Error while using threads in proc program

Question

Hi,
I am getting the error fetched column value NULL (-1405) in proc program while using the threads.
The execution of the program is as follows.
Tot_Threads = 5 (Total threads, totally 5 records with value instance names)
No_Of_threads = 1 (No Of threads executed at the same time)
Example :
INSTANCE_NAME – Link1, link2, link3, link4, link5 (All different Databases)
NO_OF_THREADS - 5
Threading Logic:
Based on the maintanence NO_OF_THREADS, the program will process.
     If (NO_OF_THREADS == 0)
          Process_Sequence
     else
          if NO_OF_THREADS == TOT_THREADS
               Process_Type1
          else
               Process_Type2
In a loop for all different instances,
New context area will be created and allocated.
     New oracle session will be created.
     New structure will be created and all global parameters are assigned to that structure.
     For each instance, a new thread will be created (thr_create) and all the threads will call
     the same(MainProcess) function which takes the structure as parameter.
     At the end of every session, the corresponding oracle session will logged out.
Process_Type1 logic :
     /* For Loop for all threads in a loop */
     for(Cnt=0;Cnt < Tot_Threads;Cnt++)
          /* Allocating new contect for every different thread */
          EXEC SQL CONTEXT ALLOCATE :ctx[Cnt];
          /* Connected to new oracle session */
          logon(ctx[Cnt],ConnStr);          
/* Assigning all the global parameters to the structure and then passing it to InsertBatching function */
          DataSet[Cnt].THINDEX=Cnt;
          DataSet[Cnt].sDebug=DebugMode;
          strcpy(DataSet[Cnt].THNAME,(char *)InsNameArr[Cnt].arr);
          DataSet[Cnt].ctx=ctx[Cnt];
          /* creating new threads for time in a loop */
RetVal = thr_create(NULL,0,InsertBatching,&DataSet[Cnt],THR_BOUND,&threads[Cnt]);
          sprintf(LocalStr1,"\nCreated thread %d", Cnt);
          DebugMessage(mptr,LocalStr1,DebugMode);
     for(Cnt=0;Cnt <Tot_Threads;Cnt++)
          /* Waiting for threads to complete */
          if (thr_join(threads[Cnt],NULL,NULL))
               printf("\nError in thread Finish \n");
               exit(-1);
          /* Logout from the specific oracle session */     
          logoff(ctx[Cnt]);
          /* Free the context area after usage */
          EXEC SQL CONTEXT FREE :ctx[Cnt];     
used functions:
          thr_create with thr_suspend option
          thr_join to wait for the thread to complete
Process_Type2 logic :
     Here the idea is , if the load is heavy , then we can change the maintanence of NO_OF_THREADS (Ex - 2), so that only two threads will be executed in the same time , others should wait for      the same to complete ,once the first two threads completed and the next two should be started and then in the same manner it will do for all the threads.
The parameters passing and the structure passing are same as above.
Here all threads will be created in suspended mode, and then only No_Of_threads(2) will
be started, others will be in suspended mode, once the first two is completed then the
other two thread will be started and in the same manner other threads.
     used functions:
          thr_create with thr_suspend option
          thr_continue to start the suspended thread
          thr_join to wait for the thread to complete
Process_Sequence logic :
Here the idea is , to run the program for all the instances , without creating the threads.Hence in the for loop , one by one instance will be taken and call the same function to Process. This will call the same function repeated for each different value. The parameters passing and the structure passing are same as above.
     The InsertBatching function will prepare the cursor and pick all records for batching and then , it will call other individual functions for processing. For all the functions the structure variable will be passed as parameter which holds all the neccessary values.
Here in all the sub functions , we have used
     EXEC SQL CONTEXT USE :Var;
     Var is corresponding context allocated for that thread, which we assume that the corresponding context is used in all sub functions.
     EXEC SQL INCLUDE SQLCA;
This statement we have given in InsertBatching Function not in all sub functiosn
Example for the Sub functions used in the program :-
/* File pointer fptr and dptr are general file pointers , to write the debub messages, DataStruct will hold all global parameters and also context area .
int Insert(FILE fptr,FILE dptr,DataStruct d1)
EXEC SQL BEGIN DECLARE SECTION;
     VARCHAR InsertStmt[5000];
EXEC SQL END DECLARE SECTION;
char LocalStr[2000];
EXEC SQL CONTEXT USE :d1.ctx;
InsertStmt will hold insert statement      
EXEC SQL EXECUTE IMMEDIATE :InsertStmt;
if (ERROR)
     sprintf(LocalStr,"\nError in Inserting Table - %s",d1.THNAME);
     DebugMessage(dptr,LocalStr,d1.sDebug);
     sprintf(LocalStr,"\n %d - %s - %s",sqlca.sqlcode,ERROR_MESG,d1.THNAME);
     DebugMessage(dptr,LocalStr,d1.sDebug);
     return 1;
return 0;
I get this error occationally and not always. While preparing the sql statement also i am getting this error.
The code contains calls to some stored procedures also.
Thanks in advance

Answer 1

in every select nvl is handled and this error is occuring while preparing statements also