Computer-implemented method and system for automatically invoking a predetermined debugger command at a desired location of a single thread of a program

• US 6,978,444 B1
• Filed: 08/01/2000
• Issued: 12/20/2005
• Est. Priority Date: 08/01/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ur, Shmuol, Ziv, Avi, Farchi, Eitan
• Primary Examiner(s): COURTENAY III, ST JOHN
• Application Number:
  US09/630,411
• Time in Patent Office: 1,967 Days
• Field of Search: 717124-135, 717/149, 717/151, 717/158, 714/38
• US Class Current: 717/129
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program

Abstract

A computer-implemented method and system for automatically invoking a predetermined debugger command at a desired location of a single thread of a program containing at least one thread. At the desired location of the program thread, there is embedded a utility which reads a trace file in which the predetermined debugger command has been previously embedded. Upon re-running the program, the trace file is read and upon reaching the predetermined debugger command, the debugger attaches itself to the running process and executes the process from its current program counter. The debugger is invoked only if there is a discrepancy between successive runs of the program.

Claims

1. A computer-implemented method for automatically invoking at least one predetermined debugger command at a desired location of a single thread of a program containing at least one thread for debugging said single thread at the desired location, said method comprising:

(a) embedding within said single thread at said desired location thereof a utility that is configured for creating a trace file if the trace file does not exist;

(b) running the program during a first pass so as to create the trace file and write a traced value of a specified variable at the location in the program where the utility is embedded; and

(c) running the program during a second pass so that on reaching said desired location, the utility is invoked for reading said trace file and invoking said at least one predetermined debugger command that has been previously embedded in the trace file in place of the traced value of said variable.

2. The method according to claim 1, wherein the debugger attaches itself to a predetermined debugger command, which halts execution of the program and shows a state of the program at that time.

3. The method according to claim 1, wherein the program is multi-threaded and there is included the further operation of:

(c) providing a mechanism for rerunning the program with identical interleaving as far as invocation of the utility is concerned.

4. The method according to claim 3, further including the operation of creating the mechanism automatically upon invocation of the utility.

5. The method according to claim 3, wherein the program includes multiple threads, each of which prints an invariant associated with a status of the program, said invariant having a value that remains constant regardless of the interleaving.

6. A computer-implemented method for automatically invoking at least one predetermined debugger command at a desired location of a specific thread of a program containing at least one thread, said’

method comprising;

(a) embedding within the specific thread of the program at said desired location thereof a utility which;

i) creates a trace file if it does not exist;

ii) if a compare flag is set to a first value, writes a traced value of at least one variable thereto at a desired location of the program; and

iii) if the compare flag is set to a second value compares a current value of the least one variable with a respective line in the trace file and if they are different invokes a debugger so as to execute a debugger command embedded in the trace file in place of the traced value; and

(b) running the program so that on reaching said desired location, the utility is invoked for reading a modified trace file readable by the program wherein at least one traced value is replaced or augmented by said debugger command.

7. The method according to claim 6, wherein the at least one predetermined debugger command halts execution of the program and shows the state of the program at that time.

8. The method according to claim 6, wherein the program is multi-threaded and there is included the further operation of:

(c) providing a mechanism for rerunning the program with identical interleaving as far as invocation of the utility is concerned.

9. The method according to claim 8, including the further operation of creating the mechanism automatically upon invocation of the utility.

10. The method according to claim 8, wherein the program includes multiple threads, each of which prints an invariant associated with a status of the program, said invariant having a value that remains constant regardless of the interleaving.

11. The method according to claim 10, wherein operation (a)(ii) includes:

i) attempting a bipartite matching between the threads and the traces such that every thread has a trace which contains what the thread printed, and

ii) stopping the program if said bipartite matching is not possible.

12. The method according to claim 10, further including providing a mechanism for manually or automatically bypassing step (a) (ii) so that traces are created in respect of only a subset of the threads.

13. The method according to claim 10, wherein operation (b) includes:

i) reading the modified trace file in respect of local views of the threads only, so as to avoid a need for synchronizing break-points in said multiple threads.

14. The method according to claim 6, wherein the program includes multiple threads and operation (a)(ii) includes:

i) creating for each thread a respective trace file having a name which is uniquely defined by a name of the respective thread;

thereby allowing debugger commands embedded in any of the trace files to be executed during running of a respective one of the threads.

15. The method according to claim 14, further including the operation of automatically naming said trace files according to a predetermined execution-independent naming scheme.

16. The method according to claim 15, wherein said naming scheme includes:

i) assigning a root name to a root thread,

ii) maintaining a thread-bound index structure for holding, for each thread, a corresponding index counter which is atomically incremented upon thread creation, and

iii) upon creation of a child thread assigning a name including a prefix indicative of a name of a respective parent thread and a suffix indicative of an index counter of the respective parent thread.

17. The method according to claim 6, further including setting the compare flag to the second value on exit from the program.

18. A computer program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform a method for automatically invoking at least one predetermined debugger command at a desired location of a single thread of a program containing at least one thread for debugging said single thread at the desired location, said method comprising:

(a) embedding within said program thread at said desired location thereof a utility that is configured for creating a trace file if the trace file does not exist;

(b) running the program during a first pass so as to create the trace file and write a traced value of a specified variable at the location in the program where the utility is embedded; and

(c) running the program during a second pass so that on reaching said desired location, the utility is invoked for reading said trace file and invoking at least one predetermined debugger command that has been previously embedded in the trace file in place of the traced value of said variable.

19. A computer program product comprising a computer useable medium having computer readable program code embodied therein for automatically invoking at least one predetermined debugger command at a desired location of a single thread of a program containing at least one thread for debugging said single thread at the desired location, said computer program product comprising:

computer readable program code for causing the computer to embed within said program thread at said desired location thereof a utility that is configured for creating a trace file if the trace file does not exist and which otherwise reads the trace file;

computer readable program code responsive to a flag being set to a first value for causing the computer to write to the trace file a traced value of a specified variable at the location in the program where the utility is embedded; and

computer readable program code responsive to the flag being set to a second value for causing the computer to invoke the utility on reaching said desired location for reading said trace file and invoking at least one predetermined debugger command that has been previously embedded in the trace file in place of the traced value of said variable.

20. The computer program product according to claim 19, further including setting the flag to the second value on exit from the program.

21. A computer program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform a method for automatically invoking at least one predetermined debugger command at a desired location of a specific thread of a program containing at least one thread, said method comprising:

(a) embedding within the specific thread of the program at said desired location thereof a utility which;

i) if a compare flag is set to a first value, creates the trace file if it does not exist and writes to the trace file a traced value of at least one variable thereto at a desired location of the program; and

ii) if a compare flag is set to a second value, compares a current value of the least one variable with a respective line in the trace file and if they are different invokes a debugger so as to execute a debugger command embedded in the trace file in place of the traced value; and

(b) running the program so that on reaching said desired location, the utility is invoked for reading a modified trace file readable by the program wherein at least one traced value is replaced or augmented by said debugger command.

22. The computer program storage device according to claim 21, further including setting the compare flag to the second value on exit from the program.

23. A computer program product comprising a computer useable medium having computer readable program code embodied therein for automatically invoking at least one predetermined debugger command at a desired location of a specific thread of a program containing at least one thread, said computer program product comprising:

computer readable program code for causing the computer to embed within the specific thread of the program at said desired location thereof a utility which reads a trace file in which said at least one predetermined debugger command has been previously embedded;

computer readable program code for causing the computer to create the trace file if the trace file does not exist, and being responsive to a compare flag being set to a first value to write a traced value of at least one variable thereto at a desired location of the program; and

computer readable program code responsive to the compare flag being set to a second value for causing the computer to compare a current value of the least one variable with a respective line in the trace file, and if they are different to invoke a debugger so as to execute a debugger command embedded in the trace file in place of the traced value; and

computer readable program code for causing the computer to run the program so that on reaching said desired location, the utility is invoked for reading a modified trace file readable by the program wherein at least one traced value is replaced or augmented by said debugger command.

38. The computer program product according to claim 23, further including setting the compare flag to the second value on exit from the program.

24. A computer program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform a method steps for automatically invoking at least one predetermined debugger command at a desired location of a specific thread of a program containing at least one thread, said method comprising:

(a) if the trace file does not exist, creating the trace file;

(b) if a compare flag is set to a first value writing to the trace file a traced value of at least one variable thereto at a desired location of the program; and

(c) a compare flag is set to a second value, comparing a current value of said at least one variable with a respective line in the trace file and if they are different invoking a debugger so as to execute a debugger command embedded in the trace file in place of the traced value.

39. The computer program storage device according to claim 24, further including setting the compare flag to the second value on exit from the program.

25. A computer program product comprising a computer useable medium having computer readable program code embodied therein for automatically invoking at least one predetermined debugger command at a desired location of a specific thread of a program containing at least one thread, said computer program product comprising:

computer readable program code for causing the computer to create the trace file if the trace file does not exist;

computer readable program code responsive to a compare flag being set to a first value for causing the computer to write a traced value of at least one variable thereto at a desired location of the program; and

computer readable program code responsive to the compare flag being set to a second value for causing the computer to compare a current value of the at least one variable with a respective line in the trace file, and if they are different to invoke a debugger so as to execute a debugger command embedded in the trace file in place of the traced value.

40. The computer program product according to claim 25, further including setting the compare flag to the second value on exit from the program.

26. A computer-implemented system for automatically invoking at least one predetermined debugger command at a desired location of a single thread of a program containing at least one thread for debugging said single thread at the desired location, said system comprising:

a code modifier for embedding within said single thread at said desired location thereof a utility that is configured for creating a trace file if the trace file does not exist and which is responsive to a compare flag being set to a first value for writing to the trace file a traced value of at least one variable thereto at a desired location of the program; and

a processor responsive to the compare flag being set to a second value for invoking said utility for reading said trace file during running of the program upon reaching said desired location and invoking said at least one predetermined debugger command that has been previously embedded in the trace file in place of the traced value of said variable.

27. The system according to claim 26, further including:

a file management system coupled to the processor and responsive to said utility for creating the trace file if it does not exist;

a file modifier coupled to the file management system and responsive to a compare flag being set to a first value for writing to the trace file a traced value of at least one variable at said desired location of the program; and

a comparator coupled to the processor and responsive to the compare flag being set to a second value for comparing a current value of the least one variable with a respective line in the trace file and if they are different construing the respective line in the trace file as a debugger command and invoking a debugger so as to execute the debugger command.

28. The system according to claim 26, wherein the debugger is adapted to attach itself to a predetermined debugger command, which halts execution of the program and shows a state of the program at that time.

29. The system according to claim 26, wherein the program is multi-threaded and there is further included a replay mechanism coupled to the processor for rerunning the program with identical interleaving as far as invocation of the utility is concerned.

41. The system according to claim 26, further including setting the compare flag to the second value on exit from the program.

30. A computer-implemented system for automatically invoking at least one predetermined debugger command at a desired location of a specific thread of a program containing at least one thread, said system comprising:

a code modifier for embedding within said single thread at said desired location thereof a utility which reads a trace file in which said at least one predetermined debugger command has been previously embedded;

a file management system coupled to the processor and responsive to said utility for creating the trace file if it does not exist;

a file modifier coupled to the file management system and responsive to a compare flag being set to a first value for writing to the trace file a traced value of at least one variable at said desired location of the program;

a processor for running the program so that on reaching said desired location, the utility is invoked for reading a modified trace file readable by the program wherein at least one traced value is replaced or augmented by said debugger command; and

a comparator coupled to the processor and responsive to a compare flag being set to a second value for comparing a current value of the least one variable with a respective line in the trace file and if they are different construing the respective line in the trace file as a debugger command and invoking a debugger so as to execute the debugger command.

31. The system according to claim 30, wherein the program is multi-threaded and there is further included a replay mechanism coupled to the processor for rerunning the program with identical interleaving as far as invocation of the utility is concerned.

32. The system according to claim 30, wherein the program includes multiple threads and the file management system is adapted to create for each thread a respective trace file having a name which is uniquely defined by a name of the respective thread, thereby allowing debugger commands embedded in any of the trace files to be executed during a respective one of the threads.

33. The system according to claim 32, wherein the file management system is responsive to a predetermined execution-independent naming scheme for automatically naming said trace files.

34. The system according to claim 33, wherein the file management system includes:

an assignment unit for assigning a root name to a root thread, and

a thread-bound index structure for holding for each thread a corresponding index counter which is atomically incremented upon thread creation;

said assignment unit being responsive to creation of a child thread for assigning a name including a prefix indicative of a name of a respective parent thread and a suffix indicative of an index counter of the respective parent thread.

35. The system according to claim 34, wherein the assignment unit is responsive to no consistent naming being possible for attempting a bipartite matching between the threads and the traces such that every thread has a trace which contains what the thread printed, and for stopping the program so as to avoid executing debugger commands embedded in each of the traces at the wrong time if said bipartite matching is not possible.

36. The system according to claim 30, further including a bypass mechanism coupled to the file modifier for allowing creation of the trace file to be manually or automatically bypassed so that traces are created in respect of only a subset of the threads.

37. The system according to claim 30, wherein the processor is adapted to read the modified trace file in respect of local views of the threads only, so as to avoid a need for synchronizing break-points in said multiple threads.

42. The system according to claim 30, further including setting the compare flag to the second value, on exit from the program.