FreeTDS Development Group

["ou liu" <ou AT qbt.com>]

Hi,
        I got problems when I was trying to do SQLExecute and the connection
to server is down. The error log looks like:
        [FreeTDS][SQL Server]Write to SQL server failed. 08S01
        
        I am trying to reproduce problem by disconnecting the cable on the
SQL server, but I can only reproduce following error
        [FreeTDS][SQL Server]Read from SQL server failed. 08S01

        My code is somewhat like this:
----------------------------------------------------------------------------
        Conn = SQLAllocHandle(...); // Allocate connection handle, at this
time the connection is ok
        
        Stmt = SQLAllocHandle(...); // Allocate statement handle, at this
time the connection is ok

        // Use the stmt to do some querying, also ok.

        // Now I disconnect the cable

/* The latest FreeTDS asks us to totally close a statement handle before we
fetch another resultset */
#ifdef USE_FREETDS
        if (m_hstmt != NULL)
        {
                SQLFreeStmt(Stmt, SQL_CLOSE);
                SQLFreeStmt(Stmt, SQL_UNBIND);
                SQLFreeStmt(Stmt, SQL_RESET_PARAMS);
        }
#endif

        /* Maybe the cursor is not closed yet, anyhow we close it */
        iRet = SQLCloseCursor(Stmt);    

        /* Set the CommandTimeOut property */
        iRet = SQLSetStmtAttr (Stmt, SQL_ATTR_QUERY_TIMEOUT, ...);
                        
        /* Bind all Paramters */
        // code removed ...

        SQLPrepare (Stmt, (UCHAR *) SQLText, SQL_NTS);
        SQLExecute (Stmt);
----------------------------------------------------------------------------

        Now no matter what error I got, if I tried to close the statement
handle by SQLCloseHandle(Stmt) I always got a 
        [FreeTDS][SQL Server]Attempt to initiate a new SQL Server operation
with results pending. 07005

        My questions are as follows:
        1. Why I can't close the statement handle
        2. How can I reproduce the " Write to SQL server failed". (This
error always happens when nobody is in the room) One thing may help is that
the "Write to SQL server failed" error appears immediately after I call the
SQLExecute, but if I disconnected the cable it will took 8 minutes for the
"Read from SQL server failed". (The poll() call on Solaris should fail after
4 minutes 30 seconds, am I wrong?)
        3. The problem may lead to freeze of our application. The code above
is shared among 3 threads each having their own data. From the log we found
that when the connection keeps up and down, the application sometimes will
totally freeze. The thing I can't understand is that we have more than 15
threads in our application and most of them have nothing to do with database
thread (even not sharing a single variable) and they all seemed freezed. But
it's very difficult to reproduce. I found in the old email somebody mention
something similar on May/22/2004:
------------------------------------------------
Hi,
 
  I am writing a program to copy data from 10 MSSQL server  to one central
DB2 server using unixODBC 2.2.8, FreeTDS 0.62.1 and DB2 8.1.5 ODBC under
RHEL AS 3.0
 
  The program is multi threaded and each thread connect to certain MSSQL
server, it works fine until one of the sever is unreachable ( i cannot ping
it from Linux command line) at this point i get an error from FreeTDS :
   server 192.122.122.12   connect time out
 
  at this point the program freeze and all threads freeze totally
 
  any ideas ?
 
 
 
  Hany Heggy,
 
  IBM Certified System Support, AIX 4.3
  Senior System Engineer 
  GDMC
  Media City Public Free Zone
  6th of October City, Egypt
  Mobile: +20-101717563
------------------------------------------------

        Is there anybody having the same problem of the freezing?

        I am using the latest FreeTDS and SQL Server 2K, my program is
running on Solaris 9/SPARC

Regards
Ou