[Zookeeper-user] odd exceptions when using zookeeper

[Juan R. <Jua...@Su...>]

Hi, I am trying to become familiar with the zookeeper API and am seeing 
the following exceptions when attempting to create a node; any pointers 
as to where to look for their cause would be greatly appreciated.

AFAIK, I am not doing anything special.  I am running ZK standalone 
using JDK 1.6 and attempting to connect to it and create some nodes. 
Other than dataDir, I am using the configuration values in 
zoo_sample.cfg.  My attempt to create the nodes succeed sometimes, but 
more often than not, I get some fashion of "Session Expired" errors.  I 
am following com.yahoo.zookeeper.ZooKeeper.main() example and using 
5000ms for the client-side sessionTimeout.  Thanks in advance.

These happen in sequence:

java.io.IOException: TIMED OUT
         at 
com.yahoo.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:666)
com.yahoo.zookeeper.KeeperException: KeeperErrorCode = ConnectionLoss 
for /locks/
         at com.yahoo.zookeeper.ZooKeeper.create(ZooKeeper.java:244)
         at zookeeperclient.Main$Process.tryCreate(Main.java:142)
         at zookeeperclient.Main$Process.<init>(Main.java:87)
         at zookeeperclient.Main.main(Main.java:43)

java.io.IOException: Read error rc = -1 java.nio.DirectByteBuffer[pos=0 
lim=4 cap=4]
         at 
com.yahoo.zookeeper.ClientCnxn$SendThread.doIO(ClientCnxn.java:484)
         at 
com.yahoo.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:705)

java.lang.NullPointerException
         at com.yahoo.zookeeper.ClientCnxn.<init>(ClientCnxn.java:218)
         at com.yahoo.zookeeper.ClientCnxn.<init>(ClientCnxn.java:194)
         at com.yahoo.zookeeper.ZooKeeper.<init>(ZooKeeper.java:123)
         at zookeeperclient.Main$Process.tryCreate(Main.java:151)
         at zookeeperclient.Main$Process.<init>(Main.java:87)
         at zookeeperclient.Main.main(Main.java:43)
com.yahoo.zookeeper.KeeperException: KeeperErrorCode = SessionExpired 
for /locks/
         at com.yahoo.zookeeper.ZooKeeper.create(ZooKeeper.java:244)
         at zookeeperclient.Main$Process.tryCreate(Main.java:142)
         at zookeeperclient.Main$Process.<init>(Main.java:87)
         at zookeeperclient.Main.main(Main.java:43)