Bug #80447 [NEW]: Strange out of memory error when running with JIT

From: dac514 at hotmail dot com Operating system: Ubuntu PHP version: 8.0.0 Package: Unknown/Other Function Bug Type: Bug Bug description:Strange out of memory error when running with JIT Description: ------------ In the last few days benchmarksgame-team.pages.debian.net upgraded to PHP8. This script; https://benchmarksgame-team.pages.debian.net/benchmarksgame/program/binarytrees-php-4.html When run with JIT: `/opt/src/php-8.0.0/bin/php -dzend_extension=/opt/src/php-8.0.0/lib/php/extensions/no-debug-non-zts-20200930/opcache.so -dopcache.enable_cli=1 -dopcache.jit_buffer_size=64M -n -d memory_limit=4096M binarytrees.php-4.php 21` Runs out of memory, very unusually, (it did not run out of memory in previous versions of PHP) The following weird hack is a workaround, change: ``` function createTree($depth) { if (!$depth) { return [null, null]; ``` To: ``` function createTree($depth) { echo ''; if (!$depth) { return [null, null]; ``` I don't get it? Test script: --------------- function createTree($depth) { // echo ''; // TODO: This hack works?! if (!$depth) { return [null, null]; } $depth--; return [ createTree($depth), createTree($depth) ]; } function checkTree($treeNode) { return 1 + ($treeNode[0][0] === null ? 1 : checkTree($treeNode[0])) + ($treeNode[1][0] === null ? 1 : checkTree($treeNode[1])); } $minDepth = 4; $n = ($argc == 2) ? $argv[1] : 1; $maxDepth = max($minDepth + 2, $n); $stretchDepth = $maxDepth + 1; $stretchTree = createTree($stretchDepth); echo "stretch tree of depth $stretchDepth\t check: ", checkTree($stretchTree), PHP_EOL; unset($stretchTree); $longLivedTree = createTree($maxDepth); function startWorker($depth, $iter, $n, $size, $shmId) { $pid = pcntl_fork(); if ($pid) { return $pid; } else { $check = 0; for ($i = 1; $i <= $iter; ++$i) { $t = createTree($depth); $check += checkTree($t); unset($t); } $result = "$iter\t trees of depth $depth\t check: $check\n"; shmop_write($shmId, $result, $size * ($n - 1)); exit(0); } } $iterations = 1 << ($maxDepth); $depthIterations = [$minDepth => $iterations]; do { $minDepth += 2; if ($minDepth <= $maxDepth) { $iterations >>= 2; $depthIterations[$minDepth] = $iterations; } } while ($minDepth <= $maxDepth); extension_loaded('shmop') or dl('shmop.so'); $size = 128; $shmId = shmop_open(ftok(__FILE__, 'b'), 'c', 0644, $size * (count($depthIterations) + 1)); $PIDs = []; $n = 0; foreach ($depthIterations as $d => $i) { $PIDs[] = startWorker($d, $i, ++$n, $size, $shmId); } foreach ($PIDs as $PID) { pcntl_waitpid($PID, $status); } foreach (range(1, count($depthIterations)) as $n) { echo trim(shmop_read($shmId, $size * ($n - 1), $size)), PHP_EOL; } shmop_delete($shmId); echo "long lived tree of depth $maxDepth\t check: ", checkTree($longLivedTree), PHP_EOL; Expected result: ---------------- PROGRAM OUTPUT: stretch tree of depth 22 check: 8388607 2097152 trees of depth 4 check: 65011712 524288 trees of depth 6 check: 66584576 131072 trees of depth 8 check: 66977792 32768 trees of depth 10 check: 67076096 8192 trees of depth 12 check: 67100672 2048 trees of depth 14 check: 67106816 512 trees of depth 16 check: 67108352 128 trees of depth 18 check: 67108736 32 trees of depth 20 check: 67108832 long lived tree of depth 21 check: 4194303 Actual result: -------------- Out of memory error. Terminated. -- Edit bug report at https://bugs.php.net/bug.php?id=80447&edit=1 -- Fix committed: https://bugs.php.net/fix.php?id=80447&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=80447&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=80447&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=80447&r=needscript Try newer version: https://bugs.php.net/fix.php?id=80447&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=80447&r=support Expected behavior: https://bugs.php.net/fix.php?id=80447&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=80447&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=80447&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=80447&r=globals PHP version support discontinued: https://bugs.php.net/fix.php?id=80447&r=phptooold Daylight Savings: https://bugs.php.net/fix.php?id=80447&r=dst IIS Stability: https://bugs.php.net/fix.php?id=80447&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=80447&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=80447&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=80447&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=80447&r=mysqlcfg