proc-nice.xml

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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 
       whereas positive values have a lower priority.
      </para>
      <para>
       For Windows the <parameter>priority</parameter> parameter has the 
       following meaning:
      </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 current <emphasis>process</emphasis>
    priority, even if PHP was compiled using thread safety.
   </para>
  </note>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><function>pcntl_setpriority</function></member>
  </simplelist>
 </refsect1>
</refentry>
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