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I have an error in my error logs that I am trying to figure out but I don't know what to be looking for when it says Child Process.

I understand that its a process done by a parent, but that's an obvious explanation. What does it mean?

Its usage in my error log: child process 1276 still did not exit, sending a SIGKILL

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to find out what is the application which runs as child process, do ps -p 1276 or, in general, ps -p PID –  Victor Sorokin Oct 16 '12 at 18:48
    
ahh, and the child process is the process which was spawned by your process (which seems to be php application) –  Victor Sorokin Oct 16 '12 at 18:49
    
what does this have to do with sql and/or php? –  Marc B Oct 16 '12 at 18:53
    
Marc, I really don't know what causes it, those were two of my guesses. –  Daniel Fein Oct 16 '12 at 19:05
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1 Answer

Very very basically, "processes" are running programs. They're referenced by a number, usually called a "process ID" or "PID". That's the "1276" in the error message.

A "child process" is a process started by some other process (which is the "parent process"). There's really not much more to it than that, in this case.

What this error message means, is that the parent process tried to tell one of its children to end (probably by sending a SIGTERM signal to it) and that didn't work. So the parent process got mean and sent a SIGKILL.

(Some signals can be ignored. SIGTERM is technically one of those; it's a sort of "please exit now" message; a process should clean up and exit upon seeing it. SIGKILL is more like "DIE, foul process! DIEEE!!!", and can't be ignored or even handled, so the receiving process can't clean up or anything -- it just dies. Since it's so potentially messy, it's generally only used for cases where stubborn processes refuse to end politely.)

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+1. Apache 1.x had a similar comment in the code: "die child scum" :) –  Jack Oct 17 '12 at 2:12
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