Count threads after thread-creation while still holding mutex lock
The `Mutex` is locked with the `MutexLock` before spawning the thread, so that the thread is prevented from completing (by being blocked on `Mutex`) before the new thread count is obtained. However, the existing bug (introduced in 22e6055) releases `Mutex` before obtaining the new thread count, which allows the thread to run to completion in the meantime.
Also, since the `(thread_count_after_create != starting_count + 1)` condition (line 328) skips the remainder of the `for`-loop body on every iteration, `thread_count_after_join` stays uninitialized.
I believe this is why [this test failed][1] on the macOS CI with this trace:
```
[----------] 1 test from GetThreadCountTest
[ RUN ] GetThreadCountTest.ReturnsCorrectValue
googletest/test/googletest-port-test.cc:350: Failure
Expected equality of these values:
thread_count_after_create
Which is: 1
starting_count + 1
Which is: 2
googletest/test/googletest-port-test.cc:351: Failure
Expected equality of these values:
thread_count_after_join
Which is: 140493185949400
starting_count
Which is: 1
[ FAILED ] GetThreadCountTest.ReturnsCorrectValue (2 ms)
[----------] 1 test from GetThreadCountTest (2 ms total)
```
[1]: https://github.com/google/googletest/actions/runs/6064919420/job/16453860690?pr=3049
diff --git a/googletest/test/googletest-port-test.cc b/googletest/test/googletest-port-test.cc
index e0793ba..8d21026 100644
--- a/googletest/test/googletest-port-test.cc
+++ b/googletest/test/googletest-port-test.cc
@@ -296,7 +296,7 @@
TEST(GetThreadCountTest, ReturnsCorrectValue) {
size_t starting_count;
size_t thread_count_after_create;
- size_t thread_count_after_join;
+ size_t thread_count_after_join = 0;
// We can't guarantee that no other thread was created or destroyed between
// any two calls to GetThreadCount(). We make multiple attempts, hoping that
@@ -316,9 +316,9 @@
const int status = pthread_create(&thread_id, &attr, &ThreadFunc, &mutex);
ASSERT_EQ(0, pthread_attr_destroy(&attr));
ASSERT_EQ(0, status);
- }
- thread_count_after_create = GetThreadCount();
+ thread_count_after_create = GetThreadCount();
+ }
void* dummy;
ASSERT_EQ(0, pthread_join(thread_id, &dummy));
