Hello, i am looking for different ways to pause and resume programmatically a particular process via his process ID under Windows XP.
http://www.codeproject.com/KB/threads/pausep.aspx does it with SuspendThread / ResumeThread but warns about multithreaded programs and deadlocks problem.
PsSuspend looks ok : http://technet.microsoft.com/en-us/sysinternals/bb897540.aspx I wonder if it does anything special about deadlocks or use another method ?
Prefered languages : C++ / Python
I think there is a good reason why there is no SuspendProcess() function in Windows. Having such a function opens the door for an unstable system. You shall not suspend a process unless you created that process yourself. If you wrote that process yourself, you could use an event (see ::SetEvent() etc. in MSDN) or another kind of messaging to trigger a pause command in the process.
If you "debug the debugger" (for instance, using logger.exe to trace all API calls made by windbg.exe), it appears that the debugger uses SuspendThread()/ResumeThread() to suspend all of the threads in the process being debugged.
PsSuspend may use a different way of suspending processes (I'm not sure), but it is still possible to hang other processes: if the process you're suspending is holding a shared synchronization object that is needed by another process, you may block that other process from making any progress. If both programs are well-written, they should recover when you resume the one that you suspended, but not all programs are well-written. And if this causes your program that is doing the suspending to hang, then you have a deadlock.
I tested http://www.codeproject.com/KB/threads/pausep.aspx on few softwares:
it works fine.
PsSuspend and Pausep are two valid options.