We had disabled the build-in crawler during earlier debugging.
Here's a little part of the logfile.log:
root@booba:~# watch -n 60 'ps aux | grep -E "CPU|Memory|php" | awk "{print \$1, \$2, \$3, \$4, \$11}" >> logfile.log'
root@booba:~# cat logfile.log
USER PID %CPU %MEM COMMAND
www-data 3254...