102 lines
5.9 KiB
HTML
102 lines
5.9 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="CL commands and thread safety" />
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<meta name="abstract" content="The Integrated Language Environment (ILE) CL run time and compiler-generated code are threadsafe. Original program model (OPM) CL programs are not threadsafe." />
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<meta name="description" content="The Integrated Language Environment (ILE) CL run time and compiler-generated code are threadsafe. Original program model (OPM) CL programs are not threadsafe." />
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<meta name="DC.Relation" scheme="URI" content="rzahwsafco.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzahwnonco.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Identifier" content="rzahwclc-clcco" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>CL commands and thread safety</title>
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</head>
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<body id="rzahwclc-clcco"><a name="rzahwclc-clcco"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">CL commands and thread safety</h1>
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<div><p>The Integrated
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Language Environment<sup>®</sup> (ILE) CL run time and compiler-generated code are
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threadsafe. Original program model (OPM) CL programs are not threadsafe.</p>
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<div class="section"><p>For any ILE CL code that is compiled before Version 4 Release
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3 or any OPM CL code, the CL run time sends a CPD000B diagnostic
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message and continues to run with unpredictable results. This might or might
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not be threadsafe, depending on the underlying code.</p>
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</div>
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<div class="section"><p>Command analyzer is threadsafe. For a given command, if the threadsafe
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attribute (THDSAFE) is *NO and the multithreaded job action attribute (MLTTHDACN)
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is set to *NORUN or *MSG, the command analyzer does one of the following when
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such a command is called in a job capable of multithreaded operations: </p>
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<ul><li>If MLTTHDACN is set to *NORUN in a multithreaded job, command analyzer
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sends a CPD000D diagnostic message, and the command does not run. A CPF0001
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escape message then follows the CPD000D diagnostic message.</li>
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<li>If MLTTHDACN is set to *MSG in a multithreaded job, command analyzer sends
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a CPD000D diagnostic message, and the program continues to run with unpredictable
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results.</li>
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<li>If the job is capable of running multiple threads but is not actually
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multithreaded, command analyzer allows commands that are not threadsafe to
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run without interference.</li>
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</ul>
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<p>If MLTTHDACN is set to *RUN, the command analyzer does not send a
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diagnostic message and allows the command to run. The results of this are
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unpredictable. Also, MLTTHDACN only applies to comments whose THDSAFE value
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is *NO. To determine the THDSAFE and MLTTHDACN values for a command, use <span class="cmdname">Display
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Command (DSPCMD)</span>.</p>
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</div>
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<div class="section"><p>The MLTTHDACN value of some commands is set to *SYSVAL. In this
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case, command analyzer uses the QMLTTHDACN system value to decide how to
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process the command. </p>
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</div>
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<div class="section"><p>To display the setting of this value on <span class="keyword">i5/OS™</span>: </p>
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</div>
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<div class="section"><p><span class="cmdname">DSPSYSVAL</span> SYSVAL(QMLTTHDACN) </p>
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</div>
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<div class="section"><p>To change the setting of this value on <span class="keyword">i5/OS</span>: </p>
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</div>
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<div class="section"><p><span class="cmdname">CHGSYSVAL</span> SYSVAL(QMLTTHDACN) VALUE(x) </p>
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</div>
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<div class="section"><div class="p">Sample output from <span class="cmdname">DSPSYSVAL</span>: <pre>
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Display System Value
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System value . . . . . : QMLTTHDACN
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Description . . . . . : Multithreaded job action
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Multithreaded job
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action . . . . . . . : 2
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1=Perform the function that is not
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threadsafe without sending a message
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2=Perform the function that is not
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threadsafe and send an informational
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message
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3=Do not perform the function that is
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not threadsafe </pre>
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</div>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahwsafco.htm" title="A function is threadsafe if you can start it simultaneously in multiple threads within the same process. A function is threadsafe if and only if all the functions it calls are also threadsafe.">Thread safety</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzahwmulco.htm" title="If you are going to write multithreaded applications or server applications for i5/OS, you should be familiar with several techniques.">Multithreaded programming techniques</a></div>
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<div><a href="rzahwnonco.htm" title="Your multithreaded application at times requires access to functions or system services that are not thread safe. There are few completely safe alternatives for calling these functions.">Function calls that are not thread safe</a></div>
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</div>
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</div>
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</body>
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</html>
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