Comments on: Process of Confusion

By: Mans

Mans — Sat, 14 Nov 2009 17:04:27 +0000

I sent a patch for a -timelimit option. Let’s see how that goes down.

By: Raymond Tau

Raymond Tau — Fri, 13 Nov 2009 11:31:47 +0000

@Multimedia: Actually, I am not certain if it works in Windows or not. However, I guess it should works for most of *nix machines.

By: Reimar

Reimar — Fri, 13 Nov 2009 01:08:57 +0000

Well, for remote execution you’d have to do even more it seems, you’d have to kill the remote ffmpeg and the local ssh.
Of course the thing is that “normally” killing the shell should also kill ssh and/or ffmpeg, so it might make more sense to investigate how you can ensure that this happens and just kill the shell.

By: Multimedia Mike

Multimedia Mike — Fri, 13 Nov 2009 00:35:20 +0000

It turns out that Python has a module for interfacing to getrlimit() and setrlimit(). Wouldn't you know, the module is only advertised to be available on Unix. Also, per my reading of the documentation, setrlimit() allows restriction on the amount of CPU time a process gets. I'm pretty sure that refers to total CPU running time, not wall clock time. If FFmpeg got into some I/O blocked state, it would likely never hit the timeout. Further, this would be useless (if my theory is correct) in the remote execution case where SSH is just sitting around waiting for the remote process to finish, maybe processing a few NO-OP packets here and there.

By: Mans

Mans — Fri, 13 Nov 2009 00:27:28 +0000

No idea. I can tell you that it must be done on the system running ffmpeg, not the one running the FATE script.

By: Multimedia Mike

Multimedia Mike — Fri, 13 Nov 2009 00:25:45 +0000

@Mans: I’ll check out setrlimit(), especially since I feel I’m running short on other workable ideas. Do you suppose it will work for Windows?

By: Mans

Mans — Thu, 12 Nov 2009 23:25:46 +0000

@Mike: Read about setrlimit(). You can ask the OS to kill a process after it has used a set amount of CPU time. Maybe I should just send a patch…

By: Multimedia Mike

Multimedia Mike — Thu, 12 Nov 2009 22:24:56 +0000

I really don’t like wrapping these test specs in too much shell magic. Every layer introduces possible problems when, e.g., running remotely, running on Windows, or running on some other systems that we haven’t considered yet (BeOS/Haiku?).

By: SvdB

SvdB — Thu, 12 Nov 2009 22:17:06 +0000

Here’s another brainstorm: Ask FFmpeg to print out its own PID (perhaps only when a new option is specified).

You wouldn’t need to modify FFmpeg for that. You could invoke a shell script which starts ffmpeg in the background, and then returns its PID:
./hangaround 30 &
echo $!

By: Multimedia Mike

Multimedia Mike — Thu, 12 Nov 2009 18:21:03 +0000

Here’s another brainstorm: Ask FFmpeg to print out its own PID (perhaps only when a new option is specified). FATE can parse this and use it in the timeout killer. As a bonus, this would reveal the PID of a process running on a remote platform via SSH and facilitate a timeout kill via a separate SSH process.