This is an automated email from the ASF dual-hosted git repository.
symat pushed a commit to branch branch-3.5
in repository https://gitbox.apache.org/repos/asf/zookeeper.git
The following commit(s) were added to refs/heads/branch-3.5 by this push:
new 755cb27 ZOOKEEPER-4220: Potential redundant connection attempts
during leader election
755cb27 is described below
commit 755cb27914589531b338f76cc7dae89775493ab4
Author: Mate Szalay-Beko <[email protected]>
AuthorDate: Tue Mar 9 17:07:55 2021 +0000
ZOOKEEPER-4220: Potential redundant connection attempts during leader
election
We have a logic in the server code, that would try to connect to an other
quorum member, based
on its server ID. We identify the address assigned to this ID first based
on the last committed
quorum configuration. If the connection attempt fails (or the server is not
known in the
committed configuration) then we try to find the address based on the last
proposed quorum
configuration. But we should do the second connection attempt, only if the
address in the
last proposed configuration differs from the address in the last committed
configuration.
Otherwise we would just retry to connect to the same address that failed
just right before.
In the current code we have a bug, because we compare the address object
references (use "!=")
instead of comparing the objects themselves (using "not equals"). In
certain edge cases (e.g.
when the last proposed and last committed addresses are the same, but the
address is unreachable)
this bug can lead to unnecessary retry of connection attempts. The normal
behaviour would be to
mark this connection attempt to be failed and wait for e.g. the next
election round or wait for
the other server to come online and initiate a connection to us.
Author: Mate Szalay-Beko <[email protected]>
Reviewers: Andor Molnar <[email protected]>, Damien Diederen
<[email protected]>
Closes #1631 from symat/ZOOKEEPER-4220-branch-3.5
---
.../java/org/apache/zookeeper/server/quorum/QuorumCnxManager.java | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/QuorumCnxManager.java
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/QuorumCnxManager.java
index 066ea9f..64673f5 100644
---
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/QuorumCnxManager.java
+++
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/QuorumCnxManager.java
@@ -722,9 +722,10 @@ public class QuorumCnxManager {
if (connectOne(sid, lastCommittedView.get(sid).electionAddr))
return;
}
- if (lastSeenQV != null && lastProposedView.containsKey(sid)
- && (!knownId || (lastProposedView.get(sid).electionAddr !=
- lastCommittedView.get(sid).electionAddr))) {
+ if (lastSeenQV != null
+ && lastProposedView.containsKey(sid)
+ && (!knownId
+ ||
!lastProposedView.get(sid).electionAddr.equals(lastCommittedView.get(sid).electionAddr)))
{
knownId = true;
LOG.debug("Server {} knows {} already, it is in the
lastProposedView", self.getId(), sid);
if (connectOne(sid, lastProposedView.get(sid).electionAddr))
