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https://issues.apache.org/jira/browse/ZOOKEEPER-737?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13103862#comment-13103862
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Patrick Hunt commented on ZOOKEEPER-737:
----------------------------------------
which version of nc are you using? The newer (ubuntu pkging) openbsd or
"traditional"? You might try both.
We got it to work well with traditional, then ubuntu went and made openbsd the
default:
{noformat}
phunt@ubuntu:~$ nc
This is nc from the netcat-openbsd package. An alternative nc is available
in the netcat-traditional package.
usage: nc [-46DdhklnrStUuvzC] [-i interval] [-P proxy_username] [-p source_port]
[-s source_ip_address] [-T ToS] [-w timeout] [-X proxy_protocol]
[-x proxy_address[:port]] [hostname] [port[s]]
phunt@ubuntu:~$ ls /bin/nc.*
/bin/nc.openbsd* /bin/nc.traditional*
{noformat}
> some 4 letter words may fail with netcat (nc)
> ---------------------------------------------
>
> Key: ZOOKEEPER-737
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-737
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.3.0
> Reporter: Patrick Hunt
> Assignee: Mahadev konar
> Priority: Blocker
> Fix For: 3.3.1, 3.4.0
>
> Attachments: ZOOKEEPER-737.patch, ZOOKEEPER-737.patch,
> ZOOKEEPER-737.patch, ZOOKEEPER-737.patch, ZOOKEEPER-737.patch,
> ZOOKEEPER-737.patch, ZOOKEEPER-737.patch
>
>
> nc closes the write channel as soon as it's sent it's information, for
> example "echo stat|nc localhost 2181"
> in general this is fine, however the server code will close the socket as
> soon as it receives notice that nc has
> closed it's write channel. if not all the 4 letter word result has been
> written back to the client yet, this will cause
> some or all of the result to be lost - ie the client will not see the full
> result. this was introduced in 3.3.0 as part
> of a change to reduce blocking of the selector by long running 4letter words.
> here's an example of the logs from the server during this
> echo -n stat | nc localhost 2181
> 2010-04-09 21:55:36,124 - INFO
> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn$Factory@251] -
> Accepted socket connection from /127.0.0.1:42179
> 2010-04-09 21:55:36,124 - INFO
> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@968] - Processing
> stat command from /127.0.0.1:42179
> 2010-04-09 21:55:36,125 - WARN
> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@606] -
> EndOfStreamException: Unable to read additional data from client sessionid
> 0x0, likely client has closed socket
> 2010-04-09 21:55:36,125 - INFO
> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@1286] - Closed
> socket connection for client /127.0.0.1:42179 (no session established for
> client)
> [phunt@gsbl90850 zookeeper-3.3.0]$ 2010-04-09 21:55:36,126 - ERROR
> [Thread-15:NIOServerCnxn@422] - Unexpected Exception:
> java.nio.channels.CancelledKeyException
> at sun.nio.ch.SelectionKeyImpl.ensureValid(SelectionKeyImpl.java:55)
> at sun.nio.ch.SelectionKeyImpl.interestOps(SelectionKeyImpl.java:59)
> at
> org.apache.zookeeper.server.NIOServerCnxn.sendBuffer(NIOServerCnxn.java:395)
> at
> org.apache.zookeeper.server.NIOServerCnxn$SendBufferWriter.checkFlush(NIOServerCnxn.java:907)
> at
> org.apache.zookeeper.server.NIOServerCnxn$SendBufferWriter.flush(NIOServerCnxn.java:945)
> at java.io.BufferedWriter.flush(BufferedWriter.java:236)
> at java.io.PrintWriter.flush(PrintWriter.java:276)
> at
> org.apache.zookeeper.server.NIOServerCnxn$2.run(NIOServerCnxn.java:1089)
> 2010-04-09 21:55:36,126 - ERROR [Thread-15:NIOServerCnxn$Factory$1@82] -
> Thread Thread[Thread-15,5,main] died
> java.nio.channels.CancelledKeyException
> at sun.nio.ch.SelectionKeyImpl.ensureValid(SelectionKeyImpl.java:55)
> at sun.nio.ch.SelectionKeyImpl.interestOps(SelectionKeyImpl.java:64)
> at
> org.apache.zookeeper.server.NIOServerCnxn$SendBufferWriter.wakeup(NIOServerCnxn.java:927)
> at
> org.apache.zookeeper.server.NIOServerCnxn$SendBufferWriter.checkFlush(NIOServerCnxn.java:909)
> at
> org.apache.zookeeper.server.NIOServerCnxn$SendBufferWriter.flush(NIOServerCnxn.java:945)
> at java.io.BufferedWriter.flush(BufferedWriter.java:236)
> at java.io.PrintWriter.flush(PrintWriter.java:276)
> at
> org.apache.zookeeper.server.NIOServerCnxn$2.run(NIOServerCnxn.java:1089)
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