Chasing 503 Guru's

Per Buer perbu at
Thu Dec 2 16:49:11 CET 2010

On Thu, Dec 2, 2010 at 3:30 PM, Simon Males <sime at> wrote:
> On Fri, Dec 3, 2010 at 12:04 AM, Per Buer <perbu at> wrote:
>> On Thu, Dec 2, 2010 at 1:28 PM, Simon Males <sime at> wrote:
>>> Just wanted to share my understanding of tracking down 503 / Guru
>>> meditation errors.
>>> Steps:
>>> 1. Source the XID
>>> 2. Start varnishlog with -d
>>> 3. Search the output for the above mentioned XID
>>> 4. Hopefully the log entry will provide a clue
>>> Though how long do the shared memory logs exist?
>> Depends on how much traffic you have. On a busy site it should be a
>> minute or so. Try logging to disk and you notice how long 80MB (the
>> default) will last. It will give you an indication on how long the
>> shmlog lasts. However, the shmlog has some fixed length records so it
>> wastes a bit of space compared to the output to disk.
> So `varnishlog -w /tmp/varnishd.log` is self managing/rotating?

No. Not really. Varnish writes to a piece of shared memory. varnishlog
_reads_ from this memory. The memory segment is written to in a
circular buffer sort of way. So after a while the old content gets

> I performed the above with -d and it maintained at 58M. Without -d
> it's growing slowly then expected. 7M after 20 minutes of traffic.

> Where is logging to disk size specified?

Nowhere. You have to run varnishlog as a deamon to log to disk i a
permanent fasion.

Per Buer, Varnish Software
Phone: +47 21 98 92 61 / Mobile: +47 958 39 117 / Skype: per.buer

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