[
https://issues.apache.org/jira/browse/CURATOR-573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17127410#comment-17127410
]
Viniti commented on CURATOR-573:
--------------------------------
Sure, I will change the code as suggested(below are the changes). Please keep
this bug opened for 2 days so that I can test if this change fixes the leader
election issue. I will close this bug after that. Thanks for your time and help.
{code:java|title=takeLeadership()|borderStyle=solid}
@Override
public void takeLeadership(CuratorFramework client) throws Exception {
// we are now the leader. This method should not return until we want
to relinquish leadership
final int waitSeconds = (int) (5 * Math.random()) + 1;
LOGGER.info(name + " is now the leader. Waiting " + waitSeconds + "
seconds...");
LOGGER.debug(name + " has been leader " + leaderCount.getAndIncrement()
+ " time(s) before.");
//do leader task
try {
while (true) {
Thread.sleep(TimeUnit.SECONDS.toMillis(waitSeconds));
}
} catch (InterruptedException e) {
LOGGER.error(name + " was interrupted.");
//application code cleanup for leader tasks
Thread.currentThread().interrupt();
}
}
{code}
> No leader is getting selected intermittently
> --------------------------------------------
>
> Key: CURATOR-573
> URL: https://issues.apache.org/jira/browse/CURATOR-573
> Project: Apache Curator
> Issue Type: Bug
> Components: Apache, Framework, Recipes
> Affects Versions: 4.0.1
> Reporter: Viniti
> Priority: Critical
>
> I am using Apache Curator Leader Election Recipe :
> https://curator.apache.org/curator-recipes/leader-election.html in my
> application.
> Zookeeper version : 3.5.7
> Curator : 4.0.1
> Below are the sequence of steps:
> 1. Whenever my tomcat server instance is getting up, I create a single
> CuratorFramework instance(single instance per tomcat server) and start it :
> {code:title=StartUp Code|borderStyle=solid}
> CuratorFramework client = CuratorFrameworkFactory.newClient(connectionString,
> retryPolicy);
> client.start();
> if(!client.blockUntilConnected(10, TimeUnit.MINUTES)){
> LOGGER.error("Zookeeper connection could not establish!");
> throw new RuntimeException("Zookeeper connection could not establish");
> }
> {code}
> 2. Create an instance of LSAdapter and start it:
> {code:title=LSAdapter initializing|borderStyle=solid}
> LSAdapter adapter = new LSAdapter(client, <some_metadata>);
> adapter.start();
> {code}
> Below is my LSAdapter class :
> {code:title=LSAdapter.java|borderStyle=solid}
> public class LSAdapter extends LeaderSelectorListenerAdapter implements
> Closeable {
> //<Class instance variables defined>
> public LSAdapter(CuratorFramework client, <some_metadata>) {
> leaderSelector = new LeaderSelector(client,
> <path_to_be_used_for_leader_election>, this);
> leaderSelector.autoRequeue();
> }
> public void start() throws IOException {
> leaderSelector.start();
> }
> @Override
> public void close() throws IOException {
> leaderSelector.close();
> }
> @Override
> public void takeLeadership(CuratorFramework client) throws Exception {
> final int waitSeconds = (int) (5 * Math.random()) + 1;
> LOGGER.info(name + " is now the leader. Waiting " + waitSeconds + "
> seconds...");
> LOGGER.debug(name + " has been leader " + leaderCount.getAndIncrement() + "
> time(s) before.");
> while (true) {
> try {
> Thread.sleep(TimeUnit.SECONDS.toMillis(waitSeconds));
> //do leader tasks
> } catch (InterruptedException e) {
> LOGGER.error(name + " was interrupted.");
> //cleanup
> /*Here, code is creating a znode. If client 's current state is CLOSED, this
> line will throw exception resulting in takeLeadership() exit. Else if, client
> state is STARTED, znode should be created. In case when LSAdaptor.close() is
> called, the client state will always be CLOSED at this line, and an exception
> is expected to be thrown.*/
> //This line will always throw exception when client state is "CLOSED" and
> because of which takeLeadership will exit
> ZookeeperUtil.createEphemeral(client, <some_path>);
> Thread.currentThread().interrupt();
> } finally {
> }
> }
> }
> }
> {code}
> 4. When server instance is getting down, close LSAdapter instance(which
> application is using) and close CuratorFramework client created
> {code:title=PreDestroy code|borderStyle=solid}
> CloseableUtils.closeQuietly(lsAdapter);
> curatorFrameworkClient.close();
> {code}
> The issue I am facing is that at times, when server is restarted, no leader
> gets elected. I checked that by tracing the log inside takeLeadership(). I
> have two tomcat server instances with above code, connecting to same
> zookeeper quorum and most of the times one of the instance becomes leader but
> when this issue happens, both of them becomes follower. Please suggest what
> am I doing wrong.
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
