The sqlite3_sleep() function causes the current thread to suspend execution for at least a number of milliseconds specified in its parameter.
If the operating system does not support sleep requests with millisecond time resolution, then the time will be rounded up to the nearest second. The number of milliseconds of sleep actually requested from the operating system is returned.
SQLite implements this interface by calling the xSleep() method of the default sqlite3_vfs object. If the xSleep() method of the default VFS is not implemented correctly, or not implemented at all, then the behavior of sqlite3_sleep() may deviate from the description in the previous paragraphs.