> It appears to be better to use clock_gettime(CLOCK_MONOTONIC) > where available and only use gettimeofday() as fallback solution > together with times(), ftime() and time(). Ok, I've tried and it's less good than expected. Using CLOCK_MONOTONIC absolutely kills efficiency. CLOCK_REALTIME is ok but it has no obvious benefits (microsecond resolution as given by gettimeofday() is probably sufficient). The explanation AFAICT is that pthread_cond_timedwait() waits for absolute clock values as given by CLOCK_REALTIME. CLOCK_MONOTONIC gives other values (the man page says: "represents monotonic time since some unspecified starting point"). These values are probably "in the past" as seen from pthread_cond_timedwait(), which implies a busy loop of waiting for the GIL to be released, inside of being suspended gracefully until the timeout. I can still produce a patch with only CLOCK_REALTIME but I'm not sure it's worth the code complication.