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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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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. -F, --no-fork Do not daemonize using a double-fork. -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, --no-pid Do not create a pid file. -p, --pid path Specify the pathname where the pid file should be written. By default, the pid file is written to /run/uuidd/uuidd.pid. -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-activation Do not create a socket but instead expect it to be provided by the calling process. This implies --no-fork and --no-pid. This option is intended to be used only with systemd(1). It needs to be enabled with a configure option. -s, --socket path Make uuidd use this pathname for the unix-domain socket. By default, the pathname used is /run/uuidd/request. This option is pri- marily for debugging purposes, since the pathname is hard-coded in the libuuid library. -T, --timeout number Make uuidd exit after number 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. -h, --help Display help screen 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>. SEE ALSO
uuid(3), uuidgen(1) AVAILABILITY
The uuidd daemon is part of the util-linux package and is available from the Linux Kernel Archive <https://www.kernel.org/pub/linux/utils /util-linux/>. util-linux July 2014 UUIDD(8)

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