Today, my server is out of disk and i see there are lot of files in /tmp , their names are phpXXXX , i know these files are uploaded by PHP, but why they are not deleted after the scripts end. After a lot of troubleshooting , i found that there is some errors in my apache error log with “child process exit , filesize limit…” i did some research , and found that it’s because apache can not work with file larger than 2GB , i searched though my file system and saw there are some of my application logs files generated files at 2GB , after deleting them , i’m fine.
In your case, it maybe not your application logs , it could be your apache logs , check /var/log/apache2 or other log files.