Just a small addition: In my opinion the patch could really boil down to
add a
quorumServer.electionAddr = new
InetSocketAddress(electionAddr.getHostName(), electionAddr.getPort());
in the catch(IOException e) clause of the connectOne() method of the
QuorumCnxManager. In addition on should perhaps make the electionAddr
field in the QuorumPeer.QuorumServer class volatile to prevent races.
I haven't checked this change yet fully for implications but doing a
quick test on some machines at least showed it would solve our use case.
What do the more expert users / maintainers think - is it even
worthwhile to go that route?
Am 14.03.2012 17:04, schrieb ext Christian Ziech:
LEt me describe our upcoming use case in a few words: We are planning
to use zookeeper in a cloud were typically nodes come and go
unpredictably. We could ensure that we always have a more or less
fixed quorum of zookeeper servers with a fixed set of host names.
However the IPs associated with the host names would change every time
a new server comes up. I browsed the code a little and it seems right
now that the only problem is that the zookeeper server is remembering
the resolved InetSocketAddress in its QuorumPeer hash map.
I saw that possibly ZOOKEEPER-107 would also solve that problem but
possibly in a more generic way than actually needed (perhaps here I
underestimate the impact of joining as a server with an empty data
directory to replace a server that previously had one).
Given that - from looking at ZOOKEEPER-107 - it seems that it will
still take some time for the proposed fix to make it into a release,
would it make sense to invest time into a smaller work fix just for
this "replacing a dropped server without rolling restarts" use case?
Would there be a chance that a fix for this makes it into the 3.4.x
branch?
Are there perhaps other ways to get this use case supported without
the need for doing rolling restarts whenever we need to replace one of
the zookeeper servers?
--
*NOKIA*
*Christian Ziech*
Senior Software Developer
Context Based Services
Services & Software
Mobile: +4915155155740
Fax: +493044676555
eMail: christian.zi...@nokia.com
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