stuff

Examples/concurrency/race.c

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+/*
+ * race.c - Shows the race condition that can happen
+ *          then threads try to modify multiple global
+ *          values at the same time
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <pthread.h>
+
+// start flag
+volatile int start = 0;
+
+// shared global
+static int counter1 = 0;
+static int counter2 = 0;
+
+void* thread_routine(void* args)
+{
+	int me = *((int *)args);
+	int you = me ? 0 : 1;
+
+	printf("Worker thread: %d ready, you are %d\n", me, you);
+
+	// wait for start from master thread
+	while(!start);
+
+	for (int j = 0; j < 100000000; j++)
+	{
+		// this is the critical section
+		counter1++;
+		counter2++;
+		// leaving critical section
+	}
+
+	printf("Worker thread: %d done\n",me);
+
+	return NULL;
+}
+
+int main()
+{
+	int val1 = 0;
+	int val2 = 1;
+	
+	pthread_t thr1;
+	pthread_t thr2;
+	if(pthread_create(&thr1, NULL, thread_routine, (void*)&val1) == -1) {
+		printf("COULD NOT CREATE A THREAD\n");
+		exit(EXIT_FAILURE);
+	}
+	if(pthread_create(&thr2, NULL, thread_routine, (void*)&val2) == -1) {
+		printf("COULD NOT CREATE A THREAD\n");
+		exit(EXIT_FAILURE);
+	}
+
+	start = 1;
+
+	pthread_join(thr1,NULL);
+	pthread_join(thr2,NULL);
+
+	printf("counter1: %d\n",counter1);
+	printf("counter2: %d\n",counter2);
+	return EXIT_SUCCESS;
+}
+