RE: [HACKERS] postgresql-v6.5beta2.tar.gz ...

> -----Original Message-----
> From: root@sunpine.krs.ru [mailto:root@sunpine.krs.ru]On Behalf Of Vadim
> Mikheev
> Sent: Monday, June 07, 1999 7:49 PM
> To: Hiroshi Inoue
> Cc: The Hermit Hacker; pgsql-hackers@postgreSQL.org
> Subject: Re: [HACKERS] postgresql-v6.5beta2.tar.gz ...
> 
> 
> Hiroshi Inoue wrote:
> > 
> > >
> > > Hiroshi, please run your test. You'll get NOTICEs instead of ERRORs.
> > 
> > I have run my test and got the following NOTICEs.
> > 
> > NOTICE:  Child itemid in update-chain marked as unused - can't
> > continue vc_rpfheap
> 
> I'm still getting troubles when running your test due to
> 
> 1. bug in cache invalidation code: when we invalidate relcache
>    we forget to free MdfdVec in md.c!
> 
>    Vacuum invalidates a relation tuple in pg_class and concurrent
>    xactions invalidate corresponding relcache entry, but don't
>    free MdfdVec and so allocate new one for the same relation

I have noticed the same thing   But at that point my concern was 
truncation of segmented relations. AFAIC concurrent xactions 
invalidate relcache entry when StartTransaction() or Command-
CounterIncrement() is called.  Unfortunately vacuum couldn't stop 
other sessions from executing StartTransaction() nor Command-
CounterIncrement().

>    more and more. Each MdfdVed requires own fd.c:Vfd entry -> below
> 
> 2. fd.c:pg_nofile()->sysconf(_SC_OPEN_MAX) returns in FreeBSD 
>    near total number of files that can be opened in system
>    (by _all_ users/procs). With total number of opened files
>    ~ 2000 I can run your test with 10-20 simultaneous
>    xactions for very short time, -:)
>

I have remembered another thing.
Someone has already reported to ML in Japan and I was able to 
find the cause easily thanks to him.

vacuum calls open() directly to create pg_vlock file.
Sometimes I was not able to open the file because of the lack of 
file descriptors().
FileNameOpenFile()/FileClose() etc should be called instead of 
open()/close() etc ?

Regards.

Hiroshi Inoue
Inoue@tpf.co.jp