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Bug #52992 No SIGCHLD signal received
Submitted: 2010-10-05 14:55 UTC Modified: -
Avg. Score:4.1 ± 1.0
Reproduced:3 of 3 (100.0%)
Same Version:1 (33.3%)
Same OS:1 (33.3%)
From: dverspui at hotpop dot com Assigned:
Status: Open Package: PCNTL related
PHP Version: 5.3.3 OS: CentOS 5.5
Private report: No CVE-ID: None
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 [2010-10-05 14:55 UTC] dverspui at hotpop dot com
The included CLI test script forks a child process and should terminate when the child process finishes after two seconds with the message that SIGCHLD signal (17) was received. This works as expected on my Fedora system with PHP 5.3.3-1 installed, but the process never receives SIGCHLD on my CentOS system with identically built PHP 5.3.3-1.

The configure line for the CentOS system is the one below, the Fedora one is the same except for some differences in paths but not options:
'./configure' '--build=x86_64-redhat-linux-gnu' '--host=x86_64-redhat-linux-gnu' '--target=x86_64-redhat-linux-gnu' '--program-prefix=' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib64' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/usr/com' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--cache-file=../config.cache' '--with-libdir=lib64' '--with-config-file-path=/etc' '--with-config-file-scan-dir=/etc/php.d' '--disable-debug' '--with-pic' '--disable-rpath' '--without-pear' '--with-bz2' '--with-exec-dir=/usr/bin' '--with-freetype-dir=/usr' '--with-png-dir=/usr' '--with-xpm-dir=/usr' '--enable-gd-native-ttf' '--with-t1lib=/usr' '--without-gdbm' '--with-gettext' '--with-gmp' '--with-iconv' '--with-jpeg-dir=/usr' '--with-openssl' '--with-pcre-regex=/usr' '--with-zlib' '--with-layout=GNU' '--enable-exif' '--enable-ftp' '--enable-magic-quotes' '--enable-sockets' '--enable-sysvsem' '--enable-sysvshm' '--enable-sysvmsg' '--with-kerberos' '--enable-ucd-snmp-hack' '--enable-shmop' '--enable-calendar' '--with-libxml-dir=/usr' '--enable-xml' '--with-apxs2=/usr/sbin/apxs' '--without-mysql' '--without-gd' '--disable-dom' '--disable-dba' '--without-unixODBC' '--disable-pdo' '--disable-xmlreader' '--disable-xmlwriter' '--without-sqlite' '--without-sqlite3' '--disable-phar' '--disable-fileinfo' '--disable-json' '--without-pspell' '--disable-wddx' '--without-curl' '--disable-posix' '--disable-sysvmsg' '--disable-sysvshm' '--disable-sysvsem'  

I rebuilt the CentOS PHP with explicit option --disable-sigchld but that didn't help, it is the default after all.

Test script:
if (($pid = pcntl_fork()) === 0)
else if ($pid !== -1)
  $signals = array(SIGINT, SIGCHLD);
  pcntl_sigprocmask(SIG_BLOCK, $signals, $prevSignals);
  $signal = pcntl_sigwaitinfo($signals, $info);
  echo "received signal ${signal}\n";

Expected result:
> php test.php
received signal 17

Actual result:
> php test.php
process runs forever until SIGINT is received (CTRL+C), the child process is defunct after two seconds


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 [2021-10-08 16:12 UTC] thewitness at cacti dot net
It looks like all the good signals are being masked.  This includes:


I read somewhere where the MySQL/MariaDB library itself may be blocking the signal propagation.  It would be nice if someone from the Dev team could follow up on this.

 [2021-10-08 16:14 UTC] thewitness at cacti dot net
Disregard the previous comment.  Wrong bug ;)
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