Bug #74250 [NEW]: OPcache compilation performance regression in PHP 5.6/7 with huge classes

From: dzuelke at gmail dot com Operating system: Linux PHP version: 7.0.16 Package: opcache Bug Type: Bug Bug description:OPcache compilation performance regression in PHP 5.6/7 with huge classes Description: ------------ There appears to be a performance regression in the CFG and DFA based optimization passes of OPcache in PHP 5.6+ when loading huge classes (such as those generated by Symfony's routing component) for the first time. The issue does not occur on PHP 5.5. Tests below are with 5.6.30, 7.0.16 and 7.1.2 and default INI settings; I replicated the issue on both macOS and Linux. Test file here (it's from an actual application, slightly anonymized, not a synthetic example): https://gist.github.com/dzuelke/fe867f55f09e0bf79ecefcc815b7fe92 Without OPcache, everything is fine in all versions: $ time -p php -dopcache.enable_cli=0 hugeclass.php real 0.10 user 0.09 sys 0.00 With OPcache on, things are suddenly much, much slower: 5.6: $ time -p php -dopcache.enable_cli=1 hugeclass.php real 3.23 user 3.21 sys 0.02 7.0: $ time -p php -dopcache.enable_cli=1 hugeclass.php real 1.76 user 1.73 sys 0.02 7.1: $ time -p php -dopcache.enable_cli=1 hugeclass.php real 4.01 user 3.98 sys 0.02 For comparison, 5.5 is as speedy as you'd expect it to be: $ time -p php -dopcache.enable_cli=1 hugeclass.php real 0.14 user 0.11 sys 0.02 If we switch off optimization passes 5 (CFG based) and 6 (DFA based, only in 7.1), everything is great again in all versions: $ time -p php -dopcache.enable_cli=1 -dopcache.optimization_level=0x7FFFFFCF hugeclass.php real 0.13 user 0.10 sys 0.02 For 5.6 and 7.0, pass 6 is not a thing, but in 7.1, we can inspect passes 5 and 6 separately. Pass 5 (CFG based) already makes for a drastic performance hit in 7.1: $ time -p php -dopcache.enable_cli=1 -dopcache.optimization_level=0x7FFFFFDF hugeclass.php real 0.88 user 0.86 sys 0.01 But pass 6 (DFA based) is the one that causes the biggest slowdown in 7.1: $ time -p php -dopcache.enable_cli=1 -dopcache.optimization_level=0x7FFFFFEF hugeclass.php real 3.29 user 3.24 sys 0.04 In all versions, subsequent loads from the cache (such as when running FPM or the built-in web server) are fast. Confirmed as bug in both CFG and DFA passes by Nikita: http://news.php.net/php.internals/98518 Test script: --------------- https://gist.github.com/dzuelke/fe867f55f09e0bf79ecefcc815b7fe92 -- Edit bug report at https://bugs.php.net/bug.php?id=74250&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=74250&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=74250&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=74250&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=74250&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=74250&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=74250&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=74250&r=needscript Try newer version: https://bugs.php.net/fix.php?id=74250&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=74250&r=support Expected behavior: https://bugs.php.net/fix.php?id=74250&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=74250&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=74250&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=74250&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=74250&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=74250&r=dst IIS Stability: https://bugs.php.net/fix.php?id=74250&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=74250&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=74250&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=74250&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=74250&r=mysqlcfg