On Tue, Jun 20, 2023 at 5:32 AM Bảo Phan Quốc <phq...@gmail.com> wrote: > > I'm using cgo to call a C function from Go. Inside the C function there is a > callback to a Go function. In other way, I'm calling Go -> C -> Go. > > After running pprof, I noticed that the __GI___pthread_mutex_unlock took half > of the execution time. AFAIK, cgo has an overhead, especially calling back > from C to Go. But it's weird that cgo takes half of the execution time to do > some locking. Is there something wrong in my code?
Every call from C to Go does acquire a mutex to check that the Go runtime has been fully initialized. This is normally not a big deal as the mutex is held only briefly. But your code does a lot of parallel calls from C to Go. It is possible that the heavy contention on the mutex is causing the results that you are seeing. The code in question is the C function _cgo_wait_runtime_init_done in runtime/gco/gcc_libinit.c. It might be possible to speed it up in some way to avoid the mutex in the normal case. Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcU7Csb_hf5gvy8dVHKEHd8GFkN-fUML18uW0HiQGOAXyg%40mail.gmail.com.
