I got an VPS at burst.net, very cheap one, but this doesn't matter.
The strange behavior of it is, the php-cgi process, which started using lighthttpd's spawn-cgi, dies every a few minutes. however, other processes are fine and great, even include a java process, and I'm sure there is no "out of memory" issue, so it's not killed by OOM killer.
I used strace to trace the process, and found out it was killed by SIGKILL, hence no single log was left on the disk, just dies suddenly.
Is there anyway I can find out what process/thing sent the SIGKILL to the poor php process?
Filed a ticket with the vendor, but they said they won't care.
strace -p 7176 Process 7176 attached - interrupt to quit wait4(-1, <unfinished ...> +++ killed by SIGKILL +++