[GitHub] trafficserver pull request #1514: Ensure 'service trafficserver stop’ is s...

[timbunce]

GitHub user timbunce opened a pull request:

    https://github.com/apache/trafficserver/pull/1514

    Ensure 'service trafficserver stop’ is synchronous under load on redhat

    Currently the service trafficserver stop command on redhat might return 
before ATS has exited.
    This is not good as it’s often followed by a start, which then fails.
    
    /etc/init.d/trafficserver does:
    
                action "Stopping ${TC_NAME}:" killproc -p $TC_PIDFILE $TC_DAEMON
                action "Stopping ${TM_NAME}:" killproc -p $TM_PIDFILE $TM_DAEMON
                action "Stopping ${TS_NAME}:" killproc -p $TS_PIDFILE $TS_DAEMON
    
    and killproc, as defined in /etc/rc.d/init.d/functions, with those 
arguments essentially does this:
    
        send SIGTERM
        wait up to 3 seconds for it to exit
        send SIGKILL
        wait 0.1 seconds then return an exit status indicating if the process 
still exists
    
    A SIGKILL signal always causes the death of a process but it’s not 
instantaneous. A process can take a long time to exit on a busy system for 
assorted reasons, including flushing dirty buffers to disk.
    
    So if the stop is immediately followed by a start, as it often is, the 
start may fail with an error like ‘port 80 in use’. This seems to be a 
common cause of restart failures on busy systems and frustrating manual 
hand-holding.
    
    Contrast this with the behaviour that /etc/init.d/trafficserver uses when 
run on Ubuntu… there it’ll wait up to 35 seconds.
    (It'll also use SIGQUIT instead of SIGTERM which seems odd).
    
    This PR makes /etc/init.d/trafficserver more reliable, and consistent, on 
redhat by adding `-d 35` to the killproc arguments so it'll wait for the 
daemons to stop on redhat for about as long as it does in ubuntu. Not perfect, 
but much better.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/timbunce/trafficserver patch-1

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/trafficserver/pull/1514.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #1514
    
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