I am running a java class that queries mysql via JDBC, the database is
also servicing a GUI via tomcat (connection pool)

All of a sudden the java application crashes and below is the log file
output that I get

So - I'm left wondering if this is a mysql error......or tomcat
messing with connection pool ..... or JDBC error.....???

I cannot find any good info on the web for the error, so any feedback
appreciated



------------------------------------------------------------------------------------------------------------------------------------------
SelectStr: show tables
Error while executing SQL transaction: No operations allowed after
connection closed.Connection was implicitly closed due to underlying
exception/error:


** BEGIN NESTED EXCEPTION **

com.mysql.jdbc.exceptions.jdbc4.CommunicationsExce ption
MESSAGE: Communications link failure

Last packet sent to the server was 1 ms ago.

STACKTRACE:

com.mysql.jdbc.exceptions.jdbc4.CommunicationsExce ption:
Communications link failure

Last packet sent to the server was 1 ms ago.
at sun.reflect.GeneratedConstructorAccessor13.newInst ance(Unknown
Source)
at
sun.reflect.DelegatingConstructorAccessorImpl.newI nstance(DelegatingConstructorAccessorImpl.java:
27)
at java.lang.reflect.Constructor.newInstance(Construc tor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:40 6)
at
com.mysql.jdbc.SQLError.createCommunicationsExcept ion(SQLError.java:
1074)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO. java:2873)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO. java:2763)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.ja va:3299)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:18 37)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java :1961)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionIm pl.java:2537)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionIm pl.java:2466)
at com.mysql.jdbc.StatementImpl.executeQuery(Statemen tImpl.java:
1383)
at com.sun.electron.utils.DBConnection.doSelect(DBCon nection.java:
402)
at com.sun.electron.utils.DBConnection.doSelect(DBCon nection.java:
382)
at com.sun.electron.utils.DBConnection.doSelect(DBCon nection.java:
370)
at
com.sun.electron.utils.DBConnection.isAliveAtDBLev el(DBConnection.java:
196)
at com.sun.electron.utils.DBConnection.isAlive(DBConn ection.java:
185)
at
com.sun.electron.utils.DBConnection.getConnectionS tate(DBConnection.java:
207)
at
com.sun.electron.utils.DBConnection.printStates(DB Connection.java:224)
at com.sun.electron.utils.RweServer.main(RweServer.ja va:101)
Caused by: java.io.EOFException: Can not read response from server.
Expected to read 4 bytes, read 0 bytes before connection was
unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2332 )
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO. java:2774)
... 15 more


** END NESTED EXCEPTION **

Il 27/04/2011 8.39, terry433iid (AT) yahoo (DOT) com ha scritto:
[...]
I rarely get the same error using a standalone application and the
Apache dbcp connection pool. A definitive answer seems to be not
existing (except '42'). The common problem should be a failure link to
the database server (network errors).

regards,
M.

On Tue, 26 Apr 2011 23:39:03 -0700 (PDT), terry433iid (AT) yahoo (DOT) com wrote:
The database connection went away unexpectedly. Probably because the
network means that the communications link was using got closed
unexpectedly. If the database is still running and other connections are
working, it's not the database doing it.

--
Christian Biblical literalists are trusting themselves to an archaic
English translation of a Latin translation of (help me here) Greek?
Aramaic? source. I wouldn't even trust a VCR manual to make it through
that intact. - Dr. Dee