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Re: Pass data to a subprocess

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Date Wed, 01 Aug 2012 16:32:04 +0200
From Laszlo Nagy <gandalf@shopzeus.com>
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Subject Re: Pass data to a subprocess
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>>> things get more tricky, because I can't use queues and pipes to
>>> communicate with a running process that it's noit my child, correct?
>>>
>> Yes, I think that is correct.
> I don't understand why detaching a child process on Linux/Unix would
> make IPC stop working.  Can somebody explain?
>
It is implemented with shared memory. I think (although I'm not 100% 
sure) that shared memory is created *and freed up* (shm_unlink() system 
call) by the parent process. It makes sense, because the child processes 
will surely die with the parent. If you detach a child process, then it 
won't be killed with its original parent. But the shared memory will be 
freed by the original parent process anyway. I suspect that the child 
that has mapped that shared memory segment will try to access a freed up 
resource, do a segfault or something similar.

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Thread

Re: Pass data to a subprocess Laszlo Nagy <gandalf@shopzeus.com> - 2012-08-01 10:19 +0200
  Re: Pass data to a subprocess Roy Smith <roy@panix.com> - 2012-08-01 06:59 -0400
    Re: Pass data to a subprocess Laszlo Nagy <gandalf@shopzeus.com> - 2012-08-01 13:07 +0200
    Re: Pass data to a subprocess Laszlo Nagy <gandalf@shopzeus.com> - 2012-08-01 13:26 +0200
    Re: Pass data to a subprocess andrea crotti <andrea.crotti.0@gmail.com> - 2012-08-01 14:25 +0100
    Re: Pass data to a subprocess Roy Smith <roy@panix.com> - 2012-08-01 15:07 -0400
  Re: Pass data to a subprocess Grant Edwards <invalid@invalid.invalid> - 2012-08-01 14:16 +0000
    Re: Pass data to a subprocess Laszlo Nagy <gandalf@shopzeus.com> - 2012-08-01 16:32 +0200
      Re: Pass data to a subprocess Grant Edwards <invalid@invalid.invalid> - 2012-08-01 19:48 +0000
        Re: Pass data to a subprocess Laszlo Nagy <gandalf@shopzeus.com> - 2012-08-02 08:10 +0200
          Re: Pass data to a subprocess Grant Edwards <invalid@invalid.invalid> - 2012-08-02 14:29 +0000
        Re: Pass data to a subprocess Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-02 13:21 -0400
    Re: Pass data to a subprocess Laszlo Nagy <gandalf@shopzeus.com> - 2012-08-01 16:42 +0200
    Re: Pass data to a subprocess andrea crotti <andrea.crotti.0@gmail.com> - 2012-08-01 16:24 +0100

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