Bug #74792 [NEW]: Cycles created by AppendIterator not cleaned.

From: arjen at parse dot nl Operating system: All PHP version: 7.1.6 Package: SPL related Bug Type: Bug Bug description:Cycles created by AppendIterator not cleaned. Description: ------------ Cycles where an AppendIterator is involved are not collected, I guess the algorithm cannot look inside the internal iterators. When only using an ArrayIterator, GC works as expected. See https://3v4l.org/BCI0F#v700 Test script: --------------- <?php class A { protected $_iterator; protected $_appendIterator; public function __construct($appendIterator = true) { $this->_appendIterator = $appendIterator; $arrayIterator= new ArrayIterator([$this, $this, $this, $this]); if ($appendIterator) { $this->_iterator = new AppendIterator(); $this->_iterator->append($arrayIterator); } else { $this->_iterator = $arrayIterator; } } public function __destruct() { echo 'destructing A::class(' . var_export($this->_appendIterator, true) .') ' . PHP_EOL; } } echo "Running with AppendIterator(): " . PHP_EOL; $mStart = memory_get_usage(); for ($i = 0; $i < 10; $i++) new A(); echo memory_get_usage() - $mStart . " memory increase " . PHP_EOL; echo "Running GC.." . PHP_EOL; echo "Found " . gc_collect_cycles() . " cycles..." . PHP_EOL . PHP_EOL; echo "Running without AppendIterator(): " . PHP_EOL; $mStart = memory_get_usage(); for ($i = 0; $i < 10; $i++) new A(false); echo memory_get_usage() - $mStart . " memory increase " . PHP_EOL; echo "Running GC.." . PHP_EOL; echo "Found " . gc_collect_cycles() . " cycles..." . PHP_EOL; echo "Done!" . PHP_EOL . PHP_EOL; Expected result: ---------------- Cycles also collected when AppendIterator is between A->iterator and ArrayIterator. Actual result: -------------- No cycles found -- Edit bug report at https://bugs.php.net/bug.php?id=74792&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=74792&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=74792&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=74792&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=74792&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=74792&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=74792&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=74792&r=needscript Try newer version: https://bugs.php.net/fix.php?id=74792&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=74792&r=support Expected behavior: https://bugs.php.net/fix.php?id=74792&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=74792&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=74792&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=74792&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=74792&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=74792&r=dst IIS Stability: https://bugs.php.net/fix.php?id=74792&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=74792&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=74792&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=74792&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=74792&r=mysqlcfg