Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!thunder.mcrcim.mcgill.edu!mouse
From: mouse@thunder.mcrcim.mcgill.edu (der Mouse)
Newsgroups: comp.unix.wizards
Subject: Re: How do you catch a signal without terminating the process ?
Keywords: SIgnal, Process
Message-ID: <1991Jun7.145102.24125@thunder.mcrcim.mcgill.edu>
Date: 7 Jun 91 14:51:02 GMT
References: <1991Jun5.215644.20581@csl.dl.nec.com>
Organization: McGill Research Centre for Intelligent Machines
Lines: 40

In article <1991Jun5.215644.20581@csl.dl.nec.com>, manohar@csl.dl.nec.com (mun o her) writes:

> Server1 = Original Server ( something similar to inetd)
> Server2 = Effective current Server.

> Assume that we are writing a program to implement a concurrent
> server.  Assume that Server1 spawns a Server2 when the client wants
> the connection and Server1 goes back to the accept state.  When the
> Server2 terminates as a result of the termination of client.  The
> Server1 must be notified of its death so that it can execute wait( to
> get rid of zombie of Server2).  If Signal Handler is used to catch
> SIGCHLD the accept (Server1) is interrupted

This is normal, or at least not abnormal, depending on your system.

> and the PROBLEM is that the 'whole program' dies.

This is a bug in the server.

> The intention is to resume accept state of Server1.  The question is
> How do you PREVENT Server1 from [dying] and resume accept state.

Fix the bug.

There is nothing about SIGCHLD that should kill off the server.  I
assume you have set up a handler for SIGCHLD; the handler should wait
for the dead child.  (The details of this differ from system to system,
and you don't say what your system is, so I can't elaborate.)

Most likely the code assumes that any error return from accept() should
be fatal.  This is the bug; if accept() returns with errno indicating
EINTR, you should simply go back and retry the accept().

If that's not it I'd need more information.

					der Mouse

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