Re: Problem with insert delayed thread. Perhaps a linuxthread problem ?

[Antoine]

Hi,

> As my use of MySQL (in terms of queries per second) has increased over
> the years, I'm come to find all sorts of issues with insert delayed.
> Including this one you mention (which is a variation of other
> incarnations) which was in 3.23.x. Eventually we rewrote things to not
> use or need it and haven't looked back.
> 
> Debugging will not be fun. As I remember, it only occurred over a
> certain QPS threshold, which means full debugging will slow the server
> to a point that it won't happen. Yuck!

I had the same problem (with 3.23.x source distribution under Linux 2.4.x)
and finally gave up using INSERT DELAYED under high pressure. It's really
a QPS-related problem because my application doesn't have much concurrency
in itself (only one writing client and very few reading clients - but the
writing client sometimes keeps sending queries to MySQL as it receives lots
of data to process & store).

The shame is, DELAYED INSERTs are really only useful under high load
(because then inserts are batched together). Well....

Jocelyn, if you already use DELAY_KEY_WRITE, maybe DELAYED isn't much
useful after all ? With an async filesystem (default under Linux) and
noatime set on the partition, it may get together quite well...
(as I've seen in your query results, is it for the well-known web site
hardware.fr ?)

Regards

Antoine.