Weirdness and graceful restart

[Hugues Alary]

Hi everyone,

I've been having a bug for the past few months where my varnishadm is
outputing wrong data. For example, typing:

$ varnishadm backend.list
available       0 boot
available       0 63952152-25bd-4ee7-b2f9-aa0244a05ccf
available       0 622f3e24-019e-48a3-8658-b310119947f4
available       0 fbd3fbc6-3a74-49a3-aeeb-100028da0ee6
available       0 0a37ec01-b01f-495f-9b0b-a95252080637
available       0 bd7624b2-3751-49fe-a745-3eadcad61289
available       0 29e08a95-56bc-4bfc-8985-a95e1c5db2de
available       0 319ed00f-a10f-4077-91e8-c0245f90f6cd
available       0 eaf3a4fe-c403-4e45-a6c8-32b81a1ddb68
available       0 c9cf84fa-447e-46ab-baa5-f165f21ba793
available       0 377cdfc8-ffce-4a6b-a361-c5b4b522edc3
available       0 9d2de965-1770-4859-8ea9-fb3886116a42
available       0 blogfixtmp
available       0 blog
available       0 blog1
available       0 t2
available       0 22850af6-7199-43ec-9730-5cf03cbcf94b
available       0 t4
available       0 t5
available       0 bbd996f1-c502-4977-88dd-b59985a31878
available       0 t10
available       0 t11
available       0 t12
available       0 t13
available       0 df946b95-2dee-407e-9434-92b9a33cbb59
available       0 thugues
available       0 t20
available       0 jared
available       0 hugues
available       0 hugues-2
available       0 hugues-3
available       0 hugues-4
available       0 redis-bug
available       0 f243afbb-ae48-4068-a702-5cf497fb53cb
available       0 hugues-random
available       0 redisbug
available       0 redisbug2
active         32 redisbug3

Typing it again would return something else, and so forth and so on.

It hasn't bothered me too much since I eventually get what I want, and
everything works, it's just the output that is messed up.

This never fixed itself, since varnish is super stable (85 days up since
last restart) and I haven't restarted it.

Now, it so happen that I really need to restart varnish, and I'm really
excited about doing it because it will fix the varnishadm problems.

*My question being: is there a way to restart varnish, without interrupting
current incoming requests?*

Thanks for your help!
-Hugues


ps: in case you're interested in the varnishadm bug, here's the useful
information:

Debian 7.3
Linux 3.10.23-xxxx-grs-ipv6-64 #1 SMP Mon Dec 9 19:06:18 CET 2013 x86_64
GNU/Linux
varnishd (varnish-3.0.5 revision 1a89b1f)

*How did the varnishadm bug happen? *
One day I typed, on my busy varnish:
varnishadm ban.list

After waiting for a while, I got some output.
Since that day, varnishadm output is wrong.
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