Chris:
I have defined:
private static final int MAX_ZK_CONNECT_ATTEMPTS = 400;
private static final long ZK_CONNECT_WAIT = 5; // Milliseconds
so, two seconds, but I have also tried with ZK_CONNECT_WAIT = 500 (two
hundred seconds). getState always returned CONNECTING. I can play with
the async notification, but it really doesn't fit my application very
well. Is there any additional server or client tracing that can be
enabled to get a better sense of what is going on?
Chris
IBM Tivoli Systems
Research Triangle Park, NC
(919) 224-2240
Internet: [email protected]
From: Chris Nauroth <[email protected]>
To: "[email protected]" <[email protected]>
Date: 07/24/2015 06:19 PM
Subject: Re: ZooKeeper Class Will Not Connect
Hello Chris,
Thank you for the detailed repro steps describing which versions work and
which versions don't work. I tested your code sample against a 3.4.6
build, and it worked consistently for me. My only thought is that perhaps
the MAX_ZK_CONNECT_ATTEMPTS and ZK_CONNECT_WAIT constants are set such
that the polling loop exits before the connection completes. Perhaps a
subtle timing difference in the newer versions is just now exposing this.
The typical pattern for connection establishment is to rely on the
ZooKeeper client's asynchronous event notification instead of a polling
loop. See below for a code sample that initiates the connection and then
waits for the SyncConnected event. The ZooKeeper programmer's guide and
example program docs have a more detailed discussion of this.
http://zookeeper.apache.org/doc/r3.4.6/zookeeperProgrammers.html
http://zookeeper.apache.org/doc/r3.4.6/javaExample.html
Could you please try running this against your 3.4.6 cluster? I'd be
curious to see if the connection completes for you. This would also give
you a sense for how long connection establishment is taking and whether or
not that's in line with your definitions of MAX_ZK_CONNECT_ATTEMPTS and
ZK_CONNECT_WAIT.
I hope this helps.
class Main implements Watcher {
private final CountDownLatch connectLatch;
private final ZooKeeper zk;
public static void main(final String[] args) throws Exception {
String hostPort = args[0];
Main main = new Main(hostPort);
main.awaitConnection();
System.out.println("Exiting.");
}
private Main(String hostPort) throws Exception {
this.connectLatch = new CountDownLatch(1);
this.zk = new ZooKeeper(hostPort, 3000, this);
}
private void awaitConnection() throws InterruptedException {
this.connectLatch.await();
System.out.println("Connection has completed.");
}
@Override
public void process(WatchedEvent event) {
System.out.println("Received event: " + event);
if (event.getType() == Event.EventType.None) {
switch (event.getState()) {
case SyncConnected:
this.connectLatch.countDown();
break;
}
}
}
}
--Chris Nauroth
On 7/24/15, 9:16 AM, "Chris Barlock" <[email protected]> wrote:
>Ran some more tests. My code works fine up through ZK 3.4.2, but then
>fails with 3.4.3. I did have to add the following to the Import-Package
>list in the ZK MANIFEST.MF:
>
>org.slf4 j,javax.security.auth.login,javax.security.sasl
>
>I could really use some help here, ZK folks! Is my code incorrect with
>newer versions of ZK, or is ZK broken?
>
>Chris
>
>
>
>
>
>From: Chris Barlock/Raleigh/IBM@IBMUS
>To: [email protected]
>Date: 07/23/2015 09:34 PM
>Subject: Re: ZooKeeper Class Will Not Connect
>
>
>
>I tried the 3.5.0 alpha build to see if it made any difference. It did
>not.
>
>But, I had to hack the MANIFEST.MF file in the JAR because the
>"3.50-alpha" version fails tests in OSGi bundles that import the ZK
>classes which have something like:
>
>version="[3.2,4)"
>
>I suggest that if you want to name the JAR "3.50-alpha" that all the
>internals just use a version of 3.50.
>
>Chris
>
>IBM Tivoli Systems
>Research Triangle Park, NC
>(919) 224-2240
>Internet: [email protected]
>
>
>
>From: Chris Barlock/Raleigh/IBM@IBMUS
>To: [email protected]
>Date: 07/23/2015 01:37 PM
>Subject: ZooKeeper Class Will Not Connect
>
>
>
>We are attempting to upgrade from Kafka 0.8.0, which includes ZK 3.3.4 to
>Kafka 0.8.2.1 with ZK 3.4.6. My code which attempts to connect to ZK is
>pretty straightforward:
>
> try {
> ZooKeeper zk = new ZooKeeper(connectString,
sessionTimeout
>, this);
> int connectAttempts = 0;
>
> while (!zk.getState().isConnected() && connectAttempts <
>MAX_ZK_CONNECT_ATTEMPTS) {
> try {
> Thread.sleep(ZK_CONNECT_WAIT);
> } catch (InterruptedException e) {
> // Ignore
> }
> connectAttempts++;
> }
> } catch (IOException e) {
> trace.exception(CLASS_NAME, methodName, e);
> }
>
>With some additional tracing, States is always CONNECTING. Has something
>changed with 3.4.6 about how I should connect to the server? I can
>connect just fine with the zookeeper-shell.sh that Kafka ships. This
>code
>
>
>always runs on the same system as ZK, so the connectString is always
>"localhost:2181"
>
>Chris
>
