SolrCloud with embedded ZooKeeper server says: “ZooKeeperServer not running”

Question

When I start my SolrCloud server, Solr opens a socket connection to the embedded ZooKeeper server but says: "ZooKeeperServer not running".

It doesn't state a reason.

How can I figure out why the ZooKeeper server isn't actually running?

2012-05-30 15:02:36.538 [main] INFO  org.apache.solr.cloud.SolrZkServer - STARTING EMBEDDED STANDALONE ZOOKEEPER SERVER at port 9983
2012-05-30 15:02:36.545 [Thread-14] INFO  o.a.z.server.ZooKeeperServerMain - Starting server
2012-05-30 15:02:36.552 [Thread-14] INFO  o.a.zookeeper.server.ZooKeeperServer - Server environment:zookeeper.version=3.3.3-1203054, built on 11/17/2011 05:47 GMT
... [snip] ...
2012-05-30 15:02:37.092 [main-SendThread()] INFO  org.apache.zookeeper.ClientCnxn - Opening socket connection to server localhost/127.0.0.1:9983
2012-05-30 15:02:37.097 [main-SendThread(localhost:9983)] INFO  org.apache.zookeeper.ClientCnxn - Socket connection established to localhost/127.0.0.1:9983, initiating session
2012-05-30 15:02:37.097 [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:9983] INFO  o.a.zookeeper.server.NIOServerCnxn - Accepted socket connection from /127.0.0.1:43635
2012-05-30 15:02:37.100 [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:9983] WARN  o.a.zookeeper.server.NIOServerCnxn - Exception causing close of session 0x0 due to java.io.IOException: ZooKeeperServer not running
2012-05-30 15:02:37.100 [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:9983] INFO  o.a.zookeeper.server.NIOServerCnxn - Closed socket connection for client /127.0.0.1:43635 (no session established for client)
2012-05-30 15:02:37.101 [main-SendThread(localhost:9983)] INFO  org.apache.zookeeper.ClientCnxn - Unable to read additional data from server sessionid 0x0, likely server has closed socket, closing socket connection and attempting reconnect

Answer 1

In my case specifically, it seemed that having a bunch of extra files in my conf/ directory was causing problems. Try to have the fewest amount of files necessary in that directory to ensure embedded Zookeeper running properly.