Category: sysadmin

  • High System CPU usage

    After upgrading a webserver running Apache to Debian Jessie (from Wheezy), I noticed that the system CPU usage was higher.  Running an strace on one of the Apache processes was giving me very little info: strace -c -p 10112 Process 10112 attached – interrupt to quit ^CProcess 10112 detached % time seconds usecs/call calls errors…

  • HHVM notes

    Impressive throughput improvements (>100%) with the app that I am working on. phpinfo() doesn’t output what you would expect. xhprof output_dir doesn’t get read from ini files, need to set that up in the constructor of XHProfRuns_Default. Set hhvm.server.thread_count to a high value (>=MaxRequestWorkers), otherwise a few slow MySQL queries could bring the server to…

  • Keepalived instance not entering FAILED state

    When a monitored interface goes down, the instance immediately enters FAILED state and the other instance gets into the MASTER state. But, if you have a script block to check – say you are monitoring HAProxy – and HAProxy goes down the MASTER will not enter FAILED state, unless you do this: Set the weight…