PHP Memory Leak Issue

Oct 12, 2013, by admin

When processing a large number of records or calling objects with recursive references, a memory leak can occur causing PHP to run out of memory. PHP 5.3 has a garbage collector gc_enable() that can collect cyclic references. You can also avoid the memory leak issue by manually calling the destructors and unsetting the recursive ref like below.

1. <?php
2. class A {
3. function __construct () {
4. $this->b = new B($this);
5. }
6. function __destruct () {
7. $this->b->__destruct();
8. }
9. }
11. class B {
12. function __construct ($parent = NULL) {
13. $this->parent = $parent;
14. }
15. function __destruct () {
16. unset($this->parent);
17. }
18. }
20. for ($i = 0 ; $i < 5000000 ; $i++) {
21. $a = new A();
22. $a->__destruct();
23. }
25. echo number_format(memory_get_usage());
26. ?>

Also Memory leak issue can occur due to server configuration, so make sure to check it at server end.