<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html lang="en-us" xml:lang="en-us"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="security" content="public" /> <meta name="Robots" content="index,follow" /> <meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' /> <meta name="DC.Type" content="concept" /> <meta name="DC.Title" content="Function calls that are not thread safe" /> <meta name="abstract" content="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." /> <meta name="description" content="Your multithreaded application at times requires access to functions or system services that are not thread safe. 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Licensed Materials Property of IBM --> <!-- US Government Users Restricted Rights --> <!-- Use, duplication or disclosure restricted by --> <!-- GSA ADP Schedule Contract with IBM Corp. --> <link rel="stylesheet" type="text/css" href="./ibmdita.css" /> <link rel="stylesheet" type="text/css" href="./ic.css" /> <title>Function calls that are not thread safe</title> </head> <body id="rzahwnon-nonco"><a name="rzahwnon-nonco"><!-- --></a> <!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script> <h1 class="topictitle1">Function calls that are not thread safe</h1> <div><p>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.</p> <p>To illustrate the alternatives, consider the example of a program that calls API <span class="apiname">foo()</span>. Because function <span class="apiname">foo()</span> is listed as not being thread safe, you need to find a safe way to call it. Two common options are using a global mutual exclusion (mutex) or using a separate job to run the function that is not thread safe.</p> </div> <div> <ul class="ullinks"> <li class="ulchildlink"><strong><a href="rzahwgloco.htm">Use global mutexes to run functions that are not threadsafe</a></strong><br /> One alternative you should consider when you need to call a function that is not threadsafe is using a global mutual exclusion (mutex) to run these functions.</li> <li class="ulchildlink"><strong><a href="rzahwjobco.htm">Use separate jobs to run functions that are not threadsafe</a></strong><br /> There are several threadsafe mechanisms to submit a new job to complete the processing you need.</li> </ul> <div class="familylinks"> <div class="parentlink"><strong>Parent topic:</strong> <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> </div> <div class="relconcepts"><strong>Related concepts</strong><br /> <div><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> <div><a href="rzahwsynco.htm" title="When you create code that is threadsafe but still benefits from sharing data or resources between threads, the most important aspect of programming becomes the ability to synchronize threads.">Synchronization techniques among threads</a></div> <div><a href="rzahwoneco.htm" title="At times, you might want to defer the initialization of resources until a thread requires them. However, your application might require that multiple threads use a certain resource, which requires you to initialize the resource only once in a threadsafe way.">One-time initialization and thread safety</a></div> <div><a href="rzahwcomco.htm" title="Several programming errors often occur when writing multithreaded applications.">Common multithreaded programming errors</a></div> </div> <div class="relref"><strong>Related reference</strong><br /> <div><a href="rzahwclcco.htm" title="The Integrated Language Environment (ILE) CL run time and compiler-generated code are threadsafe. Original program model (OPM) CL programs are not threadsafe.">CL commands and thread safety</a></div> <div><a href="rzahwileco.htm" title="You can create an Integrated Language Environment (ILE) COBOL or ILE RPG module that will run safely in a multithreaded environment by serializing access to the module.">Threads considerations for ILE COBOL and RPG language</a></div> </div> </div> </body> </html>