64 lines
4.0 KiB
HTML
64 lines
4.0 KiB
HTML
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<meta name="DC.Title" content="Thread program models" />
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<meta name="abstract" content="There are different models for creating multithread programs." />
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<title>Thread program models</title>
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<body id="rzahwrog-rogco"><a name="rzahwrog-rogco"><!-- --></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">Thread program models</h1>
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<div><p>There are different models for creating multithread programs.</p>
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<p>One of the key differences between <span class="keyword">i5/OS™</span> and
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other platforms is the ability of <span class="keyword">i5/OS</span> to
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support a call-return program model. On other platforms, if one program wants
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to call another, it must start a second process to run the second program,
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or replace the first program with the second. Starting another process to
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call a program is expensive in terms of startup time and system resources.
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To avoid this expense, programmers group commonly used functions into dynamically
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linked libraries (DLLs). Whenever a program needs a service that a DLL provides,
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the program loads the DLL and calls the function that provides the needed
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service. </p>
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<p>Although the <span class="keyword">i5/OS</span> call-return
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program model is supported for multithreaded programs, you are strongly encouraged
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to use service programs or DLLs that run in the caller's activation group.
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If you perform ports of multithreaded programs from other platforms, you will
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naturally employ service programs in their port. </p>
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<p>Although it is not a requirement, all programs
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used in a multithreaded application should be Integrated Language
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Environment<sup>®</sup> (ILE) programs. The use of the original program model (OPM)
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in multithreaded programs requires special considerations. You must evaluate
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the thread safety of existing ILE or OPM programs if multithreaded programs
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call them. </p>
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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="rzahwas4co.htm" title="All programs have at least one thread, referred to as the initial thread. In a program with multiple threads, each thread runs its code independently of the other threads in the program.">Threads on i5/OS</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rzahwopmco.htm" title="Original program model (OPM) programs are not threadsafe.">Threads considerations for OPM language</a></div>
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