58 lines
2.5 KiB
HTML
58 lines
2.5 KiB
HTML
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>Mutexes return EDEADLK when re-locked by owner</title>
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<h2>Mutexes return EDEADLK when re-locked by owner</h2>
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<p>Some threads implementations return the EDEADLK error when a mutex attempts
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to relock a mutex that it already owns. The POSIX standard specifies that the
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results are undefined when a mutex is re-locked by the owner. The Single UNIX
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Specification addresses these issues by providing a new mutex attribute called
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<em>type</em>.</p>
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<p>The iSeries threads support takes the same implementation route that the
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Single UNIX Specification suggests, and it also causes the thread to deadlock
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when it attempts to re-lock a normal (non-recursive) mutex. Because many users
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of Pthreads do not check return codes from functions, the deadlock protects
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applications from corrupted data that might result if they attempt to relock an
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already held mutex, then unlock the mutex as if the lock was successful.</p>
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<p>See <a href="users_53.htm#370578">pthread_mutexattr_gettype()--Get Mutex
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Type Attribute</a> and <a href="users_58.htm#370784">
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pthread_mutexattr_settype()--Set Mutex Type Attribute</a> if you need
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error-checking mutexes for your application.</p>
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<a href="rzah4mst.htm">Pthread APIs</a> |
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<a href="aplist.htm">APIs by category</a></td>
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