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pthread_getconcurrency(3c) [opensolaris man page]

pthread_getconcurrency(3C)				   Standard C Library Functions 				pthread_getconcurrency(3C)

NAME
pthread_getconcurrency, pthread_setconcurrency - get or set level of concurrency SYNOPSIS
cc -mt [ flag... ] file... -lpthread [ library... ] #include <pthread.h> int pthread_getconcurrency(void); int pthread_setconcurrency(int new_level); DESCRIPTION
Unbound threads in a process may or may not be required to be simultaneously active. By default, the threads implementation ensures that a sufficient number of threads are active so that the process can continue to make progress. While this conserves system resources, it may not produce the most effective level of concurrency. The pthread_setconcurrency() function allows an application to inform the threads implementation of its desired concurrency level, new_level. The actual level of concurrency provided by the implementation as a result of this function call is unspecified. If new_level is 0, it causes the implementation to maintain the concurrency level at its discretion as if pthread_setconcurrency() was never called. The pthread_getconcurrency() function returns the value set by a previous call to the pthread_setconcurrency() function. If the pthread_setconcurrency() function was not previously called, this function returns 0 to indicate that the implementation is maintaining the concurrency level. When an application calls pthread_setconcurrency() it is informing the implementation of its desired concurrency level. The implementation uses this as a hint, not a requirement. If an implementation does not support multiplexing of user threads on top of several kernel scheduled entities, the pthread_setconcur- rency() and pthread_getconcurrency() functions will be provided for source code compatibility but they will have no effect when called. To maintain the function semantics, the new_level parameter will be saved when pthread_setconcurrency() is called so that a subsequent call to pthread_getconcurrency() returns the same value. RETURN VALUES
If successful, the pthread_setconcurrency() function returns 0. Otherwise, an error number is returned to indicate the error. The pthread_getconcurrency() function always returns the concurrency level set by a previous call to pthread_setconcurrency(). If the pthread_setconcurrency() function has never been called, pthread_getconcurrency() returns 0. ERRORS
The pthread_setconcurrency() function will fail if: EINVAL The value specified by new_level is negative. EAGAIN The value specific by new_level would cause a system resource to be exceeded. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
pthread_create(3C), pthread_attr_init(3C), attributes(5), standards(5) SunOS 5.11 23 Mar 2005 pthread_getconcurrency(3C)

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pthread_getconcurrency(3T)												pthread_getconcurrency(3T)

NAME
pthread_getconcurrency(), pthread_setconcurrency() - get or set the concurrency level of unbound threads SYNOPSIS
PARAMETERS
new_level New concurrency level for the unbound threads in the calling process. DESCRIPTION
The unbound threads in a process may or may not be required to be simultaneously active. By default, the threads implementation ensures that a sufficient number of threads are active so that the process can continue to make progress. While this conserves system resources, it may not produce the most effective level of concurrency. The function allows an application to inform the threads implementation of its desired concurrency level, new_level. The actual level of concurrency provided by the system as a result of this function call is unspeci- fied. If new_level is zero, it will cause the implementation to maintain the concurrency level at its discretion as if were never called. The function returns the value set by a previous call to If the function was not previously called, this function returns zero to indicate that the system is maintaining the concurrency level. Note: When an application calls it is informing the implementation of its desired concurrency level. The implementation will use this as a hint, not a requirement. A call to immediately after a call to may return a different concurrency level specified in If the system does not support the multiplexing of user threads on top of several kernel-scheduled entities, the functions and functions will be provided for source code compatibility, but they shall have no effect when called. To maintain the function semantics, the new_level parameter will be saved when is called so that a subsequent call to will return the same value. RETURN VALUE
If successful, returns zero. Otherwise, an error number is returned to indicate the error (the variable is not set). The function always returns the concurrency level set by a previous call to If the function has never been called, shall return zero. ERRORS
If any of the following occur, the function shall return the corresponding error number. [EINVAL] The value specified by new_level is invalid. [EAGAIN] The value specified by new_level would cause a system resource to be exceeded. APPLICATION USAGE
Use of these functions changes the state of the underlying concurrency level upon which the application depends. Library developers are advised to not use the and functions as their use may conflict with an applications use of these functions. AUTHOR
and were developed by X/Open. SEE ALSO
pthread_num_processors_np(3T), pthread_processor_bind_np(3T), pthread_processor_id_np(3T). STANDARDS CONFORMANCE
Pthread Library pthread_getconcurrency(3T)
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