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[Caml-list] Client/Server socket communication
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Date: -- (:)
From: Alessandro Baretta <alex@b...>
Subject: Re: [Caml-list] Client/Server socket communication


Tim Freeman wrote:
>>Why "server <defunct>" is occurred.
>>What do I have to do to correct <defunct> ?
> 
> 
> This is a Unix thing, not an OCAML thing.  The child will be defunct
> to hold the exit status so it can be reported to the parent when the
> parent waits for it, or until the parent exits.
> 
> One workaround is to wait for the child process when you expect it to exit.
> 
> Another workaround is to fork twice, so the original process is the
> parent of a temporary process, and the temporary process is the parent
> of the process you really wanted to create.  The temporary process
> exits immediately and the original parent waits for it immediately.
> This leaves no defunct processes.
> 

A third workaround might be to use SIGCHLD handler to 
asynchronously call wait or waitpid, but there might be 
issues with the non-reentrance-with-respect-to-signals of 
the libc. I doubt O'Caml could be any more signal-safe than 
libc.

A fourth workaround is to use O'Caml threads, which do not 
require the kernel to instantiate a new process, so no new 
pid is allocated.

Alex

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