208 lines
5.7 KiB
HTML
208 lines
5.7 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>pthread_getthreadid_np()--Retrieve Unique ID for Calling Thread</title>
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Begin Header Records ========================================== -->
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<!-- NETMG2 SCRIPT A converted by B2H R4.1 (346) (CMS) by HOLTJM at -->
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<!-- RCHVMW2 on 29 Jan 1999 at 10:01:37 -->
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<!--File Edited November 2001 -->
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<!--End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!-- Java sync-link -->
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<script language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>pthread_getthreadid_np()--Retrieve Unique ID for Calling Thread</h2>
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<div class="box" style="width: 50%;">
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<br>
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Syntax:
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<pre>
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#include <pthread.h>
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pthread_id_np_t pthread_getthreadid_np(void);
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</pre>
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Service Program Name: QP0WPTHR<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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Signal Safe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>pthread_getthreadid_np</strong>() function retrieves the unique
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integral identifier that can be used to identify the calling thread in some
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context for application debugging or tracing support.</p>
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<p>In some implementations, the thread ID is equivalent to the pthread_t type.
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In the i5/OS implementation, the pthread_t is an opaque Pthread handle. For
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the ability to identify a thread using a thread ID (unique number), the <strong>
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pthread_getunique_np</strong>() and <strong>pthread_getthreadid_np</strong>()
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interfaces are provided.</p>
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<p>The i5/OS machine implementation of threads provides a 64-bit thread ID.
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The thread ID is returned as a structure containing the high and low order 4
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bytes of the 64-bit ID. This allows applications created by compilers that do
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not yet support 64-bit integral values to effectively use the 64-bit thread
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ID.</p>
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<p>If your code requires the unique integer identifier for the calling thread
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often, or in a loop, the <strong>pthread_getthreadid_np</strong>() function can
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significantly improve performance over the combination of <strong>
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pthread_self</strong>() and <strong>pthread_getunique_np</strong>() calls that
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provide equivalent behavior.</p>
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<p>For example:</p>
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<pre>
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pthread_id_np_t tid;
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tid = pthread_getthreadid_np();
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</pre>
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<p>is significantly faster than these calls, but provides the same
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behavior.</p>
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<pre>
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pthread_id_np_t tid;
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pthread_t self;
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self = pthread_self();
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pthread_getunique_np(&self, &tid);
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</pre>
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<p>As always, if you are calling any function too often, you can improve
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performance by storing the results in a variable or passing to other functions
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that require the results.</p>
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<p><strong>Note:</strong> This function is not portable.</p>
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<br>
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<h3>Authorities and Locks</h3>
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<p>None.</p>
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<br>
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<h3>Return Value</h3>
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<p>The pthread_id_np_t structure identifying the thread</p>
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<br>
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<h3>Error Conditions</h3>
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<p>None.</p>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>pthread.h</strong>> header file. See <a href=
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"rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
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<li><a href="users_28.htm">pthread_self()</a>--Get Pthread Handle<br><br></li>
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<li><a href="users_23.htm">pthread_getunique_np()</a>--Retrieve Unique ID for
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Target Thread</li>
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</ul>
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<br>
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<h3>Example</h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<pre>
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#define _MULTI_THREADED
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#include <pthread.h>
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#include <stdio.h>
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#include "check.h"
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#define NUMTHREADS 3
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void *threadfunc(void *parm)
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{
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printf("Thread 0x%.8x %.8x started\n", pthread_getthreadid_np());
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return NULL;
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}
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int main(int argc, char **argv)
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{
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pthread_t thread[NUMTHREADS];
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int rc=0;
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pthread_id_np_t tid;
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int i=0;
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printf("Enter Testcase - %s\n", argv[0]);
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printf("Main Thread 0x%.8x %.8x\n", pthread_getthreadid_np());
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printf("Create %d threads using joinable attributes\n",
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NUMTHREADS);
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for (i=0; i<NUMTHREADS; ++i) {
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rc = pthread_create(&thread[i], NULL, threadfunc, NULL);
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checkResults("pthread_create()\n", rc);
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pthread_getunique_np(&thread[i], &tid);
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printf("Created thread 0x%.8x %.8x\n", tid);
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}
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printf("Join to threads\n");
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for (i=0; i<NUMTHREADS; ++i) {
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rc = pthread_join(thread[i], NULL);
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checkResults("pthread_join()\n", rc);
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}
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printf("Main completed\n");
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return 0;
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}
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</pre>
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<p><strong>Output:</strong></p>
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<pre>
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Enter Testcase - QP0WTEST/TPGETT0
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Main Thread 0x00000000 0000006c
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Create 3 threads using joinable attributes
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Created thread 0x00000000 0000006d
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Thread 0x00000000 0000006d started
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Created thread 0x00000000 0000006e
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Created thread 0x00000000 0000006f
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Join to threads
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Thread 0x00000000 0000006f started
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Thread 0x00000000 0000006e started
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Main completed
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</pre>
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<br>
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<hr>API introduced: V4R3
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"rzah4mst.htm">Pthread APIs</a> | <a href="aplist.htm">APIs by
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category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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