Emscripten uses a worker pool. I will create a new worker each time a pthread is created and there are no free workers in the pool.
Assuming DoWork doesn't take too long then in your case the workers should be returned to the pool as re-used. The total number of workers at any time will be the maximum number of simultaneous DoWork requests that you have had. Because workers are fairly expensive to create we never currently shrink the pool. In theory such an option could be added.. cheers, sam On Wed, Nov 12, 2025 at 8:10 PM themixup <[email protected]> wrote: > Hello, > > I am writing to ask about an issue I'm facing where pthreads do not seem > to be released properly. > > In my React application, I need to perform a specific task every time the > user provides keyboard input. My approach was to spawn a new thread for > each key-press and then detach it. > > However, after continuous typing, the application crashes. > > When I checked the Chrome debugger, I could see dozens of "em-thread"s > (Emscripten worker threads) accumulating. It appears that the threads I > create are not terminating or being cleaned up, even after their work is > complete. > > The pattern I was using is as follows: > // This is called on every keyboard input > void CreateWorkerThread() { > pthread_t thread; > pthread_create(&thread, NULL, DoWork, NULL); > pthread_detach(thread); > } > > void* DoWork(void* arg) { > // Perform a specific task... > // I am certain this function finishes its execution. > return NULL; > } > > I have already implemented a workaround by changing my design to call > pthread_create only once (using a persistent worker thread and a message > queue), which has resolved the memory issue and the crash. > > However, I am still curious why the original approach failed. Is it > expected behavior that frequently creating and detaching threads in > Emscripten will cause them to accumulate without being released? Is there a > proper way to handle this "fire-and-forget" threading pattern? > > Thank you for any insights. > > ------------------------------ > 본 이메일은 *기밀 정보를 포함*하고 있으며, 지정된 수신인에게만 전달되었습니다. 만약 귀하가 의도된 수신인이 아니라면, 이 > 이메일의 내용을 열람, 사용 또는 배포하는 것을 *엄격히 금지*합니다. 만일 이 이메일을 잘못 수신하셨다면, 즉시 삭제해 주시고 > 발신자에게 알려주시기 바랍니다.(This email contains *confidential information* and is > intended solely for the designated recipient(s). If you are not the > intended recipient, you are hereby notified that any disclosure, copying, > distribution, or use of the contents of this email is *strictly > prohibited*. If you have received this email in error, please delete it > immediately and notify the sender.) > > -- > You received this message because you are subscribed to the Google Groups > "emscripten-discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/emscripten-discuss/7a2ad872-664e-46a1-88b2-b359886d2f30n%40googlegroups.com > <https://groups.google.com/d/msgid/emscripten-discuss/7a2ad872-664e-46a1-88b2-b359886d2f30n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/emscripten-discuss/CAL_va2_X-wJKo45%3Dj_Pp8QM%2BV%2BdgampyeSznzLxpLQj%2BF7Rupg%40mail.gmail.com.
