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25 .Dt PTHREAD_GETCONCURRENCY 3
28 .Nm pthread_getconcurrency ,
29 .Nm pthread_setconcurrency
30 .Nd get or set level of concurrency
36 .Fn pthread_getconcurrency void
38 .Fn pthread_setconcurrency "int new_level"
41 .Fn pthread_setconcurrency
42 function allows an application to inform the threads implementation
43 of its desired concurrency level,
45 The actual level of concurrency provided by the implementation
46 as a result of this function call is unspecified.
49 is zero, it causes the implementation to maintain the concurrency
50 level at its discretion as if
51 .Fn pthread_setconcurrency
54 .Fn pthread_getconcurrency
55 function returns the value set by a previous call to the
56 .Fn pthread_setconcurrency
59 .Fn pthread_setconcurrency
60 function was not previously called, this function returns zero to
61 indicate that the implementation is maintaining the concurrency
63 When an application calls
64 .Fn pthread_setconcurrency ,
65 it is informing the implementation of its desired concurrency
67 The implementation uses this as a hint, not a requirement.
70 .Fn pthread_setconcurrency
71 function returns zero.
72 Otherwise, an error number is returned
73 to indicate the error.
75 .Fn pthread_getconcurrency
76 function always returns the concurrency level set by a previous
78 .Fn pthread_setconcurrency .
80 .Fn pthread_setconcurrency
81 function has never been called,
82 .Fn pthread_getconcurrency
86 .Fn pthread_setconcurrency
87 function will fail if:
90 The value specified by
94 The value specified by
96 would cause a system resource to be exceeded.
99 Use of these functions changes the state of the underlying
100 concurrency upon which the application depends.
101 Library developers are advised to not use the
102 .Fn pthread_getconcurrency
104 .Fn pthread_setconcurrency
105 functions since their use may conflict with an application's
106 use of these functions.
109 .Fn pthread_getconcurrency
111 .Fn pthread_setconcurrency