ID: 42659 Updated by: [EMAIL PROTECTED] Reported By: jdolecek at NetBSD dot org -Status: Open +Status: Feedback Bug Type: Date/time related Operating System: win32 only PHP Version: 5.2.4 New Comment:
Please try using this CVS snapshot: http://snaps.php.net/php5.3-latest.tar.gz For Windows (zip): http://snaps.php.net/win32/php5.3-win32-latest.zip For Windows (installer): http://snaps.php.net/win32/php5.3-win32-installer-latest.msi Previous Comments: ------------------------------------------------------------------------ [2007-09-13 15:30:05] jdolecek at NetBSD dot org Description: ------------ When PHP script runs for long time, the value returned by microtime() gradually drifts away from time(). The exact value depends on system, but we've seen 5 hour difference to current time for script running about a week, with drift about 1 minute per 5 minutes run (system running under VMware). The script is daemon-like process, i.e. it's blocked in select() most of time, and only occassionally wakes up to process request. Looking at win32/time.c, I spot one problematic spot in that the code might not notice counter wrap-off if timer happens to be a higher value after wrap-around then the last time the function was called. However, that shouldn't be normally problem, since the counter wraps-around very infrequently. Reproduce code: --------------- <?php ini_set('date.timezone', 'CET'); putenv("TZ=CET"); while(true) { $sec = microtime(true); echo "msec: ". sprintf("[%s.%04d]", date("Y-m-d H:i:s", floor($sec)), (float) ($sec - floor($sec)) * 10000)."\n"; echo "sec : ".date('[Y-m-d H:i:s]')."\n"; sleep(300); } C program which demostrates how the two times diverge (cut&paste from win32/time.c, so please forgive whitespace/style): #include <windows.h> #include <winbase.h> #include <time.h> #include <winsock2.h> int getfilesystemtime(struct timeval *time_Info) { FILETIME ft; __int64 ff; LARGE_INTEGER li; GetSystemTimeAsFileTime(&ft); /* 100 ns blocks since 01-Jan-1641 */ /* resolution seems to be 0.01 sec */ li.u.LowPart = ft.dwLowDateTime; li.u.HighPart = ft.dwHighDateTime; ff = li.QuadPart; time_Info->tv_sec = (int)(ff/(__int64)10000000-(__int64)11644473600ULL); time_Info->tv_usec = (int)(ff % 10000000)/10; return 0; } #define PW32G(x) (x) int main() { LARGE_INTEGER li; __int64 freq, timer; double dt; struct timeval tv, *time_Info = &tv, starttime, tv2; QueryPerformanceFrequency(&li); freq = li.QuadPart; getfilesystemtime(&starttime); QueryPerformanceCounter(&li); timer = li.QuadPart; dt = (double)timer/PW32G(freq); PW32G(starttime).tv_usec -= (int)((dt-(int)dt)*1000000); if (PW32G(starttime).tv_usec < 0) { PW32G(starttime).tv_usec += 1000000; --PW32G(starttime).tv_sec; } PW32G(starttime).tv_sec -= (int)dt; while(1) { sleep(10); QueryPerformanceCounter(&li); getfilesystemtime(&tv2); timer = li.QuadPart; dt = (double)timer/PW32G(freq); time_Info->tv_sec = PW32G(starttime).tv_sec + (int)dt; time_Info->tv_usec = PW32G(starttime).tv_usec + (int)((dt-(int)dt)*1000000); if (time_Info->tv_usec > 1000000) { time_Info->tv_usec -= 1000000; ++time_Info->tv_sec; } printf("%ld.%06ld\n", tv2.tv_sec - time_Info->tv_sec, tv2.tv_usec - time_Info->tv_usec); } } Expected result: ---------------- the time on 'msec' line should be same as for 'sec' line. Since the second date() call fetches time after the microtime() call, the 'sec' line may print time 1 second after the 'msec' line occassionally, but the times should match most of the time. The C program should print ~constant time difference. Actual result: -------------- The longer the script runs, the bigger difference between the 'msec' and 'sec' time. Example output (after about 12 hours): msec: [2007-09-13 12:22:25.7074] sec : [2007-09-13 12:22:26] msec: [2007-09-13 12:27:25.6848] sec : [2007-09-13 12:27:26] msec: [2007-09-13 12:32:25.6624] sec : [2007-09-13 12:32:26] It _appears_ microtime() loses about 0.02 seconds on each 5 minute measurement on this machine, but this may be just local value and the exact value could differ on different hardware. C program output (from start): 0.002466 0.002998 0.003723 It appears performance counter based time loses about 0.0006 sec on each 10 second measurement compared to GetSystemTimeAsFileTime(). This matches the difference observed in PHP script. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=42659&edit=1
