[Varnish] #676: keeping varnishstat open will bring down server

Varnish varnish-bugs at varnish-cache.org
Tue Apr 13 15:27:50 CEST 2010

#676: keeping varnishstat open will bring down server
 Reporter:  ahongens     |       Owner:  phk  
     Type:  defect       |      Status:  new  
 Priority:  low          |   Milestone:       
Component:  varnishstat  |     Version:  trunk
 Severity:  minor        |    Keywords:       
 Hey guys,

 I've seen something I'd like to share with you, perhaps it could be seen
 as a bug in varnishstat.

 Yesterday I opened ssh sessions to my 4 balancers, to run some scripts,
 and then I opened varnishstat to monitor them. A while later I had to
 leave in a rush and closed my laptop's lid, and in that process killed my
 vpn tunnel and ssh sessions. However, the varnishstat process (apparently)
 keeps running. (FreeBSD 7.2 x64)

 Just a few hours ago (so around 16 hours later), I had one balancer die on
 my (become completely unresponsive, refuse connections to port 80). I
 immediately restarted varnishd, and I also saw a varnishstat instance eat
 100% cpu, which I killed.

 Now when I just looked on the other balancers, I see the varnishstat
 instance using up a lot of CPU (only one out of 4 cores though). See
 attached top.txt.

 So it seems running varnishstat for a long time, it will use more and more
 resources, and in my case, even cause varnishd to fail somehow (it could
 be a coincidence, but I don't think so).

 After killing varnishstat, load went back from 1.5 to 0.2, around the

Ticket URL: <http://www.varnish-cache.org/ticket/676>
Varnish <http://varnish-cache.org/>
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