[CURATOR-551] Curator client always call updateServerList with original serverList value, not the ones updated by EnsembleTracker

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.2.0
• Fix Version/s: 4.3.0
• Component/s: Client
• Assignee: Jordan Zimmerman
• Reporter: kelgon wu
• Created: 09/Dec/19 02:55
• Updated: 10/May/23 12:46
• Resolved: 12/Feb/20 22:08

Description

Whenever ConnectionState.handleNewConnectionString is triggered, the value of  newConnectionString is always the value used to construct the FixedEnsembleProvider

 

in ConnectionState:

String newConnectionString = zooKeeper.getNewConnectionString();
if ( newConnectionString != null ) {
    handleNewConnectionString(newConnectionString);
}

...

if ( ensembleProvider.updateServerListEnabled() ) {
    zooKeeper.updateServerList(newConnectionString);
} else {
    reset();
}

 

in HandleHolder:

String getNewConnectionString() {
    String helperConnectionString = (helper != null) ? helper.getConnectionString() : null;
    return ((helperConnectionString != null) && !ensembleProvider.getConnectionString().equals(helperConnectionString)) ? helperConnectionString : null;
}

code above shows that the newConnectionString is provided by helper.getConnectionString(), which only instantiated on first call of getZookeeper:

@Override
public ZooKeeper getZooKeeper() throws Exception
{
    synchronized(this)
    {
        if ( zooKeeperHandle == null )
        {
            connectionString = ensembleProvider.getConnectionString();
            zooKeeperHandle = zookeeperFactory.newZooKeeper(connectionString, sessionTimeout, watcher, canBeReadOnly);
        }
...

 

As a result, when I reconfig zookeeper serverList, curator client always call updateServerList with the initial value, not the ones I just reconfigured

Issue Links

• fixes: CURATOR-7 Session ids not preserved if EnsembleProvider has changed the ensemble
• is related to: CURATOR-570 Excessive calls to ZooKeeper.updateServerList (which can result in session death)
• links to: GitHub Pull Request #345