Re: Weblogic JDBC driver problem with multithread environement



GoJ wrote:

Hi, I encounter a problem with a Java application, during performance
tests with many threads.
With Weblogic 8.1 and a driver JDBC type 4, the DB is SQL Server 2000

An exception occured on a RestultSet.next().
The SQL error message is not explicit :cry:

java.sql.SQLException: [BEA][SQLServer JDBC Driver][SQLServer] weblogic.jdbc.base.BaseExceptions.createException(Unknown Source)
weblogic.jdbc.base.BaseExceptions.getException(Unknown Source)
weblogic.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown..)
weblogic.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown..)
weblogic.jdbc.sqlserver.tds.TDSRPCRequest.processReplyToken(..)
weblogic.jdbc.sqlserver.tds.TDSRPCCursorExecuteRequest.processReplyTok
en()
weblogic.jdbc.sqlserver.tds.TDSRequest.processReply(..)
weblogic.jdbc.sqlserver.tds.TDSRequest.getRow(..)
weblogic.jdbc.sqlserver.tds.TDSRPCCursorExecuteRequest.getRow(..)
weblogic.jdbc.sqlserver.tds.TDSRPCCursorExecuteRequest.fetchNext(..)
weblogic.jdbc.sqlserver.SQLServerImplResultSetServerSideCursor.next(Un
known
Source)
weblogic.jdbc.base.BaseResultSet.next(Unknown Source)
weblogic.jdbc.wrapper.ResultSet_weblogic_jdbc_base_BaseResultSet.next


A various percentage of threads between 50% and 90% gets an error
below, at result1.next()


try{
pstmt1= contexte.getConnection().prepareStatement(SELECT_EQUIPE); pstmt1.setLong(1, ...);
pstmt1.setString(2, ...);
result1 = pstmt1.executeQuery();
...
while (result1.next()){
...
}
result1.close();
fermerPreparedStatement(pstmt1,voi);
} finally {
result1.close();
fermerPreparedStatement(pstmt1,voi);
}

Connections are opened and closed by the framework, we only handle
here the statements and resultset. Other accesses to the DB in a
similar way work fine elsewhere in the application but here it throws
this exception.
The pool is large enough (100 to 150 connections, for 40 threads), it
runs with selectMethod=cursor, row prefetched enable.

Any information about such an error ? I miss good ideas :oops: 

Hi. BEA also has newsgroups that are more tailored to WebLogic JDBC...
You may be suffering from a non-thread-safety issue in your code.
Are you absolutely sure that no two threads are getting the same
connection?
    The code is not how a typical symmetrical call sequence should be.
It should be like:

    Connection c = null; // Make this a *local method* variable!
    try {
        c = myDataSource.getConnection(); // only this thread gets or uses c
                                          // Statement is local to try block
        PreparedStatement pstmt1= c.prepareStatement(SELECT_EQUIPE);
        pstmt1.setLong(1, ...);
        pstmt1.setString(2, ...);
        ResultSet result1 = pstmt1.executeQuery();
        ...
        while (result1.next()) {
        }
        result1.close();
        pstmt1.close();
    }
    finally {
      c.close(); // put back into pool, close in any case, ASAP
    }

Joe Weinstein at BEA



.

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