Designed by Junyi Yang([email protected])

In this lab, we'll see the POSIX.1-2001 threads interfaces, also known as pthreads for POSIX threads. Here I assume that you know the threads, otherwise you need to read our textbook.

We'll briefly introduce pthreads, and you need to see the UNIX system manuals for details. Search engines can also help you.

	#include <pthread.h>

	/* Compare two thread IDs */
	int pthread_equal(pthread_t tid1, pthread_t tid2);

	/* Obtain thread ID */
	pthread_t pthread_self(void);

	#include <pthread.h>

	int pthread_create(pthread_t *thread,
						const pthread_attr_t *attr,
						void *(*start_routine)(void *),
						void *arg);

• This function returns 0 if OK or error number on failure.
• The memory location pointed to by thread is set to the thread ID.
• The attr argument is used to customize various thread attributes.
• The new thread starts running at the address of the start_toutine.
• The arg argument is the parameter of start_toutine.

A single thread can exit in following three ways.

• Return from the start routine. The return value is the thread's exit code.

• The thread can be canceled by another thread in the same process.

   #include <pthread.h>
  
   int pthread_cancel(pthread_t thread);
  

• The thread can call pthread_exit.

   #include <pthread.h>
  
   void pthread_exit(void *retval);
  

  • The retval argument is a typeless pointer which is available to other threads in the process by calling the pthread_join function. We'll talk about pthread_join later.

Example: We have provided a sample program, CreateAndExit.c. Use gcc CreateAndExit.c -pthread -o CreateAndExit to complie it.

#include <pthread.h>

int pthread_join(pthread_t thread, void **retval);

int pthread_attr_init(pthread_attr_t *attr);
int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate);

We can use pthread_join to wait for the thread to terminate. In order to achieve that, you need to use pthread_attr_init and pthread_attr_setdetachstate.

See UNIX system manuals and textbook for details.

Example: We have provided a sample program, Joining.c. Use gcc Joining.c -pthread -o Joining to compile it.

#include <pthread.h>

int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *mutexattr);

int pthread_mutex_lock(pthread_mutex_t *mutex);

int pthread_mutex_trylock(pthread_mutex_t *mutex);

int pthread_mutex_unlock(pthread_mutex_t *mutex);

int pthread_mutex_destroy(pthread_mutex_t *mutex);

See UNIX system manuals and textbook for details.

#include <pthread.h>

pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

int pthread_cond_init(pthread_cond_t *cond, pthread_condattr_t *cond_attr);

int pthread_cond_signal(pthread_cond_t *cond);

int pthread_cond_broadcast(pthread_cond_t *cond);

int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex);

int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, const struct timespec *abstime);

int pthread_cond_destroy(pthread_cond_t *cond);

See UNIX system manuals and textbook for details.

• See CreateAndExit.c and run it.
• See Joining.c and run it.
• Read the textbook, Chapter 26-31.
• Write a program that creates three threads and read an integer a which is between 1 and 9 as input. Let thread one calculate $a!$. Let thread two calculate $a^a$. And let thread three calculate the sum of the two, which means $a!+a^a$. Yon need to let thread three use the results of thread one and two.

• UNIX system manuals
• W. Richard Stevens, Stephen A. Rago. Advanced Programming in the Unix Environment, Third Edition. Person Education, Inc.. 2013
• Operating System: Three Easy Pieces