53 lines
1.3 KiB
C
53 lines
1.3 KiB
C
/*
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* pthreads2.c - Shows how to create and wait for multple
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* threads (beyond the main thread)
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* Threads prints out its thread ID and process ID.
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* Shows that threads share the same process ID
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* but all have their own thread ID
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*/
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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int global_value = 10;
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// thread_routine
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// writes to a global variable - shows that
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// global data is shared between threads
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//
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// NOTE: that parameters and return value are pointers
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void* thread_routine()
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{
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for(int i = 0; i < 10; i++) {
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printf("%lu %d: THREAD READS GLOBAL VALUE: %d\n", pthread_self(), getpid(), global_value);
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global_value++;
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sleep(1);
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}
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return NULL;
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}
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int main()
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{
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// Create 5 threads
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pthread_t thr_id[5];
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for(int i = 0; i < 5; i++) {
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if(pthread_create(&thr_id[i], NULL, thread_routine, NULL) == -1) {
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printf("COULD NOT CREATE A THREAD\n");
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exit(EXIT_FAILURE);
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}
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}
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// Wait for all threads to finish
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for(int i = 0; i < 5; i++) {
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pthread_join(thr_id[i], NULL);
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}
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// Print out final value of global data
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printf("%lu %d PARENT READS GLOBAL: %d\n", pthread_self(), getpid(), global_value);
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// Return success
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return 0;
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}
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