How to make Google Test detect the number of threads on Linux?

Question

When running the death tests written using Google Test framework the following warning is produced for each of the tests:

[WARNING] .../gtest-death-test.cc:789:: Death tests use fork(), which is unsafe
particularly in a threaded context. For this test, Google Test couldn't detect
the number of threads.

Is there a way to make Google Test detect the number of threads on Linux?

Answer 1

I've looked at the source code and it turned out that detection of the number of threads is implemented only for MacOS X and QNX, but not on Linux or other platforms. So I implemented missing functionality myself by counting the number of entries in /proc/self/task. Since it might be useful for others I'm posting it here (I've also sent it to the Google Test group):

size_t GetThreadCount() {
  size_t thread_count = 0;
  if (DIR *dir = opendir("/proc/self/task")) {
    while (dirent *entry = readdir(dir)) {
      if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0)
        ++thread_count;
    }
    closedir(dir);
  }
  return thread_count;
}

As of 25 August 2015, Google Test implements GetThreadCount on Linux:

size_t GetThreadCount() {
  const string filename =
      (Message() << "/proc/" << getpid() << "/stat").GetString();
  return ReadProcFileField<int>(filename, 19);
}