health check path doesn't change after VCL reload (2.0.6)

Caunter, Stefan scaunter at
Wed Jul 28 21:28:15 CEST 2010

Confirmed. Changing director load balance logic, backend membership, and
backend health checks requires a restart. Makes for exciting times if
you need to change .probe parameters on the fly when varnish thinks all
your backends are sick.


Stefan Caunter :: Senior Systems Administrator :: TOPS

e: scaunter at  ::  m: (416) 561-4871


From: varnish-misc-bounces at
[mailto:varnish-misc-bounces at] On Behalf Of Ken
Sent: July-28-10 9:48 AM
To: John Norman
Cc: Varnish misc
Subject: Re: health check path doesn't change after VCL reload (2.0.6)


I also recently confirmed that the backend specs aren't reset with a VCL
reload.  We had a backend timeout that was too short, but we had to do a
hard restart of all instances to pick up the change.  Not the end of the
world; worst case this might belong on the wiki.


The code to modify or respawn backend threads might be somewhat
complicated, but it's probably worth it, IMHO.




On Feb 24, 2010, at 1:25 PM, John Norman wrote:

No, only the former / old path.

I'm not super-troubled right now because a Varnish restart did pick up
the new path (but at the cost of my cache) -- but I'm a bit worried
about the next time I have to change it.

I will be changing the probe interval soon, so that will give me a
chance to reproduce the problem, if it even exists.

As a bit of background:

I automate the VCL update to multiple servers, when/if the VCL file has

Before the update, I also remove all of the inactive/old VCL's that are
sitting there.

Then I add the new one and "use" it.

When I observed in my backend logs the probes going to the old URLs, I
did check the "active" VCL on all systems, and they all showed the new

In any case, I will try to reproduce and will send the results.

One last thing: During the restart on one system, I observed the issue
reported here:


On Wed, Feb 24, 2010 at 4:18 PM, Poul-Henning Kamp <phk at>

In message <b6b8b6b71002241315w1c62022t1bf941d6f2cac0c7 at>,
John N

orman writes:

>Still, the VCL indicated as "active" had a different path for the

Hopefully both got probed ?


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by



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