[CURATOR-507] PERSISTENT NODE ISSUE

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Cannot Reproduce
• Affects Version/s: 4.1.0
• Component/s: Recipes
• Assignee: Unassigned
• Reporter: Chevaris
• Created: 19/Feb/19 16:40
• Updated: 06/May/20 08:06
• Resolved: 06/May/20 08:06

Description

Hi there,

I am using Apache Curator 4.1.0 with Zk 3.4.10 (Open JDK 1.8)

openjdk version "1.8.0_191"

I am PersistentNode recipe and I am receiving this exception

 

java.lang.IllegalStateException: initial create has not been processed. Call waitForInitialCreate() to ensure.
at org.apache.curator.shaded.com.google.common.base.Preconditions.checkState(Preconditions.java:444)
at org.apache.curator.framework.recipes.nodes.PersistentNode.setData(PersistentNode.java:392)
at com.cheva.udr.sm.RemoteReporter.reportToRemote(RemoteReporter.java:67)
at com.cheva.udr.sm.RemoteReporter.lambda$2(RemoteReporter.java:84)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)

 

My class RemoteReporter.java (assumes that PersistentNode is thread safe)

// The class is final, and the attribute is private final so allow safe publication
private final Persistent pn;

Constrcutor()

{ ... PersistentNode pn = new PersistentNode(cf, CreateMode.EPHEMERAL, false, path, dataToReport()); }

// Class has also an start method
start()

{ ... 79 pn.start(); ... // Create new thread and execute the follwoing code 84 pn.waitForInitialCreate(1000, TimeUnit.DAYS); 85 pn.setData("XXx"); 86 statusCache.getListenable().addListener(listener); }

I was checking the PersistentNode code and the excepction happens because nodePath.get()==null variable. I am not 100% sure if the problem is in my code or in the recipe...

• My code is using the waitForinitial as suggested
• The recipe uses a CountDownLatch, but there are 2 different paths for the latch to be countDown (via initalisationComplete() method), and I am not sure that one of them assures that nodePath.get() != null

In this code snippet, you can see that the latch is countDown, but I am not sure that nodePath.set(whatever) is called, so I guess there could be a race condition

private final BackgroundCallback setDataCallback = new BackgroundCallback()
{

@Override
public void processResult(CuratorFramework dummy, CuratorEvent event)
throws Exception
{
//If the result is ok then initialisation is complete (if we're still initialising)
//Don't retry on other errors as the only recoverable cases will be connection loss
//and the node not existing, both of which are already handled by other watches.
if ( event.getResultCode() == KeeperException.Code.OK.intValue() )

{ //Update is ok, mark initialisation as complete if required. initialisationComplete(); }

else if ( event.getResultCode() == KeeperException.Code.NOAUTH.intValue() )
{
log.warn("Client does not have authorisation to write node at path {}", event.getPath());
authFailure.set(true);
}
}
};

Thanks in adavance for the help,

Evaristo