and a call stack at which the blocking event occurred, “

API”

being an acronym for Application Program Interface.

20. The system of claim 8, further comprising a mechanism for a user to identify at least one API which is to be treated as a synchronization blocking API in the visualization, “

API”

being an acronym for Application Program Interface.

16. A storage medium configured with computer data and computer instructions for a method which may be used by a developer to help analyze thread synchronization events, the method comprising the steps of:

receiving the following data for each of a plurality of thread context switches;

switched-in thread identity, switched-out thread identity, switched-out thread state, at least one thread call stack, context switch time of occurrence;

receiving the following data for each of a plurality of kernel thread unblocking synchronization events;

unblocked thread identity, unblocking thread identity, at least one thread call stack, unblocking synchronization event time of occurrence;

determining with the data that a particular thread was synchronization-blocked and subsequently synchronization-unblocked; and

outputting a thread blocking synchronization event analysis based on the data, the thread blocking synchronization analysis identifying an inter-thread synchronization dependency, namely, identifying for two threads which of the threads unblocked the other thread, the thread blocking synchronization analysis containing a link between (i) an unblocking event within a first thread timeline and (ii) a second thread timeline representing a thread which is unblocked by the event.

17. The configured medium of claim 16, wherein the method further comprises providing a mechanism for a user to identify at least one API which is to be treated as a synchronization blocking API during the determining step, “

API”

being an acronym for Application Program Interface.

18. The configured medium of claim 16, wherein the method comprises receiving data for threads which executed in a managed code multi-threaded environment.

19. The configured medium of claim 16, wherein the method further comprises presenting a visualization of thread synchronization events, and the visualization provides at least one of the following:

interactive access to source code responsible for a thread blocking synchronization event, an identification of a thread which holds a synchronization object that is blocked on in a thread blocking synchronization event, thread execution periods based on when a thread is unblocked and when a thread is context switched-in.