[ESP32] utime.sleep_ms does not free GIL on small intervals #5344
Description
When using multithreading on the ESP32 port, and using sleep_ms(1) to yield to another thread that may be waiting on the GIL, the sleep_ms implementation does not free the GIL when milliseconds is approximately less than 10ms. This is because there is an early break from the sleep loop that doesn't call MICROPY_EVENT_POLL_HOOK
https://github.com/micropython/micropython/blob/master/ports/esp32/mphalport.c#L120-L138
By changing the inner loop from
for (;;) {
uint64_t t1 = esp_timer_get_time();
dt = t1 - t0;
if (dt + portTICK_PERIOD_MS * 1000 >= us) {
// doing a vTaskDelay would take us beyond requested delay time
break;
}
MICROPY_EVENT_POLL_HOOK
ulTaskNotifyTake(pdFALSE, 1);
}
to
for (;;) {
MICROPY_EVENT_POLL_HOOK
uint64_t t1 = esp_timer_get_time();
dt = t1 - t0;
if (dt + portTICK_PERIOD_MS * 1000 >= us) {
// doing a vTaskDelay would take us beyond requested delay time
break;
}
ulTaskNotifyTake(pdFALSE, 1);
}
The GIL will always be freed from this thread, even if the sleep_ms duration is very small, allowing another thread to access python objects and perform work that the main thread may be waiting on.