Re: [Noffle-devel] [ noffle-Bugs-624357 ] SEGV during concurrent access.

[Mirko L. <mir...@we...>]

no...@so... wrote:
> Bugs item #624357, was opened at 2002-10-16 16:14

> Initial Comment:
> My noffle 1.1.2 crashed during fetch.  This happened
> crashed.  I could not find any core dump lying around.
It should be at /var/spool/noffle/core. Maybe the creation
of core files has been switched off by a ulimit command.

> This is not the only problem I had with concurrent
> access.  I am using an automated script to archive
> news.answers using NNTP STAT followed by a NEXT loop
> until it gets a 223.  Several times I read news while
> the script was running and it bailed out because it
> noticed the article ID had been reset to the first
> article in the group instead of being increased by NEXT
> to the next available article.

I added some additional Log_inf() calls to src/server.c:doNext(),
Server_flushCache(), changeToGrp() and src/lock.c:lockSignal().
Then I used two server processes to loop through the articles
of different groups in the aforementioned way.
Here's what I got (sorry for the long lines):

Oct 21 17:48:25 mliss noffle[7263]: Starting as server
Oct 21 17:48:25 mliss noffle[7264]: Starting as server
Oct 21 17:48:25 mliss noffle[7263]: ChangeToGrp 'de.alt.sysadmin.recovery' from 'de.alt.sysadmin.recovery'
Oct 21 17:48:25 mliss noffle[7263]: doNext(): artPtr 54853; grp de.alt.sysadmin.recovery
Oct 21 17:48:25 mliss noffle[7263]: doNext(): artPtr 54883; grp de.alt.sysadmin.recovery
[..proc 7263 iterates through the articles but is stopped by SIGUSR1
   after article 60439..]
Oct 21 17:48:26 mliss noffle[7263]: doNext(): artPtr 60438; grp de.alt.sysadmin.recovery
Oct 21 17:48:26 mliss noffle[7263]: lockSignal sig: 10
Oct 21 17:48:26 mliss noffle[7263]: doNext(): artPtr 60439; grp de.alt.sysadmin.recovery
Oct 21 17:48:26 mliss noffle[7263]: Server_flushCache() called
Oct 21 17:48:26 mliss noffle[7264]: ChangeToGrp 'de.alt.netdigest' from 'de.alt.netdigest'
Oct 21 17:48:26 mliss noffle[7264]: doNext(): artPtr 9222; grp de.alt.netdigest
Oct 21 17:48:26 mliss noffle[7264]: doNext(): artPtr 9223; grp de.alt.netdigest
[..proc 7264 iterates through the articles. Article 9316 is the last one..]
Oct 21 17:48:26 mliss noffle[7264]: doNext(): artPtr 9316; grp de.alt.netdigest
Oct 21 17:48:26 mliss noffle[7264]: Server_flushCache() called
Oct 21 17:48:26 mliss noffle[7263]: ChangeToGrp 'de.alt.sysadmin.recovery' from 'de.alt.sysadmin.recovery'
Oct 21 17:48:26 mliss noffle[7263]: doNext(): artPtr 54853; grp de.alt.sysadmin.recovery


I suppose the call of LoadGrpIfSelected() in src/server.c:doNext()
resets server.artPtr via changeToGrp(), because src/lock.c:lockSignal()
sets server.groupReady=FALSE via Server_flushCache().

I'm not sure how to get rid of that bug. Noffle's locking mechanism
still looks too weird for me to understand fully.


Mirko