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problem implementing fork

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Top Forums Programming problem implementing fork
# 8  
Old 10-11-2009
A couple of things come to mnd....
  1. I'd use something other than SIGALRM to signal the parent. Perhaps SIGCHLD or SIGUSR1
  2. Forking gives the parent the opportunity to do something useful if the kid hangs. For instance, if the I/O subsystem were to be unable to complete an i/o and fail to return an error on a Solaris (or any system using DMA for I/O) , the kid will be unkillable and hang. This is because you might remove the process memory, reallocate it to another process only to have the DMA device complete the physical i/o. It might be useful to tell someone about the i/o issue via a timeout mechanism.
  3. Is forking all that expensive in a Linux system? Most everything except for the LWP stuff will be created with either model. The forking model makes expansion of the code to handle multiple tasks saner..

sorry about the late reply...
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LEARN ABOUT CENTOS

uuidd

UUIDD(8)						       System Administration							  UUIDD(8)

NAME

       uuidd - UUID generation daemon

SYNOPSIS

       uuidd [options]

DESCRIPTION

       The  uuidd  daemon is used by the UUID library to generate universally unique identifiers (UUIDs), especially time-based UUIDs, in a secure
       and guaranteed-unique fashion, even in the face of large numbers of threads running on different CPUs trying to grab UUIDs.

OPTIONS

       -d, --debug
	      Run uuidd in debugging mode.  This prevents uuidd from running as a daemon.

       -h, --help
	      Display help screen and exit.

       -k, --kill
	      If currently a uuidd daemon is running, kill it.

       -n, --uuids number
	      When issuing a test request to a running uuidd, request a bulk response of number UUIDs.

       -p, --pid path
	      Specify the pathname where the pid file should be written.  By default, the pid file is written to /var/uuidd/uuidd.pid.

       -P, --no-pid
	      Do not create pid file.

       -F, --no-fork
	      Do not daemonize using double-fork.

       -S, --socket-activation
	      Do not create the socket and instead expect it to be provided by the calling process.  Implies --no-fork and --no-pid.  As  of  this
	      writing, this option is supposed to be used only with systemd.  This option must be enabled with a configure option.

       -q, --quiet
	      Suppress some failure messages.

       -r, --random
	      Test uuidd by trying to connect to a running uuidd daemon and request it to return a random-based UUID.

       -s, --socket path
	      Specify  the  pathname used for the unix-domain socket used by uuidd.  By default, the pathname used is /var/uuidd/request.  This is
	      primarily for debugging purposes, since the pathname is hard-coded in the libuuid library.

       -T, --timeout timeout
	      Specify a timeout for uuidd.  If specified, then uuidd will exit after timeout seconds of inactivity.

       -t, --time
	      Test uuidd by trying to connect to a running uuidd daemon and request it to return a time-based UUID.

       -V, --version
	      Output version information and exit.

EXAMPLE

       Start up a daemon, print 42 random keys, and then stop the daemon.

	      uuidd -p /tmp/uuidd.pid -s /tmp/uuidd.socket
	      uuidd -d -r -n 42 -s /tmp/uuidd.socket
	      uuidd -d -k -s /tmp/uuidd.socket

AUTHOR

       The uuidd daemon was written by Theodore Ts'o <tytso@mit.edu>.

AVAILABILITY

       The uuidd daemon is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

SEE ALSO

       uuid(3), uuidgen(1)

util-linux							     June 2011								  UUIDD(8)