php-doc-en/reference/exec/functions/proc-nice.xml
2021-06-06 18:03:03 +01:00

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<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.proc-nice" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>proc_nice</refname>
<refpurpose>Change the priority of the current process</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>bool</type><methodname>proc_nice</methodname>
<methodparam><type>int</type><parameter>priority</parameter></methodparam>
</methodsynopsis>
<para>
<function>proc_nice</function> changes the priority of the current
process by the amount specified in <parameter>priority</parameter>. A
positive <parameter>priority</parameter> will lower the priority of the
current process, whereas a negative <parameter>priority</parameter>
will raise the priority.
</para>
<para>
<function>proc_nice</function> is not related to
<function>proc_open</function> and its associated functions in any way.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>priority</parameter></term>
<listitem>
<para>
The new priority value, the value of this may differ on platforms.
</para>
<para>
On Unix, a low value, such as <literal>-20</literal> means high priority
wheras a positive value have a lower priority.
</para>
<para>
For Windows the <parameter>priority</parameter> parameter have the
following meanings:
</para>
<informaltable>
<tgroup cols="3">
<thead>
<row>
<entry valign="top">Priority class</entry>
<entry valign="top">Possible values</entry>
</row>
</thead>
<tbody>
<row>
<entry valign="top">High priority</entry>
<entry valign="top">
<parameter>priority</parameter> <literal>&lt; -9</literal>
</entry>
</row>
<row>
<entry valign="top">Above normal priority</entry>
<entry valign="top">
<parameter>priority</parameter> <literal>&lt; -4</literal>
</entry>
</row>
<row>
<entry valign="top">Normal priority</entry>
<entry valign="top">
<parameter>priority</parameter> <literal>&lt; 5</literal> &amp;
<parameter>priority</parameter> <literal>&gt; -5</literal>
</entry>
</row>
<row>
<entry valign="top">Below normal priority</entry>
<entry valign="top">
<parameter>priority</parameter> <literal>&gt; 5</literal>
</entry>
</row>
<row>
<entry valign="top">Idle priority</entry>
<entry valign="top">
<parameter>priority</parameter> <literal>&gt; 9</literal>
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
&return.success;
If an error occurs, like the user lacks permission to change the priority,
an error of level <constant>E_WARNING</constant> is also generated.
</para>
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>7.2.0</entry>
<entry>
This function is now available on Windows.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>Using <function>proc_nice</function> to set the process priority to high</title>
<programlisting role="php">
<![CDATA[
<?php
// Highest priority
proc_nice(-20);
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="notes">
&reftitle.notes;
<note>
<title>Availability</title>
<para>
<function>proc_nice</function> will only exist if your system has 'nice'
capabilities. 'nice' conforms to: SVr4, SVID EXT, AT&amp;T, X/OPEN, BSD
4.3.
</para>
</note>
<note>
<title>Windows only</title>
<para>
<function>proc_nice</function> will change the <emphasis>current</emphasis> process
priority, even if PHP was compiled using thread safety.
</para>
</note>
</refsect1>
</refentry>
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