while tried to access /config/issue page, the webpage 502.
and the php-fpm log said :
```
[23-Jun-2016 11:23:20] WARNING: [pool www] child 13843 exited with code 1 after 11.368036 seconds from start
[23-Jun-2016 11:23:20] NOTICE: [pool www] child 14062 started
[23-Jun-2016 11:23:20] WARNING: [pool www] child 13872 exited with code 1 after 10.402121 seconds from start
[23-Jun-2016 11:23:20] NOTICE: [pool www] child 14073 started
```
we try to using php built-in to debug
```
strace -v -t -f php -S 0.0.0.0:8003 -t webroot/ webroot/index.php
```
Their seems some zend_mm_heap corrupted
```
11:25:59 stat("/opt/phabricator/src/applications/cache/spec/PhabricatorDataCacheSpec.php", {st_dev=makedev(8, 3), st_ino=393614, st_mode=S_IFREG|0644, st_nlink=1, st_uid=0, st_gid=0, st_blksize=4096, st_blocks=8, st_size=3597, st_atime=2016/06/23-11:06:39, st_mtime=2015/10/29-08:55:25, st_ctime=2015/10/29-08:55:25}) = 0
11:25:59 write(2, "zend_mm_heap corrupted\n", 23zend_mm_heap corrupted
) = 23
```
Our phabricator run on a 2GB memory / 1vCPU core vps.
With PHP version
```
PHP 7.0.7 (cli) (built: May 25 2016 17:35:28) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies
```