Re: Kill a process in perl windows and proceed only if it killed the process

[BrowserUk]

in reply to Kill a process in perl windows and proceed only if it killed the process

Will KillProcess return true on success? what this exit code means will that tells me it was a success? How can I check with an exitcode or returnCode and make sure a process actually killed?

• If KillProcess() returns non-zero; the process *will* terminate.

  The process cannot prevent it.

• If it returns zero; it probably means you do not have the privileged to kill it.

  Check $^E for the reason it failed.

• The exitcode parameter to KillProcess() is an input parameter; not an output parameter.

  It is the value that will be returned to any process that calls GetExitProcess() after it has been killed.

• If you absolutely need to know that the process is dead; as opposed to knowing that it will die at some point in the near future:

  Follow the KillProcess() call with a call to the Wait() method.

  When that returns the process is actually dead,

• As stated above, if KillProcess() returns true, the process *will die*; but if you need to know if it was you that killed it:

  Pass an unusual exitcode (eg. not 1 or 0 or -1; say 13579 or your favorite sub 2**16 prime number).

  And then call the GetExitCode() method and compare. Not that you would be able to do anything about it if it wasn't.

There is absolutely no reason to loop!

If you have the appropriate permissions to kill the process; the single call to KillProcess() will kill it. And if you do not; retrying won't help.

Calling the Wait() method will ensure that it has actually died before your program continues; but be aware that if -- for example -- the process had just initiated a synchronous read request -- say a blocking tcp read -- to device or server that was slow, broken or non-existent, then you might have to wait quite some time before the process actually goes away and the Wait() completes. (For example: many tcp timeouts default to 900 seconds; some default DB server timeouts are even longer!)

The bottom line is: for most purposes, simply getting a non-zero return code from KillProcess() is enough to allow you to proceed.

[Anonymous Monk]

I tried the killProcess call followed by wait() call that BrowserUK suggested, but when I tried Win32::Process::Wait it gives me this error message- 'Usage:Win32::Process::Wait(cP, timeout)'
what is 'cP' argument means?

$^E=0;
Win32::Process::KillProcess($pid, 111) or warn $^E;
Win32::Process::Wait(INFINITE);

Thanks,
Peter

[BrowserUk]

what is 'cP' argument means?

You are calling Win32::Process::Wait() as a subroutine; you should be calling it as a method.

[Anonymous Monk]

sorry, I didn't understand.
I get the processids of the applications running on a processing node and I just want to kill it and wait for that process to be killed. I am not creating the process using Win32::Process::Create().