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From John Nagro <jna...@hubspot.com>
Subject Re: BK servers in a funky state
Date Thu, 05 Apr 2012 14:53:12 GMT
Flavio -

I really appreciate your prompt response. Some quick background - we use
some of the hadoop technologies for storage, coordination, and processing.
Recently we wanted to add a write-ahead-log to our infrastructure so that
clients could record "transactions" prior to executing them - such as
updates going to an API or processing of an event. I've written a set of
tools that use BK as a generic write-ahead-logger. Clients (using zookeeper
for coordination) can create named write ahead logs with custom chunking
(how frequently a new ledger is created - based on size/time). Once a
ledger has rolled-over (or a client crashes), a persister (monitoring ZK)
reads that ledger and persists it to S3/HDFS as hadoop sequence files where
a map-reduce process can reconcile it. The ledger is then deleted from BK.
This is all done using ZK in a fashion where (hopefully) once a client has
written any data to the ledger it will always end up on S3/HDFS (via BK)
even if the client crashes (the persister will always know which ledger
belongs to which log and which ledgers are currently in use).

Does that sound like an appropriate use of BK? It seemed like a natural fit
as a durable storage solution until something can reliably get it to a
place where it would ultimately be archived and could be
reprocessed/reconciled (S3/HDFS).

As for the bug fix you mentioned, this gist shows the logs from the cut i
made this morning:

https://gist.github.com/aea874d89b28d4cfef31

As you can see, there are still some exceptions and error messages that
repeat (forever). This is the newest cut available on github, last commit
is:

commit f694716e289c448ab89cab5fa81ea0946f9d9193
Author: Flavio Paiva Junqueira <fpj@apache.org>
Date:   Tue Apr 3 16:02:44 2012 +0000

BOOKKEEPER-207: BenchBookie doesn't run correctly (ivank via fpj)

git-svn-id:
https://svn.apache.org/repos/asf/zookeeper/bookkeeper/trunk@130900713f79535-47bb-0310-9956-ffa450edef68


What are your thoughts? Thanks!

-John


On Thu, Apr 5, 2012 at 10:10 AM, Flavio Junqueira <fpj@yahoo-inc.com> wrote:

> Hi John, Let's see if I can help:
>
> On Apr 5, 2012, at 3:19 PM, John Nagro wrote:
>
> Hello -
>
> I've been hitting Ivan up for advice about a bookkeeper project of mine. I
> recently ran into another issue and he suggested I inquire here since he is
> traveling.
>
> We've got a pool of 5 BK servers running in EC2. Last night they got into
> a funky state and/or crashed - unfortunately the log with the original
> event got rotated (that has been fixed). I was running a cut of
> 4.1.0-SNAPSHOT sha 6d56d60831a63fe9520ce156686d0cb1142e44f5 from Wed Mar 28
> 21:57:40 2012 +0000 which brought everything up to BOOKKEEPER-195. That
> build had some bugfixes over 4.0.0 that I was originally running (and a
> previous version before that).
>
>
> Is there anything else you can say about your application, like how fast
> you're writing and how often you're rolling ledgers maybe? Are you deleting
> ledgers at all?
>
>
> When I restart the servers after the incident this is what the logs looked
> like:
>
> https://gist.github.com/f2b9c8c76943b057546e
>
> Which contain a lot of errors - although it appears the servers come up (i
> have not tried to use the servers yet). Although I don't have the original
> stack that caused the crash, the logs from recently after the crash
> contained a lot of this stack:
>
> 2012-04-04 21:04:58,833 - INFO
> [GarbageCollectorThread:GarbageCollectorThread@266] - Deleting entryLogId
> 4 as it has no active ledgers!
> 2012-04-04 21:04:58,834 - ERROR [GarbageCollectorThread:EntryLogger@188]
> - Trying to delete an entryLog file that could not be found: 4.log
> 2012-04-04 21:04:59,783 - WARN  [NIOServerFactory-3181:NIOServerFactory@129]
> - Exception in server socket loop: /0.0.0.0
>
> java.util.NoSuchElementException
>         at java.util.LinkedList.getFirst(LinkedList.java:109)
>         at
> org.apache.bookkeeper.bookie.LedgerCacheImpl.grabCleanPage(LedgerCacheImpl.java:458)
>         at
> org.apache.bookkeeper.bookie.LedgerCacheImpl.putEntryOffset(LedgerCacheImpl.java:165)
>         at
> org.apache.bookkeeper.bookie.LedgerDescriptorImpl.addEntry(LedgerDescriptorImpl.java:93)
>         at
> org.apache.bookkeeper.bookie.Bookie.addEntryInternal(Bookie.java:999)
>         at org.apache.bookkeeper.bookie.Bookie.addEntry(Bookie.java:1034)
>         at
> org.apache.bookkeeper.proto.BookieServer.processPacket(BookieServer.java:359)
>         at
> org.apache.bookkeeper.proto.NIOServerFactory$Cnxn.readRequest(NIOServerFactory.java:315)
>         at
> org.apache.bookkeeper.proto.NIOServerFactory$Cnxn.doIO(NIOServerFactory.java:213)
>
>         at
> org.apache.bookkeeper.proto.NIOServerFactory.run(NIOServerFactory.java:124)
>
>
> This looks like what we found and resolved here:
>
> https://issues.apache.org/jira/browse/BOOKKEEPER-198
>
>
> This morning I upgraded to the most recent cut -
> sha f694716e289c448ab89cab5fa81ea0946f9d9193 made on Tue Apr 3 16:02:44
> 2012 +0000 and restarted. That did not seem to correct matters, although
> the log has slightly different error messages:
>
> https://gist.github.com/aea874d89b28d4cfef31
>
> Does anyone know whats going on? How i can correct these errors? Are the
> machines in an okay state to use?
>
>
> It sounds like we have resolved it in 198, so if you're using a recent
> cut, you shouldn't observe this problem anymore. But, if it does happen
> again, it would be great to try to find a way to reproduce it so that we
> can track the bug... assuming it is a bug.
>
> -Flavio
>
>
>

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