Alexander Marx wrote:

> Helen Borrie wrote:
>
>>Yup. The first user to select from that table after the huge deletes cops
>>the garbage collection.
>>
>>What you really need to do following these big deletes is to run a
>>sweep. It will slow things down for a while but it avoids landing one user
>>with the big cleanup. It will also be a good idea to run SET STATISTICS
>>after the sweep, as well, then log out, then log in again.
>>
>
>
> hm, ok i just tried that .. and got some interesting results:
>
> on the fbsd box:
>
> running gfix -sweep just after the delete magically finishes withing
> 10 seconds and after that the select also finishes within 8 secs.
> the gfix -sweep here also looks alot more "healthier" as it really
> produces a lot of physical disk i/o .. and almost no cpu load.
>
> great :-)
>
> but on the linux box (unfortunately the production server)
>
> gfix -sweep runs and runs and runs (and it looks like as it will
> again be running for the mysterious 50000 secs) ... :-(
>
> again almost no disk activity, just 100% cpu .. and ofcourse a select
> in parallel (started after the gfix was started) also never returns ..
>
>
> but, even if we just focus on the fbsd box ...
>
> it does not explain why the garbage collection, initiated
> by a client's select statement, takes >50000 seconds?!?
> (with 100% cpu; i'd think of garbage collection as a disk i/o
> bound process e.g. not constantly 100% cpu)
>
> so i still think we must be hitting a bug or somethin ...
>
> did you look at the stats from
> my last select? don't they look a bit "strange" for such a small
> database?
>
>
>
>>Ideally, you wouldn't set out to run this kind of major housekeeping on
>>regularly used tables during busy times.
>>
>
>
> hm, can i somehow disable that garbage-collection stuff on selects?
> setting sweep intervall to "0" does not seem to make a difference
> again results in a 50000 seconds "wait" on the first select ...
>

On Linux what kernel You have ? And do You have NTPL Firebird build for
this kernel if is required ? I'm not familiar with all this threads
support on Linux but as garbagge colletion occur in own thread this
could be related .


Regards
Boguslaw Brandys