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POMulti-threaded random number generator keeps getting a SegFault at initstate_r function
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  1. POMulti-threaded random number generator keeps getting a SegFault at initstate_r function
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    copied!<p>I'm trying to develop a program in C that will generate a given number of random integers. It is supposed to use a given number of threads to speed this up. I found out that the regular random function won't work with threads and am now using random_r instead. I keep getting a SegFault at the initstate_r function, which doesn't make sense because I'm trying to initialize variables, not access them. Can anyone tell me what I'm doing wrong here? (The initstate_r function needs to stay in the generateRandomNumbers function.)</p> <p>Here is the code:</p> <pre><code>#include &lt;errno.h&gt; #include &lt;stdlib.h&gt; #include &lt;unistd.h&gt; #include &lt;stdio.h&gt; // must include stdio for pvm3.h to compile correctly #include &lt;sys/times.h&gt; /* for times system call */ #include &lt;sys/time.h&gt; /* for gettimeofday system call */ #include &lt;pthread.h&gt; /*#define DEBUG 1*/ #define RANDOM_SEED 12345678 //The main work routine //void generateRandomNumbers(long long); void *generateRandomNumbers(void *); double getMilliSeconds(); /* The main work routine */ //void generateRandomNumbers(long long int count) void *generateRandomNumbers(void *arg) { struct random_data buf; int32_t result; char rand_statebuf; printf("hold 1\n"); // This is the function that gives me a SegFault initstate_r(RANDOM_SEED, &amp;rand_statebuf, 128, &amp;buf); printf("hold 2\n"); long long int* count = (long long int*) arg; //printf("Count for thread ID# %ld is %lld\n", pthread_self(), *count); long long int i; //long int x; srandom_r(RANDOM_SEED, &amp;buf); for (i = 0; i &lt; *count; i++) { random_r(&amp;buf, &amp;result); #ifdef DEBUG printf("%ld\n", result); #endif } pthread_exit(NULL); } int main(int argc, char **argv) { long long int count, newCount; int numThreads; //pthread_t *tids; double timeStart = 0; double timeElapsed = 0; if (argc &lt; 3) { fprintf(stderr, "Usage: %s &lt;n&gt;\n" ,argv[0]); exit(1); } sscanf(argv[1],"%lld",&amp;count); /* lld for long long int */ sscanf(argv[2],"%d",&amp;numThreads); pthread_t tids[numThreads]; newCount = count/numThreads; timeStart = getMilliSeconds(); //And we are off int i; for (i=0; i&lt;numThreads; i++) { pthread_create(&amp;tids[i], NULL, generateRandomNumbers, (void *) &amp;newCount); //pthread_join(tids[i], NULL); } int j; for (j=0; j&lt;numThreads; j++) { pthread_join(tids[j], NULL); } //generateRandomNumbers(count); printf("generated %lld random numbers\n", count); timeElapsed = getMilliSeconds() - timeStart; printf("Elapsed time: %lf seconds\n",(double)(timeElapsed/1000.0)); fflush(stdout); exit(0); } </code></pre>
 

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