View thread created by a app compiled by g++ in Windows - multithreading

Question

I created a simple C++ multi-threaded program using g++ under Cygwin in Windows.
#include <unistd.h>
#include <thread> // std::thread
using namespace std;
void thread_func(void)
{
sleep(20);
}
int main()
{
thread th1(thread_func);
thread th2(thread_func);
th1.join();
th2.join();
}
I am guessing the threads are implemented in some Windows library, using Windows native thread. And guessing that is why they don't show in "ps" or "ps -W" when run in cygwin. I only see one entry, when I a expecting three.
Is there some other tool I can use in cygwin or native windows tools to get the complete list of threads?
Thank you,
Ahmed.

Answer 1

ps shows processes not threads.
You can use strace; assuming your program is thread.cpp
g++ -ggdb thread.cpp -o thread
strace -o thread.strace thread.exe
you can see when the threads where initiated at pthread::thread_init_wrapper
$ grep thread thread.strace
--- Process 7404 thread 7840 created
--- Process 7404 thread 8804 created
--- Process 7404 thread 8920 created
--- Process 7404 thread 8004 created
635 4552571 [ldap_init] t 7404 cygthread::stub: thread 'ldap_init', id 0x1F44, stack_ptr 0xC1CCD0
--- Process 7404 thread 4364 created
400 9133089 [t] t 7404 pthread::thread_init_wrapper: tid 0xFFDFCE00
--- Process 7404 thread 5740 created
340 9133541 [t] t 7404 pthread::thread_init_wrapper: tid 0xFFBFCE00
--- Process 7404 thread 4364 exited with status 0x0
--- Process 7404 thread 5740 exited with status 0x0
--- Process 7404 thread 8804 exited with status 0x0
--- Process 7404 thread 7840 exited with status 0x0
--- Process 7404 thread 1328 exited with status 0x0
--- Process 7404 thread 8004 exited with status 0x0
You can also use gdb but it is a bit more complicated.