wait(2)

[Marcin 'Qrczak' Kowalczyk]

Thu, 26 Jul 2001 16:44:57 +0200, George Russell <ger@tzi.de> pisze:

> Is there a way in Glasgow Haskell to get a thread to wait on a
> child process in the same way as the Posix function wait(), and
> get the termination status of the child?

There is no easy way: all Haskell's thread run in the same process
and wait() blocks the whole process.

The only (or the only portable) way is to call wait() with WNOHANG
repeatedly in a thread and threadDelay for a short period of time
between calls.

This is what OCaml runtime does. It provides waiting for a process
as a threading primitive. It accounts for waiting in its select()
loop in the scheduler.

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