Bug #75488 [NEW]: Under heavy load PHP misses Opcache hits with no errors

From: david at davidfavor dot com Operating system: Ubuntu Zesty PHP version: 7.1.11 Package: opcache Bug Type: Bug Bug description:Under heavy load PHP misses Opcache hits with no errors Description: ------------ 1) Create a simple hello.php (Hello World) file. 2) Run the following... while : ; do curl -s -I -L https://foo.com/hello.php >/dev/null ; done 3) Track FPM access log. First all's well. 100% cache hits + FPM access log shows 0.00% CPU time for script execution. Then odd behavior begins. First huge CPU time number begin, ranging from 1-10+ seconds. Looking at Opcache stats, 99% hits for a few minutes. Then cache hit rate begins to drop also. I've setup opcache logging with log verbosity == 4 + nothing useful comes out. No Apache to FPM communication errors logged. No FPM errors logged (running in at debug level). No FPM slow log entries. I've gone through Opcache config + see no setting which might explain this. I'm using the ondrej:php + ondrej:apache2 PPAs so, Apache-2.4.29-0.1 + PHP-7.1.11-1 are my versions. My... Command Line Kung Fu is strong... so if someone can suggest how to debug this deeper, let me know. Test script: --------------- <html> <head> <title>PHP Test</title> </head> <body> <?php echo '<p>Hello World</p>'; ?> </body> </html> Expected result: ---------------- Expected result 100% cache hits. Actual result: -------------- Roughly 1 out of 30ish requests fail to come from cache. -- Edit bug report at https://bugs.php.net/bug.php?id=75488&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=75488&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=75488&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=75488&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=75488&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=75488&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=75488&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=75488&r=needscript Try newer version: https://bugs.php.net/fix.php?id=75488&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=75488&r=support Expected behavior: https://bugs.php.net/fix.php?id=75488&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=75488&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=75488&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=75488&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=75488&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=75488&r=dst IIS Stability: https://bugs.php.net/fix.php?id=75488&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=75488&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=75488&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=75488&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=75488&r=mysqlcfg