[ZODB-Dev] "tid to old for invq" in zeo server logs?

[Jim Fulton]

On Mon, Oct 19, 2009 at 6:38 AM, Chris Withers <chris at simplistix.co.uk> wrote:
> Hi All,
>
> I saw a few entries like these in the event log of a storage server that
> stopped responding for a couple of minutes:
>
> INFO ZEO.StorageServer (30332) tid to old for invq 252618838173181593 <
> 252618856850589832
> ------
> INFO ZEO.StorageServer (30332) tid to old for invq 252618838177204172 <
> 252618856850589832
>
> What do these mean?

It means that the server wasn't able to provide "quick" invalidations
because a client was disconnected too long.  The message isn't very
well worded, even aside from the misspelling.

Normally, in this situation, a client would then perform a full cache
verification, which puts lots of pressure on the server, possibly
making it unresponsive.  There's a client option
"drop-cache-rather-than-verify" that can prevent this. Arguably, this
is a "don't be stupid" option that should be enabled by default.

Jim

-- 
Jim Fulton