Re: Apache access slows down

"Simon Knight" <sknight_10@hotmail.com> writes:

> Tried the db_stat. The significant thing appears to be the huge
> number of locks; here is the diff of the -c, similar for the others.
>
> 1c1
> < 80 Last allocated locker ID.
> ---
>>432 Last allocated locker ID.
> 7,14c7,14
> < 0 Number of current locks.
> < 17 Maximum number of locks at any one time.
> < 0 Number of current lockers.
> < 17 Maximum number of lockers at any one time.
> < 0 Number of current lock objects.
> < 17 Maximum number of lock objects at any one time.
> < 6030 Total number of locks requested.
> < 6030 Total number of locks released.
> ---
>>14 Number of current locks.
>>65 Maximum number of locks at any one time.
>>17 Number of current lockers.
>>66 Maximum number of lockers at any one time.
>>14 Number of current lock objects.
>>51 Maximum number of lock objects at any one time.
>>3279992 Total number of locks requested.
>>3279970 Total number of locks released.
> 23,24c23,24
> < 0 The number of region locks granted after waiting.
> < 9423 The number of region locks granted without waiting.
> ---
>>39 The number of region locks granted after waiting.
>>3492667 The number of region locks granted without waiting.

That looks like before and after for an ra_dav checkout. What you
really want to do is compare a "fast" checkout with a "slow" one
i.e. zero before each checkout and compare the before-after diff for
the two checkouts. (The counts are cummulative and can be zeroed
using db_stat -cZ -h path/to/repo/db.)

> I left this test running until the locks were 5,000,000 or so and
> killed svn (keyboard interupt is never processed).

Large ra_dav checkout's use millions of region locks, so I don't think
5 million is the cause of the slowdown. (ra_dav is much more expensive
than ra_svn in terms of it's BDB lock usage, I see ra_dav using 5 or
10 times the number of locks that ra_svn uses.)

Your problem appears to duplicate issue 1563, if you agree it would be
useful if you added your experiences to the issue

http://subversion.tigris.org/issues/show_bug.cgi?id=1563

-- 
Philip Martin
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