[tsan] Remove long sleeps from fork tests

[kubamracek]

Summary

On one of our testing machines, we're running the tests under heavy load, and especially in the fork-based TSan tests, we're seeing timeouts when a test uses sleep(10), assuming that calling fork() on another thread will finish sooner than that.

This patch removes the timeouts. I'm not sure if there is a better way, especially since these timeouts are supposed to catch deadlocks, and removing them might not be a good idea. Dmitry, if you have a better solution, please suggest.

[dvyukov]

Why do tests timeout if there is a sleeping thread present? Do they deadlock?
If anything, I would expect that a spinning thread will make situation worse on an overloaded machine.

[kubamracek]

Fork takes a long time on OS X (due to the large mmap TSan regions), much longer than on Linux. On that system, it even takes longer than 10 seconds. Spinning is bad, but it will at least make the test pass.

[dvyukov]

OK, I see.

For the sleeper thread please either increase sleep duration (1e6 seconds is OK here), or call sleep(1) in a loop. sched_yield will consume whole core.

For the watchdog thread, I've tried to be nicer to LLVM buildbots. But I don't remember that it ever fired. So I guess it is OK to remove it.

[kubamracek]

Updating patch.

compiler-rt/trunk/test/tsan/fork_deadlock.cc

 // RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=atexit_sleep_ms=50 %run %t 2>&1 | FileCheck %s
 #include "test.h"
 #include <errno.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 
 int counter;
 
 static void *incrementer(void *p) {
   for (;;)
     __sync_fetch_and_add(&counter, 1);
   return 0;
 }
 
-static void *watchdog(void *p) {
-  sleep(100);  // is not intended to exit
-  fprintf(stderr, "timed out after 100 seconds\n");
-  exit(1);
-  return 0;
-}
-
 int main() {
   barrier_init(&barrier, 2);
-  pthread_t th1, th2;
+  pthread_t th1;
   pthread_create(&th1, 0, incrementer, 0);
-  pthread_create(&th2, 0, watchdog, 0);
   for (int i = 0; i < 10; i++) {
     switch (fork()) {
     default:  // parent
       while (wait(0) < 0) {}
       fprintf(stderr, ".");
       break;
     case 0:  // child
       __sync_fetch_and_add(&counter, 1);

compiler-rt/trunk/test/tsan/fork_multithreaded.cc

 // RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s -check-prefix=CHECK-DIE
 // RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=die_after_fork=0 %run %t 2>&1 | FileCheck %s -check-prefix=CHECK-NODIE
 #include "test.h"
 #include <errno.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 
 static void *sleeper(void *p) {
-  sleep(10);  // not intended to exit during test
+  sleep(1000);  // not intended to exit during test
   return 0;
 }
 
 static void *nop(void *p) {
   return 0;
 }
 
 int main() {