Basic Thread Functions - Advanced Unix Programming - Lecture Slides, Slides of Computer Programming

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Week 11 Topics

• Threads
  • Basic thread functions
  • Some more thread functions
  • Thread-specific data
  • Mutual exclusion
  • Conditional variables

Basic thread functions

• Thread creation int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void (start_routine)(void *), void * arg) - Thread attributes (stack size, scheduling policy) can be modified - Use NULL for default - Returns 0 if successful, and an error number if it fails - EAGAIN: System lacks resources - EINVAL: Invalid attribute - EPERM: Caller does not have appropriate permission - Pthread functions return error values - They do not set errno - New thread executes the function given by start_routine - arg is the argument to this function - The thread ID is stored in *thread

Some more thread functions

• pthread_t pthread_self(void)
  • Get ID of the current thread
• void pthread_exit(void *value_ptr)
  • Exits a thread
• int pthread_detach(pthread_t tid)
  • Make a thread detachable
    • pthread_join will not be called on this thread

Client-server

• Implementing a concurrent server using

pthreads

• example3.c and old.client. c
• What happens if you uncomment the sleep

statements in example3.c?

• example3a.c corrects this problem