Sleep Duration Precision on Windows
On Windows systems, precise sleep durations below one millisecond can be challenging to achieve. The only available sleep function, Sleep, operates with millisecond granularity. This limitation contrasts with Unix systems, which offer multiple options such as sleep, usleep, and nanosleep for more refined sleep control.
One common approach to achieving microsecond sleep on Unix involves the select system call. However, this method proves ineffective on Windows. The reason lies in the nature of sleep functions. The specified parameter represents a minimum sleep duration, not a guaranteed one. The thread may not awaken precisely as requested.
Threads do not inherently "wake up" at a specific time but are rather scheduled for execution by the operating system. The scheduler may choose to exceed the requested sleep duration, particularly if other threads remain active during that interval. Therefore, the notion of precise sleep durations below a millisecond on Windows is often impractical.
The above is the detailed content of Why Is Precise Sub-Millisecond Sleep Difficult to Achieve on Windows?. For more information, please follow other related articles on the PHP Chinese website!