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Top Forums Programming How to implement SIGKILL and SIGTERM and print a message? Post 302144795 by porter on Friday 9th of November 2007 08:01:14 PM
Old 11-09-2007
1. Both sigaction and signal install signal handlers,

(a) don't use both in the same program,
(b) sigaction is the posix one, use that.
(c) With sigaction you don't need to reinstall the signal handler.

2. atexit installs another callback function, so when the program exits politely, through a call to exit you code will get called so you can tidy up.

3. only set flags in the signal handlers, don't do 'work'.

4. you have done sigfillset but done nothing with the sigset_t, you need to call sigprocmask to block or unblock those signals.

5. to ignore a signal, you can

(a) either use SIG_IGN as the callback
(b) or simply block it so it is never delivered to your program.
(c) or get it to call an empty signal handler function

6. compile with maximum warnings, if you are using gcc use "-Wall -Werror", that would have caught your "atexit".

7. And as mentioned, you can't catch SIGKILL, the kernel will just evaporate your process.
 

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Net::Server::Fork(3)					User Contributed Perl Documentation				      Net::Server::Fork(3)

NAME
Net::Server::Fork - Net::Server personality SYNOPSIS
use base qw(Net::Server::Fork); sub process_request { #...code... } __PACKAGE__->run(); DESCRIPTION
Please read the pod on Net::Server first. This module is a personality, or extension, or sub class, of the Net::Server module. This personality binds to one or more ports and then waits for a client connection. When a connection is received, the server forks a child. The child handles the request and then closes. With the exception of parent/child signaling, this module will work (with basic functionality) on Win32 systems. ARGUMENTS
check_for_dead Number of seconds to wait before looking for dead children. This only takes place if the maximum number of child processes (max_servers) has been reached. Default is 60 seconds. max_servers The maximum number of children to fork. The server will not accept connections until there are free children. Default is 256 children. max_dequeue The maximum number of dequeue processes to start. If a value of zero or undef is given, no dequeue processes will be started. The number of running dequeue processes will be checked by the check_for_dead variable. check_for_dequeue Seconds to wait before forking off a dequeue process. It is intended to use the dequeue process to take care of items such as mail queues. If a value of undef is given, no dequeue processes will be started. CONFIGURATION FILE
See Net::Server. PROCESS FLOW
Process flow follows Net::Server until the post_accept phase. At this point a child is forked. The parent is immediately able to wait for another request. The child handles the request and then exits. HOOKS
The Fork server has the following hooks in addition to the hooks provided by the Net::Server base class. See Net::Server "$self->pre_accept_hook()" This hook occurs just before the accept is called. "$self->post_accept_hook()" This hook occurs in the child after the accept and fork. "$self->run_dequeue()" This hook only gets called in conjunction with the check_for_dequeue setting. HOT DEPLOY
Since version 2.000, the Fork server has accepted the TTIN and TTOU signals. When a TTIN is received, the max_servers is increased by 1. If a TTOU signal is received the max_servers is decreased by 1. This allows for adjusting the number of handling processes without having to restart the server. AUTHOR
Paul Seamons <paul@seamons.com> Rob Brown <bbb@cpan.org> SEE ALSO
Please see also Net::Server::INET, Net::Server::PreFork, Net::Server::MultiType, Net::Server::SIG Net::Server::Single perl v5.18.2 2013-01-09 Net::Server::Fork(3)
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