[Openais] Checkpoint crash in aisexec
kjsmith at nortel.com
Tue Feb 15 08:47:47 PST 2005
Thanks for the response - I hear ya loud and clear - not good without
recovery. So, is there something that we could do to help you with this
recovery coding? If you had some type of design thoughts on how you wanted
checkpoint recovery to occur, maybe that is something we could help out
with. Just throwing this out there to see what you think.
From: Steven Dake [mailto:sdake at mvista.com]
Sent: Monday, February 14, 2005 2:17 PM
To: Smith, Kristen [NGC:B675:EXCH]; markh at osdl.org; openais at lists.osdl.org
Cc: Bajpai, Muni [NGC:B670:EXCH]
Subject: RE: [Openais] Checkpoint crash in aisexec
On Sat, 2005-02-12 at 08:08, Kristen Smith wrote:
> Thanks for the response.
> For recovery - what are the ramifications if we don't have recovery
> working 100%? What I see now is that when a node leaves the cluster
> and then rejoins, it receives evt messages, but it can take anywhere
> from 15seconds to minutes for evt messages sent from that node to
> reach the other applications. I handle this with some
Mark have you seen this issue?
> message retries which is ok in this startup case. However, are we in
> jeopardy in other cases that I am not considering? When running
> traffic the past few days and seeing periodic reconfigs, I don't seem
> to be losing messages when that occurs - I only see the lost messages
> when I actually kill a node and start it back up to rejoin the
What we have today is totally unacceptable because atleast for
checkpointing, there is no recovery. And Mark is waiting on my base code
for event recovery.
Definition of 100% working means if there is a failure during recovery, we
are guaranteed a consistent state. I think evt is pretty close to this
goal, although the checkpoint replication after merge has not been developed
yet. I can think of alot of easy ways to do this, but handling a failure
during the recovery phase makes it more difficult.
Definition of almost 100% is that recovery works properly if there are no
faults during recovery (ie: the merge process), but if there is a fault
during recovery (ie: reconfig) something could go awry.
We want consistently replicated data (the 100% case). 100% is probably past
your development window; the other case is within reach.
> -----Original Message-----
> From: Steven Dake [mailto:sdake at mvista.com]
> Sent: Friday, February 11, 2005 5:30 PM
> To: Smith, Kristen [NGC:B675:EXCH]
> Subject: RE: [Openais] Checkpoint crash in aisexec
> Ok well I doubt with 200 byte checkpoints there is a buffer overflow.
> Recovery will come after 188 is wrapped up. I think your two weeks
> window looks good for alpha-level recovery (ie: works most of the
> time). High quality production recovery will not hit your window for
> development (ie: works 100% of the time no matter what happens).
> On Fri, 2005-02-11 at 15:56, Kristen Smith wrote:
> > Steve,
> > The size of the checkpoints are ~200 bytes.
> > I agree, valgrind is an excellent tool. We will run it through and
> > if that shows anything.
> > I have tried this scenario maybe 30 times today (for various other
> > testing) and it happened maybe 10 times. For a while I could
> > with a given test about 5 times and then it hasn't happened again.
> > Sounds like defect-188 fixing is going well. May I ask how the
> > recovery work is going as well? (Don't mean to be pushy on that
> > - we have 2 more weeks of coding for our application left and I am
> > really hoping that we are able to put the new recovery code in
> > that time).
> > Thanks a bunch,
> > Kristen
> > -----Original Message-----
> > From: Steven Dake [mailto:sdake at mvista.com]
> > Sent: Friday, February 11, 2005 4:37 PM
> > To: Smith, Kristen [NGC:B675:EXCH]
> > Subject: Re: [Openais] Checkpoint crash in aisexec
> > how large are the read or write requests?
> > just a thought there could be some buffer overrun with larger
> > requests.
> > On Fri, 2005-02-11 at 14:55, Kristen Smith wrote:
> > > Steve,
> > >
> > > We are periodically seeing aisexec crash with the following trace:
> > >
> > > (gdb) bt
> > > #0 message_handler_req_lib_ckpt_checkpointclose
> > > (conn_info=0x0, message=0xb73fc008) at ckpt.c:1552
> > > #1 0x080494c2 in poll_handler_libais_deliver (handle=0,
> > fd=3,
> > > revent=134633824, data=0x89c2ad8,
> > > prio=0x89b2784) at main.c:578
> > > #2 0x08056e62 in poll_run (handle=0) at aispoll.c:386
> > >
> > >
> > > #3 0x080499ac in main (argc=1, argv=0xbfffcb64) at main.c:1003
> > >
> > > We have looked through the code but can't seem to figure out how
> > > conn_info is getting set to 0. Do you have any idea under what
> > > circumstances conn_info could be null when this function is
> > >
> > > This is happening when we have multiple nodes up and we kill one
> > > the active nodes. The standby node (which was reading checkpoints)
> > > must now become a writer, so it closes the checkpoint and this
> > > happens. Unfortunately, I can't reproduce this consistently - I
> > > finally got a core dump today. I don't recall ever seeing this
> > > the old code.
> > >
> > > Thanks,
> > > Kristen
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Openais mailing list
> > > Openais at lists.osdl.org
> > http://lists.osdl.org/mailman/listinfo/openais
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