On Oct 11, He Zhenxing wrote:
> Why is this patch for 5.0 only?
Because 5.1 has a different more complex fix -
ChangeSet@stripped, 2007-07-02 19:14:48+02:00, thek@adventure.(none) +10 -0
Bug#21074 Large query_cache freezes mysql server sporadically under heavy load
Invaldating a subset of a sufficiently large query cache can take a long time.
During this time the server is efficiently frozen and no other operation can
be executed. This patch addresses this problem by moving the locks which cause
the freezing and also by temporarily disable the query cache while the
invalidation takes place.
Regards / Mit vielen Grüssen,
> On 2007-08-29 18:30 +0400, Konstantin Osipov Wrote???
> > * kpettersson@stripped <kpettersson@stripped> [07/08/14 18:00]:
> > >
> > > ChangeSet@stripped, 2007-08-14 15:52:46+02:00, thek@adventure.(none) +1 -0
> > > Bug #21074 Large query_cache freezes mysql server sporadically under
> heavy load
> > >
> > > Invaldating a subset of a sufficiently large query cache can take a long
> > > During this time the server is efficiently frozen and no other operation
> > > be executed. This patch addresses this problem by setting a time limit
> > > how long time a dictionary access request can take before giving up on
> > > attempt. This patch does not work for query cache invalidations issued
> > > DROP, ALTER or RENAME TABLE operations.
> > >
> > > sql/sql_cache.cc@stripped, 2007-08-14 15:52:44+02:00, thek@adventure.(none)
> +27 -1
> > > Changed mutex locking to a timed spinn lock. If access to query cache
> > > takes "a long time" (currently more than 0.1 seconds) the system fall
> backs on
> > > ordinary statement execution.
> > As discussed on IRC:
> > since this patch is for 5.0 only, Shane/Sinisa should perform acceptance
> > tests.
> > After that, the patch is OK to push into 5.0 and null-merge into
> > 5.1.
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