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Posted to dev@zookeeper.apache.org by "Mahadev konar (JIRA)" <ji...@apache.org> on 2010/04/21 00:49:50 UTC
[jira] Updated: (ZOOKEEPER-737) some 4 letter words may fail with
netcat (nc)
[ https://issues.apache.org/jira/browse/ZOOKEEPER-737?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Mahadev konar updated ZOOKEEPER-737:
------------------------------------
Attachment: ZOOKEEPER-737.patch
this patch fixes the issue.
- it removes the selection key from the selector via calling selectionkey.cancel()
- sends the output of the stat command via the socket and does not use the selector for sending it
- closes the socket appropriately after the server is done sending the response to the client
> 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
> Priority: Blocker
> Fix For: 3.3.1, 3.4.0
>
> Attachments: 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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