77 lines
4.7 KiB
HTML
77 lines
4.7 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 http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Job-scoped resources and thread safety" />
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<meta name="abstract" content="Many system and application resources are available only within a defined job. When writing a multithreaded application or service, you must evaluate your use of job-scoped resources. The use of these resources must not conflict with or negatively affect other threads in the process." />
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<meta name="description" content="Many system and application resources are available only within a defined job. When writing a multithreaded application or service, you must evaluate your use of job-scoped resources. The use of these resources must not conflict with or negatively affect other threads in the process." />
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<meta name="DC.Relation" scheme="URI" content="rzahwsafco.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.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rzahwjre-jreco" />
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<meta name="DC.Language" content="en-us" />
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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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<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>Job-scoped resources and thread safety</title>
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</head>
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<body id="rzahwjre-jreco"><a name="rzahwjre-jreco"><!-- --></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">Job-scoped resources and thread safety</h1>
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<div><p>Many system and application resources are available only within
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a defined job. When writing a multithreaded application or service, you must
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evaluate your use of job-scoped resources. The use of these resources must
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not conflict with or negatively affect other threads in the process.</p>
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<div class="section"><p>Some resources (open database files, for example) are scoped to
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the activation group. For the purposes of this discussion, resources that
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are scoped to the activation group must be treated with the same considerations
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as job-scoped resources. All of the threads that use the activation group
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use them.</p>
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</div>
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<div class="section"><p>Your application can use appropriate synchronization techniques
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if threads in your application modify these resources while other threads
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are using them, and you need to ensure a consistent view of the resources
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between your threads.</p>
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</div>
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<div class="section"><div class="p">Some of the common job-scoped or activation group-scoped resources
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are as follows:<ul><li>Heap, static, and global storage:<p>The most commonly shared resource.
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For more information, see the section about storage usage.</p>
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</li>
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<li>Open files:<p>After you open a file, threads in a process can directly
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share integrated file system file and database files by passing the file handle
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pointer or file descriptor number to another thread. The working directory
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is always scoped to the process.</p>
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</li>
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<li>Locales:<p>The locale of an application is an activation group resource.
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All threads share the locale. Changing the locale affects other threads with
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regard to collating sequences or other locale information.</p>
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</li>
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<li>Coded character set identifier:<p>Changing the coded character set identifier
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(CCSID) of a job affects the current data translation or representation of
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all threads in that job.</p>
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</li>
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<li>Environment variables:<p>Your application commonly uses environment
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variables for configuration and optional behavior. All the threads in the
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job share them.</p>
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</li>
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</ul>
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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>
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</body>
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</html>
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