1. Advanced UNIX programming
Fall 2002
Instructor: Ashok Srinivasan
Lecture 32
Acknowledgements: The syllabus and power point presentations are modified versions of those by T. Baker and X. Yuan

2. Announcements Reading assignment Project Assignment 3 Chapter 23
One page accomplishments report
Due Friday, 15 Nov 2002
Assignment 3
Test client and parameters available

3. Week 12 Topics Threads Basic thread functions
Some more thread functions
Thread-specific data
Mutual exclusion
Conditional variables

4. Thread-specific data Thread specific global data
Regular global data is shared by all threads
We need to use them very carefully to avoid creating bugs
See example1.c, example2.c, and example3.c
Pthreads has a means to create thread specific global data
“Global variables” that are not shared by other threads
It is a common technique for making an existing function thread safe
See example4.c
Corrects errors in example2.c and example3.c

5. Thread-specific data (continued)
int pthread_once(pthread_once_t *oneptr, void (*init)(void));
int pthread_key_create(pthread_key_t *keyptr, void (*destructor) (void *pointer));
void *pthread_getspecific(pthread_key_t key);
int pthread_setspecific(pthread_key_t key, const void *value);
See example4.c for the use of these functions