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https://issues.apache.org/jira/browse/CURATOR-535?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17454352#comment-17454352
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Yao Zhang commented on CURATOR-535:
-----------------------------------
Hi [~randgalt] and [~thevern] ,
How about a solution which allows port, quorumPort and electionPort to be lazy
initialized with random unused port if not specified in InstanceSpec. Thus, the
available port will be allocated when TestingServer actually starts. The race
condition among threads can be alleviated. I am currently working on this
solution.
For multiple process running TestingServer, I suggest we use an external file
lock. The implementation may be cumbersome for TestingServer so it would be
better not to integrate it with TestingServer.
Correct me if I am wrong. Thanks.
> TestServer random port selection has a race condition
> -----------------------------------------------------
>
> Key: CURATOR-535
> URL: https://issues.apache.org/jira/browse/CURATOR-535
> Project: Apache Curator
> Issue Type: Bug
> Affects Versions: 4.2.0
> Environment: Operating System:
> Fedora 30 (amd64)
> JVM:
> openjdk version "1.8.0_212"
> OpenJDK Runtime Environment (build 1.8.0_212-b04)
> OpenJDK 64-Bit Server VM (build 25.212-b04, mixed mode)
> Reporter: Laverne Schrock
> Assignee: Jordan Zimmerman
> Priority: Minor
> Attachments: BugReproducer.java, log4j.properties
>
>
> When using one of the constructors for org.apache.curator.test.TestingServer
> that doesn't take a port number, the org.apache.curator.test.InstanceSpec
> that is constructed will chose random available ports to use. However,
> InstanceSpec only binds those ports during construction and then unbinds them
> so that they can be used when TestingServer.start() is called.
> This disconnect between port selection creates a race condition where some
> other process (or thread) could bind the port before TestingServer is started.
> I've seen this very rarely in our integration test suite that spins up and
> tears down TestingServer many times. I've attached a simple class for
> reproducing the issue. If you run it in an environment with log4j loaded and
> the attached log4j.properties, you should see output like the following
> (though it sometimes takes more iterations):
> {{completed iteration: 0}}
> {{completed iteration: 500}}
> {{2019-08-02 09:47:06 ERROR TestingZooKeeperServer:162 - From testing server
> (random state: false) for instance:
> InstanceSpec\{dataDirectory=/tmp/1564753624792-1, port=34707,
> electionPort=33621, quorumPort=45995, deleteDataDirectoryOnClose=true,
> serverId=1286, tickTime=-1, maxClientCnxns=-1, customProperties={},
> hostname=127.0.0.1} org.apache.curator.test.InstanceSpec@59c43d10}}
> {{java.net.BindException: Address already in use}}
> {{ at sun.nio.ch.Net.bind0(Native Method)}}
> {{ at sun.nio.ch.Net.bind(Net.java:433)}}
> {{ at sun.nio.ch.Net.bind(Net.java:425)}}
> {{ at
> sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)}}
> {{ at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)}}
> {{ at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:67)}}
> {{ at
> org.apache.zookeeper.server.NIOServerCnxnFactory.configure(NIOServerCnxnFactory.java:687)}}
> {{ at
> org.apache.zookeeper.server.ServerCnxnFactory.configure(ServerCnxnFactory.java:76)}}
> {{ at
> org.apache.curator.test.TestingZooKeeperMain.internalRunFromConfig(TestingZooKeeperMain.java:239)}}
> {{ at
> org.apache.curator.test.TestingZooKeeperMain.runFromConfig(TestingZooKeeperMain.java:132)}}
> {{ at
> org.apache.curator.test.TestingZooKeeperServer$1.run(TestingZooKeeperServer.java:158)}}
> {{ at java.lang.Thread.run(Thread.java:748)}}
> {{java.lang.IllegalStateException: Timed out waiting for watch removal}}
> {{ at
> org.apache.curator.test.TestingZooKeeperMain.blockUntilStarted(TestingZooKeeperMain.java:146)}}
> {{ at
> org.apache.curator.test.TestingZooKeeperServer.start(TestingZooKeeperServer.java:167)}}
> {{ at
> org.apache.curator.test.TestingServer.start(TestingServer.java:148)}}
> {{ at BugReproducer.main(BugReproducer.java:15)}}
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