Ben,
I am able to run algorithm 3 successfully sometimes, though frequently
the servers deadlock in QuorumCnxManager:initiateConnection on
s.read(msgBuffer) when reading the challenge from the peer.
Calls to initiateConnection and receiveConnection are synchronized, so
only one or the other can be executing at a time. This prevents two
connections from opening between the same pair of servers.
However, it seems that this leads to deadlock, as in this scenario:
A (initiate --> B)
B (initiate --> C)
C (initiate --> A)
initiateConnection can only complete when receiveConnection runs on
the remote peer and answers the challenge. If all servers are blocked
in initiateConnection, receiveConnection never runs and leader
election halts.
Looking forward to your thoughts.
Thanks,
Austin
On Sep 2, 2008, at 10:14 AM, Benjamin Reed wrote:
Austin,
Could you try using the new leader election algorithm? You need to set
the algorithm type to 3 and you also need to set the election port
(TCP)
to be used.
See http://zookeeper.wiki.sourceforge.net/ZooKeeperConfiguration for
more details.
ben
-----Original Message-----
From: Austin Shoemaker [mailto:[EMAIL PROTECTED]
Sent: Tuesday, September 02, 2008 9:57 AM
To: [email protected]
Subject: Leader election stalled
Hi,
We have run into a situation where killing the leader results in
followers
perpetually trying to reelect that leader.
We have 11 zookeeper (2.2.1 from SF.net) servers and 256 clients
connecting
at random. We kill the leader and observe the impact, monitoring a
script
that repeatedly prints the responses to "ruok" and "stat". All servers
except the killed leader respond with "imok" and "ZooKeeperServer not
running", respectively.
About half of the time, each remaining server gets into a loop of
failing to
connect to the killed leader and then reelecting the killed leader.
Here is an example log, which is representative of similar logs on the
other
servers. We additionally logged connectivity during leader election.
If
anyone would like complete logs, let me know.
Thanks,
Austin Shoemaker
WARN - [QuorumPeer:[EMAIL PROTECTED] - FOLLOWING
*WARN - [QuorumPeer:[EMAIL PROTECTED] - Following /10.50.65.22:2889*
ERROR - [QuorumPeer:[EMAIL PROTECTED] - FIXMSG
java.net.ConnectException: Connection refused
*
.... cont'd ....*
ERROR - [QuorumPeer:[EMAIL PROTECTED] - FIXMSG
java.lang.Exception: shutdown Follower
at
com.yahoo.zookeeper.server.quorum.Follower.shutdown(Follower.java:364)
at
com.yahoo.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:403)
WARN - [QuorumPeer:[EMAIL PROTECTED] - LOOKING
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.22:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.22:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.21:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.21:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.12:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.12:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.11:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.11:2888
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.12:2890
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.12:2890
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.11:2890
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.11:2890
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.22:2889
*WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Exception occurred
when
sending / receiving packet to / from /10.50.65.22:2889
java.net.SocketTimeoutException: Receive timed out
*WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to
/10.50.65.21:2890
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.21:2890
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.21:2889
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.21:2889
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.12:2889
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.12:2889
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Sending election
packet
to /
10.50.65.11:2889
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Received response
from /
10.50.65.11:2889
WARN - [QuorumPeer:[EMAIL PROTECTED] - Election tally:
WARN - [QuorumPeer:[EMAIL PROTECTED] - 8 -> 1
WARN - [QuorumPeer:[EMAIL PROTECTED] - 4 -> 1
WARN - [QuorumPeer:[EMAIL PROTECTED] - 7 -> 8
WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Election complete,
result.winner = 7
*WARN - [QuorumPeer:[EMAIL PROTECTED] - ----> Election complete,
address
= /10.50.65.22:2889
WARN - [QuorumPeer:[EMAIL PROTECTED] - FOLLOWING
WARN - [QuorumPeer:[EMAIL PROTECTED] - Following /10.50.65.22:2889
ERROR - [QuorumPeer:[EMAIL PROTECTED] - FIXMSG
java.net.ConnectException: Connection refused
* at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at
java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:519)
at
com
.yahoo.zookeeper.server.quorum.Follower.followLeader(Follower.java:13
3)
at
com.yahoo.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:399)
