Re: How to asynchronisly get notified of a child exit

You probably could whip up a state machine implementing this with POE and POE::Wheel::Run fairly easily. The background tasks would be run in separate processes with P::W::Run while the main process' session runs the others (waiting until the background wheels send it an event that they're complete).

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Comment on Re: How to asynchronisly get notified of a child exit

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Re^2: How to asynchronisly get notified of a child exit by Mostly Harmless (Initiate) on Jul 07, 2005 at 18:23 UTC
That's interesting. I tried to read up POE couple of times, but found the learning curve to be steep :-( Can POE pre-empt a session ? I thought something like yield() has to be called from the code block for the POE kernel to look at events. If a code blocks for quite sometime, then POE kernel wouldn't be aware about other session events - am I right ? Or am I talking non-sense ? :-) Also, wouldn't I need to change my entire existing codebase to make it POE enabled ? I have a new module that spawns and controls processes, where I can use POE. I do not know how much of work it'd involve to use POE for the rest of the code. thanks !	[reply]
Re^3: How to asynchronisly get notified of a child exit by Fletch (Bishop) on Jul 07, 2005 at 18:49 UTC
If you use POE::Wheel::Run then you can run a sub in a separate forked process. That sub could run your existing `f2()` and then print something to STDOUT (say `f2 done`). The parent session in the parent process has something watching for output from that child wheel which sends itself a "f2done" event (and upon receiving that event it starts whatever was waiting for `f2` to complete). It wouldn't be seamless, but it should be doable. -- We're looking for people in ATL	[reply] [d/l] [select]
Re^4: How to asynchronisly get notified of a child exit by Mostly Harmless (Initiate) on Jul 08, 2005 at 05:44 UTC
My existing routine prints everything to it's stdout, which is redirected to a log file before fork(). But I think I can use a different filehandle for communication. I'll dig up the doc. to see what POE does if a session blocks forever or a child exits abruptly. I think it'd also mean the application cannot use CHLD handlers, as it'd interfere with POE's.	[reply]