The spawn() API provides a mechanism to allow you to start a debugging session before actually calling the multithreaded program to be debugged.
Setting the QIBM_CHILD_JOB_SNDINQMSG environment variable to 1 controls this capability. Refer to the usage notes for the spawn() API in the System API Reference, for details about the use of this environment variable.
An example SPAWN command is available for your use and modification as part of i5/OS™ option 7, the i5/OS Example Tools Library, QUSRTOOL. Member TP0ZINFO in the file QATTINFO in the QUSRTOOL library contains information about how to create the SPAWN CL command.
You can also simplify the process of starting a job that runs the multithreaded program and the debugging session by creating a command (such as the SPAWN command) that performs the necessary steps. The steps are as follows:
- Signing on to a display station session
- Starting a job to run the multithreaded program
- Using the Start Service Job (STRSRVJOB) command to service the job running the multithreaded program
- Calling the Start Debug (STRDBG) command, adding programs to debug, and setting breakpoints
- Notifying the servicing job when the thread hits a breakpoint so that it stops the thread
- Stopping all threads with the debugger support
- Issuing valid debug commands from the debug screen that is displayed
- Resuming the thread that hit the breakpoint and then all other threads
- Repeating the above cycle until debugging is complete
- Calling the End Debug (ENDDBG) command
You can find additional information about thread debugging capabilities in the following topics:
