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pcntl_wait / pcntl_waitpid: Document the rusage parameter (fixes #861) #4917

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pcntl_wait / pcntl_waitpid: Document the rusage parameter (fixes #861) #4917

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pcntl_wait / pcntl_waitpid: Document the rusage parameter (fixes #861)
AllenJB Oct 11, 2025
fd20c6a
pcntl_wait / pcntl_waitpid: Document the rusage parameter (fixes #861…
AllenJB Oct 11, 2025
55c86d4
pcntl_wait / pcntl_waitpid: Document the rusage parameter (fixes #861…
AllenJB Oct 28, 2025
cb6baa4
pcntl_wait / pcntl_waitpid: Document the rusage parameter (fixes #861…
AllenJB Oct 28, 2025
b9cb0c2
pcntl_wait / pcntl_waitpid: Document the rusage parameter (fixes #861…
AllenJB Oct 28, 2025
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69 changes: 69 additions & 0 deletions reference/pcntl/functions/pcntl-wait.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,16 @@
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>resource_usage</parameter></term>
<listitem>
<para>
Stores the resource usage information for the child that exited as an
associative <type>array</type>. For information on the contents see
<function>getrusage</function>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
Expand All @@ -99,12 +109,71 @@
</para>
</refsect1>

<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>pcntl_wait</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
function checkChildren(bool $wait): void
{
$flags = ($wait ? 0 : WNOHANG);
$deadPid = pcntl_wait($status, $flags, $rusage);
if ($deadPid === -1) {
$errNo = pcntl_get_last_error();
$errMsg = pcntl_strerror($errNo);
print "PARENT pcntl_wait FAILED ({$deadPid}): {$errMsg}\n";
} elseif ($deadPid === 0) {
print "PARENT pcntl_wait: No exited children.\n";
} else {
print "PARENT pcntl_wait: Child PID {$deadPid} exited with status: "
. pcntl_wexitstatus($status) ."\n";
var_dump($rusage);
}
}
$parentPid = getmypid();
$forkedPid = pcntl_fork();
if ($forkedPid == -1) {
die('Could not fork');
} else if ($forkedPid) {
// Parent process
print "PARENT {$parentPid} has forked {$forkedPid}\n";
print "PARENT is checking for exited children\n";
checkChildren(false);
// Prevents children remaining as a "zombie process"
print "PARENT is waiting for a child to exit\n";
checkChildren(true);
print "PARENT is checking for exited children\n";
checkChildren(false);
print "PARENT is exiting\n";
} else {
// Child process
$pid = getmypid();
print "CHILD {$pid} is sleeping\n";
sleep(10);
print "CHILD is exiting\n";
exit(7);
}
]]>
</programlisting>
</example>
</para>
</refsect1>

<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>pcntl_fork</function></member>
<member><function>pcntl_signal</function></member>
<member><function>pcntl_waitpid</function></member>
<member><function>pcntl_wifexited</function></member>
<member><function>pcntl_wifstopped</function></member>
<member><function>pcntl_wifsignaled</function></member>
Expand Down
69 changes: 69 additions & 0 deletions reference/pcntl/functions/pcntl-waitpid.xml
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -130,6 +130,16 @@
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>resource_usage</parameter></term>
<listitem>
<para>
Stores the resource usage information for the child that exited as an
associative <type>array</type>. For information on the contents see
<function>getrusage</function>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
Expand All @@ -143,12 +153,71 @@
</para>
</refsect1>

<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
Comment on lines +161 to +163
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@Girgias Girgias Nov 4, 2025

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Useless wrapping para tag

<title><function>pcntl_waitpid</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
function checkChild(int $pid, bool $wait): void
{
$flags = ($wait ? 0 : WNOHANG);
$deadPid = pcntl_waitpid($pid, $status, $flags, $rusage);
if ($deadPid === -1) {
$errNo = pcntl_get_last_error();
$errMsg = pcntl_strerror($errNo);
print "PARENT pcntl_waitpid FAILED ({$deadPid}): {$errMsg}\n";
} elseif ($deadPid === 0) {
print "PARENT pcntl_waitpid: No exited children.\n";
} else {
print "PARENT pcntl_waitpid: Child PID {$deadPid} exited with status: "
. pcntl_wexitstatus($status) ."\n";
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@TimWolla TimWolla Oct 28, 2025

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The documentation for wexitstatus says:

This function is only useful if pcntl_wifexited() returned true.

So, is a wifexited call missing here? Looking more carefully at the example, it uses quite a few functions from the pcntl extension. It might make sense to include it in https://www.php.net/manual/en/pcntl.example.php instead.

var_dump($rusage);
}
}

$parentPid = getmypid();
$forkedPid = pcntl_fork();
if ($forkedPid == -1) {
die('Could not fork');
} else if ($forkedPid) {
// Parent process
print "PARENT {$parentPid} has forked {$forkedPid}\n";

print "PARENT is checking for exited children\n";
checkChild($forkedPid, false);

// Prevents children remaining as a "zombie process"
print "PARENT is waiting for a child to exit\n";
checkChild($forkedPid, true);

print "PARENT is checking for exited children\n";
checkChild($forkedPid, false);

print "PARENT is exiting\n";
} else {
// Child process
$pid = getmypid();
print "CHILD {$pid} is sleeping\n";
sleep(10);
print "CHILD is exiting\n";
exit(7);
}
]]>
</programlisting>
</example>
</para>
</refsect1>

<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>pcntl_fork</function></member>
<member><function>pcntl_signal</function></member>
<member><function>pcntl_wait</function></member>
<member><function>pcntl_wifexited</function></member>
<member><function>pcntl_wifstopped</function></member>
<member><function>pcntl_wifsignaled</function></member>
Expand Down