[26570] in Perl-Users-Digest
Perl-Users Digest, Issue: 8707 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri Nov 25 21:05:17 2005
Date: Fri, 25 Nov 2005 18:05:03 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Fri, 25 Nov 2005 Volume: 10 Number: 8707
Today's topics:
Re: potential problem with fork() xhoster@gmail.com
Re: potential problem with fork() <tadmc@augustmail.com>
Re: potential problem with fork() <nospam-abuse@ilyaz.org>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: 25 Nov 2005 21:32:56 GMT
From: xhoster@gmail.com
Subject: Re: potential problem with fork()
Message-Id: <20051125163256.083$D9@newsreader.com>
bsder <snort_sam@yahoo.com> wrote:
> Hi,
>
> I m not sure whether the following Perl code is correct with fork().
>
> while (1) {
> if (open( FILE, "< $books" ) {
Syntax error, unbalanced parens. Also, you wouldn't you want to do
something more intelligent in case the file can't be opened?
> if (!defined($kidpid = fork())) {
> die "cannot fork: $!";
> }
> elsif ($kidpid == 0) { # child
> child_func();
child_func() had better never return, or else you are making a fork-bomb.
> }
> else # parent.
> sleep(1);
> }
> }
>
> Can anyone please give comment and suggestion of improving it?
Without knowing what it is supposed to do?
Xho
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------------------------------
Date: Fri, 25 Nov 2005 11:09:51 -0600
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: potential problem with fork()
Message-Id: <slrndoehav.4a4.tadmc@magna.augustmail.com>
bsder <snort_sam@yahoo.com> wrote:
> I m not sure whether the following Perl code is correct with fork().
>
> while (1) {
> if (open( FILE, "< $books" ) {
> if (!defined($kidpid = fork())) {
> die "cannot fork: $!";
> }
Control can never get here if the fork() failed, so...
> elsif ($kidpid == 0) { # child
... you don't need an elsif, just an if would do.
> child_func();
> }
Control can never get here in the child process, so ...
> else # parent.
... you don't need an else at all.
(and if you did need an else, you would need an opening curly bracket)
> sleep(1);
> }
> }
>
> Can anyone please give comment and suggestion of improving it?
# untested
while (1) {
if (open( FILE, "< $books" ) {
die "cannot fork: $!" unless defined($kidpid = fork());
if ($kidpid == 0) { # child
child_func();
}
# parent
sleep(1);
}
}
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Fri, 25 Nov 2005 22:30:21 +0000 (UTC)
From: Ilya Zakharevich <nospam-abuse@ilyaz.org>
Subject: Re: potential problem with fork()
Message-Id: <dm839t$n2o$1@agate.berkeley.edu>
[A complimentary Cc of this posting was sent to
Tad McClellan
<tadmc@augustmail.com>], who wrote in article <slrndoehav.4a4.tadmc@magna.augustmail.com>:
> # untested
> while (1) {
> if (open( FILE, "< $books" ) {
> die "cannot fork: $!" unless defined($kidpid = fork());
>
> if ($kidpid == 0) { # child
> child_func();
> }
> # parent
How should I guess looking on this code that child_func() never
returns? IMO, one should at least move exit() out of child_func()
into the main loop to make the intent clear...
> sleep(1);
> }
> }
Hope this helps,
Ilya
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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End of Perl-Users Digest V10 Issue 8707
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