[MPICH] Failure of MPI_Recv related to timing - need help

[Glaser, Amnon]

Hello All

I have a problem with MPICH2 implementation that seems to be highly 
sensitive to timing (!)

In case I use many processes, each communicating less, the program works
fine.
 
When I increase the amount of work and communications per worker by 
lowering the number of workers or by turning the clog2 logging on,
I start having frequent failures of the MPI_Recv service.

Am I doing something wrong or its a known problem ?

//------------{ usage sample }-----------
MPI_Status msgStatus ;

MyAnswerClass answer ;

MPI_Recv((void*)&answer,sizeof(MyAnswerClass),MPI_CHAR,MPI_ANY_SOURCE,MP
I_ANY_TAG,MPI_COMM_WORLD,&msgStatus);

if (msgStatus.MPI_ERROR == MPI_SUCCESS)
{
	// Process incoming message according to its TAG
}
else
{
	char errorStr[MPI_MAX_ERROR_STRING];
	int errorStrLen ;
	MPI_Error_string(msgStatus.MPI_ERROR,errorStr,&errorStrLen);
	printf("Rank: %d, Error code (%d) while receiving message:
%s\n",m_myRank,msgStatus.MPI_ERROR,errorStr);
	fflush(stdout);
}
//---------{ end of usage sample }---------


// The resulting error print out
Rank: 1, Error code (-858993460) while receiving message: Undefined
dynamic error code

The value -858993460 is 0xCCCCCCCC - the value of uninitialized memory
location in debug version
In release version the value I get is -1.

// Additional information:
// I link the release version with "mpi.lib cxx.lib" and /MD
// I link the release version with "mpi.lib cxxd.lib" and /MDd

To sum up: the problem appears or goes away just by changing the number
of Processes 
Or by turning on/off the logging without changing anything in the
executable (!)

Any Ideas ?

Thank you for your time
Amnon


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