89 lines
2.5 KiB
C
89 lines
2.5 KiB
C
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/*
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Written By: Prawar Poudel
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13 Feb 2018
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This is written to demonstrate simple creation and waiting for pthread to terminate
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*/
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#include <pthread.h>
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#include <stdio.h>
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#include <unistd.h>
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#define NUM_THREADS 100
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int mutexProtectedGlobalVariable;
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int unprotectedProtectedGlobalVariable;
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pthread_mutex_t myMutex;
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//this function will update the value without any protection
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void *unprotectedThreadFunc(void* argument)
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{
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int i;
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for( i=0;i<10000;i++) unprotectedProtectedGlobalVariable++; }
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//this function will update the value without any protection
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void *protectedThreadFunc(void* argument)
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{
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int i;
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pthread_mutex_lock (&myMutex);
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for( i=0;i<10000;i++) mutexProtectedGlobalVariable++; pthread_mutex_unlock (&myMutex);
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}
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int main()
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{
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mutexProtectedGlobalVariable = 0;
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unprotectedProtectedGlobalVariable = 0;
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int i;
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//you can create these dynamically also
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pthread_t myThreads[NUM_THREADS];
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int status = 0;
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printf("Calling unprotected set of threads\n");
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//first set of five threads will call a function that will update the variable unprotected
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for(i=0;i<NUM_THREADS;i++)
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{
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status = pthread_create(&myThreads[i],NULL,unprotectedThreadFunc, (void*)i);
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if(status)
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{
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printf("Error in creating the threads: %d\n",i);
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return -1;
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}
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}
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//this is the area that threads will run
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//we will wait for the threads here
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for(i=0;i<NUM_THREADS;i++)
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{
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int retStatus = pthread_join(myThreads[i],NULL);
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if(retStatus)
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{
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printf("Well..... some problem at thread id %d, error no: %d\n",i,retStatus);
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}
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}
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printf("Unprotected sum is %d\n", unprotectedProtectedGlobalVariable); printf("\t\t...end of unprotected set of threads\n");
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printf("Calling protected set of threads\n");
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pthread_mutex_init(&myMutex, NULL);
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//next set of five threads will call a function that will update the variable protected
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for(i=0;i<NUM_THREADS;i++)
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{
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status = pthread_create(&myThreads[i],NULL,protectedThreadFunc, (void*)i);
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if(status)
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{
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printf("Error in creating the threads: %d\n",i);
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return -1;
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}
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}
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//this is the area that threads will run
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//we will wait for the threads here
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for(i=0;i<NUM_THREADS;i++)
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{
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int retStatus = pthread_join(myThreads[i],NULL);
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if(retStatus)
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{
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printf("Well..... some problem at thread id %d, error no: %d\n",i,retStatus);
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}
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}
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pthread_mutex_destroy(&myMutex);
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printf("Protected sum is %d \n", mutexProtectedGlobalVariable); printf("\t\t...end of unprotected set of threads\n");
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return 0;
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}
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