70 lines
4.2 KiB
HTML
70 lines
4.2 KiB
HTML
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<meta name="DC.Title" content="API thread safety classifications" />
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<meta name="abstract" content="Before using an API, you should determine if it is safe to call that API in your multithreaded program." />
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<title>API thread safety classifications</title>
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<body id="rzahwapi-apico"><a name="rzahwapi-apico"><!-- --></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">API thread safety classifications</h1>
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<div><p><span>Before using an API, you should determine if
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it is safe to call that API in your multithreaded program.</span></p>
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<div class="section"><div class="p">Each API has a threadsafe classification. The
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three types of threadsafe classifications are as follows:<ul><li>Threadsafe: yes<p>This classification indicates that you can safely call
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the API simultaneously in multiple threads without restrictions. This classification
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also indicates that all functions called by this API are threadsafe. </p>
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</li>
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<li>Threadsafe: conditional<p>This classification indicates that not all functions
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provided by the API are threadsafe. The Usage Notes section of the API provides
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information that relates to thread safety limitations. Many APIs are classified
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conditionally threadsafe because either some underlying system support is
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not threadsafe or the API can call an exit point. For example, many of the
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file system APIs are completely threadsafe when used with files in a threadsafe
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file system. Some conditionally threadsafe APIs might deny access under some
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circumstances. The API usage notes describe the conditions that cause the
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function to deny access. </p>
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</li>
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<li>Threadsafe: no<p>This classification indicates that the API is not threadsafe
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and that the API should not be used in a multithreaded program. While some
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APIs that are not threadsafe might deny access, most APIs that are not threadsafe
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do not. Unlike in CL commands, no diagnostic message is in the job log to
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indicate that an API that is not threadsafe has been called (other than APIs
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that deny access). There are techniques for calling functions that are not
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threadsafe in multithreaded programs. </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 class="relinfo"><strong>Related information</strong><br />
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<div><a href="../apiref/api.htm">Application Programming Interfaces</a></div>
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</div>
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</div>
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