CSC/ECE 506 Spring 2013/3a bs - Revision history

Bvumman: /* Joins */

2013-02-21T03:02:28Z

Joins

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	==== Joins ====		==== Joins ====
	~~-------------------~~
	A join is performed when one wants to wait for a thread to finish. A thread calling routine may launch multiple threads and then wait for them to finish to get the results.		A join is performed when one wants to wait for a thread to finish. A thread calling routine may launch multiple threads and then wait for them to finish to get the results.

Bvumman: /* Joins */

2013-02-21T03:02:15Z

Joins

← Older revision		Revision as of 03:02, 21 February 2013
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	==== Joins ====		==== Joins ====
			-------------------
	A join is performed when one wants to wait for a thread to finish. A thread calling routine may launch multiple threads and then wait for them to finish to get the results.		A join is performed when one wants to wait for a thread to finish. A thread calling routine may launch multiple threads and then wait for them to finish to get the results.

Bvumman: /* Joins */

2013-02-21T02:59:49Z

Joins

← Older revision		Revision as of 02:59, 21 February 2013
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	A join is performed when one wants to wait for a thread to finish. A thread calling routine may launch multiple threads and then wait for them to finish to get the results.		A join is performed when one wants to wait for a thread to finish. A thread calling routine may launch multiple threads and then wait for them to finish to get the results.

	'''• ''pthread_join(pthread_t thread,void **value_ptr):''''' This function determines if a thread has completed before starting another task. The argument,thread refers to the thread id and value_ptr refers to the value passed from pthread_exit. This function suspends the execution of the calling thread until the target thread terminates, unless the target thread has already terminated.On return from a successful pthread_join() call with a non-NULL value_ptr argument, the value passed to pthread_exit() by the terminating thread shall be made available in the location referenced by value_ptr. When a pthread_join() returns successfully, the target thread has been terminated. The results of multiple simultaneous calls to pthread_join() specifying the same target thread are undefined. If the thread calling pthread_join() is canceled, then the target thread shall not be detached.		'''• ''pthread_join(pthread_t thread,void **value_ptr):''''' This function determines if a thread has completed before starting another task. The argument,thread refers to the thread id and value_ptr refers to the value passed from pthread_exit. This function suspends the execution of the calling thread until the target thread terminates, unless the target thread has already terminated.On return from a successful pthread_join() call with a non-NULL value_ptr argument, the value passed to [http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_exit.3.html pthread_exit()] by the terminating thread shall be made available in the location referenced by value_ptr. When a pthread_join() returns successfully, the target thread has been terminated. The results of multiple simultaneous calls to pthread_join() specifying the same target thread are undefined. If the thread calling pthread_join() is canceled, then the target thread shall not be detached.

	Return Value: The function returns zero on success; otherwise, the error number is returned to indicate the error.		Return Value: The function returns zero on success; otherwise, the error number is returned to indicate the error.

Bvumman: /* Avoiding Deadlockhttp://www2.chrishardick.com:1099/Notes/Computing/C/pthreads/mutexes.html */

2013-02-21T02:58:36Z

Avoiding Deadlockhttp://www2.chrishardick.com:1099/Notes/Computing/C/pthreads/mutexes.html

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	'''3. Chaining:'''		'''3. Chaining:'''

	• Traversing linked lists and other tree data structures		• Traversing [http://en.wikipedia.org/wiki/Linked_list linked lists] and other [http://en.wikipedia.org/wiki/Tree_(data_structure)tree data structures].

	• A locking hierarchy is to be created, like Lock1, Lock2, Lock3, Unlock1, Lock4.		• A locking hierarchy is to be created, like Lock1, Lock2, Lock3, Unlock1, Lock4.

Bvumman: /* Destroying the Barrier */

2013-02-21T02:56:45Z

Destroying the Barrier

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	===== Destroying the Barrier =====		===== Destroying the Barrier =====

	'''• ''int pthread_barrier_destroy(pthread_barrier_t *barrier):'''''This function is used to destroy the barrier passed by the barrier attribute and also releases any resources used by the barrier. A destroyed barrier can be reused when reinitialized by another call to ~~[[Initialising the Barrier]]~~pthread_barrier_init().The destroyed barrier is set to an invalid value. The results are undefined if pthread_barrier_destroy() is called when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.		'''• ''int pthread_barrier_destroy(pthread_barrier_t *barrier):'''''This function is used to destroy the barrier passed by the barrier attribute and also releases any resources used by the barrier. A destroyed barrier can be reused when reinitialized by another call to pthread_barrier_init().The destroyed barrier is set to an invalid value. The results are undefined if pthread_barrier_destroy() is called when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.

	Return Value: Upon successful completion, the functions returns zero; otherwise, an error number is returned to indicate the error.		Return Value: Upon successful completion, the functions returns zero; otherwise, an error number is returned to indicate the error.

Bvumman: /* Destroying the Barrier */

2013-02-21T02:56:12Z

Destroying the Barrier

← Older revision		Revision as of 02:56, 21 February 2013
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	===== Destroying the Barrier =====		===== Destroying the Barrier =====

	'''• ''int pthread_barrier_destroy(pthread_barrier_t *barrier):'''''This function is used to destroy the barrier passed by the barrier attribute and also releases any resources used by the barrier. A destroyed barrier can be reused when reinitialized by another call to [[~~Abc~~]]pthread_barrier_init().The destroyed barrier is set to an invalid value. The results are undefined if pthread_barrier_destroy() is called when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.		'''• ''int pthread_barrier_destroy(pthread_barrier_t *barrier):'''''This function is used to destroy the barrier passed by the barrier attribute and also releases any resources used by the barrier. A destroyed barrier can be reused when reinitialized by another call to [[Initialising the Barrier]]pthread_barrier_init().The destroyed barrier is set to an invalid value. The results are undefined if pthread_barrier_destroy() is called when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.

	Return Value: Upon successful completion, the functions returns zero; otherwise, an error number is returned to indicate the error.		Return Value: Upon successful completion, the functions returns zero; otherwise, an error number is returned to indicate the error.

Bvumman: /* Destroying the Barrier */

2013-02-21T02:53:17Z

Destroying the Barrier

← Older revision		Revision as of 02:53, 21 February 2013
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	===== Destroying the Barrier =====		===== Destroying the Barrier =====

	'''• ''int pthread_barrier_destroy(pthread_barrier_t *barrier):'''''This function is used to destroy the barrier passed by the barrier attribute and also releases any resources used by the barrier. A destroyed barrier can be reused when reinitialized by another call to pthread_barrier_init().The destroyed barrier is set to an invalid value. The results are undefined if pthread_barrier_destroy() is called when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.		'''• ''int pthread_barrier_destroy(pthread_barrier_t *barrier):'''''This function is used to destroy the barrier passed by the barrier attribute and also releases any resources used by the barrier. A destroyed barrier can be reused when reinitialized by another call to [[Abc]]pthread_barrier_init().The destroyed barrier is set to an invalid value. The results are undefined if pthread_barrier_destroy() is called when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.

	Return Value: Upon successful completion, the functions returns zero; otherwise, an error number is returned to indicate the error.		Return Value: Upon successful completion, the functions returns zero; otherwise, an error number is returned to indicate the error.

Bvumman: /* Barrier Wait */

2013-02-21T02:52:33Z

Barrier Wait

← Older revision		Revision as of 02:52, 21 February 2013
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	When the required number of threads have arrived at the barrier during the execution of a signal handler, it marks the completion of barrier wait.If a signal is delivered to a thread blocked on a barrier, upon return from the signal handler the thread resumes waiting at the barrier if the barrier wait has not completed; otherwise, the thread continues as normal from the completed barrier wait. Until the thread in the signal handler returns from it, it is unspecified whether other threads may proceed past the barrier once they have all reached it.A thread that has blocked on a barrier does not prevent any unblocked thread that is eligible to use the same processing resources from eventually making forward progress in its execution. Eligibility for processing resources is determined by the scheduling policy.		When the required number of threads have arrived at the barrier during the execution of a signal handler, it marks the completion of barrier wait.If a signal is delivered to a thread blocked on a barrier, upon return from the signal handler the thread resumes waiting at the barrier if the barrier wait has not completed; otherwise, the thread continues as normal from the completed barrier wait. Until the thread in the signal handler returns from it, it is unspecified whether other threads may proceed past the barrier once they have all reached it.A thread that has blocked on a barrier does not prevent any unblocked thread that is eligible to use the same processing resources from eventually making forward progress in its execution. Eligibility for processing resources is determined by the scheduling policy.

	Return Value: Upon successful completion, the function shall return PTHREAD_BARRIER_SERIAL_THREAD for an arbitrary thread synchronized at the barrier and zero for each of the other threads. Otherwise, an error number shall be returned to indicate the error.		Return Value: Upon successful completion, the function shall return [http://www.lindevdoc.org/doku/libc:pthread_barrier_serial_thread PTHREAD_BARRIER_SERIAL_THREAD] for an arbitrary thread synchronized at the barrier and zero for each of the other threads. Otherwise, an error number shall be returned to indicate the error.

	===== Destroying the Barrier =====		===== Destroying the Barrier =====

Bvumman: /* Avoiding Deadlockhttp://www2.chrishardick.com:1099/Notes/Computing/C/pthreads/mutexes.html */

2013-02-21T02:51:26Z

Avoiding Deadlockhttp://www2.chrishardick.com:1099/Notes/Computing/C/pthreads/mutexes.html

← Older revision		Revision as of 02:51, 21 February 2013
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	'''1. Establish a locking hierarchy:'''		'''1. Establish a locking hierarchy:'''

	• A hierarchy needs to be established to hold multiple locks		• A hierarchy needs to be established to hold multiple [http://en.wikipedia.org/wiki/Lock_(computer_science) locks].

	• A rule could be established such that in order to lock mutex_a and mutex_b, mutex_a must be locked before mutex_b.		• A rule could be established such that in order to lock mutex_a and mutex_b, mutex_a must be locked before mutex_b.

Bvumman: /* Avoiding Deadlockhttp://www2.chrishardick.com:1099/Notes/Computing/C/pthreads/mutexes.html */

2013-02-21T02:46:59Z

Avoiding Deadlockhttp://www2.chrishardick.com:1099/Notes/Computing/C/pthreads/mutexes.html

← Older revision		Revision as of 02:46, 21 February 2013
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	'''2. Spin lock:'''		'''2. Spin lock:'''

	• The first mutex can be locked without any [http://en.wikipedia.org/wiki/Constraint constraints]. But from here on to lock additional mutexes non-blocking mutexes must be used (pthread_mutex_trylock())		• The first mutex can be locked without any [http://en.wikipedia.org/wiki/Constraint constraints]. But from here on to lock additional mutexes non-blocking mutexes<ref>http://docs.oracle.com/cd/E19683-01/806-6867/sync-36993/index.html</ref> must be used (pthread_mutex_trylock())

	• In case of a failure in any lock, unlock in reverse order and try again.		• In case of a failure in any lock, unlock in reverse order and try again.