Hi, Thanks for all your reply. I attached the code in the email. I downloaded : Rhapsodia.Schedulerfrom http://rhascheduler.sourceforge.net/because I need to do application program level task scheduling. In file "TaskPackSystem.hpp", I designed a task class "TaskPackage" to carry my defined task. Other classes in the file are not used. My main program is mpi_message_transfer.cpp, which can transfer tasks from master to workers and then collects results from them. Right now, I am testing 3 tasks (TOTALTASKNUM =3) and 2 workers (nodes). I use 3 nodes totally, another node is the master. node 0 : is master. node 1 : worker 1 assigned with task 1 and 3. node 2 : worker 2 assigned with task 2. Each task has a distinct tag, which is assigned by master before it is sent out to a worker. After receiving a task and doing its local work on the task, the worker uses the same tag ID to send it to master. The master use non-blocking world.recv(resultSourceRank, tagID, resultTaskPackage) to get the result task. You may need to download the Rhapsodia.Scheduler to get their header files. I attached the 4 files in the email. mpi_message_transfer.cppTaskPackSystem.hppBasicScheduler.hppSimpleScheduler.hpp Any help is appreciated. thanks Jack July 5 2010 From: kbelco@sandia.gov To: boost-users@lists.boost.org Date: Mon, 5 Jul 2010 21:21:35 -0600 Subject: Re: [Boost-users] Boost MPI, error to get message Hi Jack On Jul 5, 2010, at 7:14 PM, Jack Bryan wrote:Is it possible for my program [to] work in native MPI, but not in Boost MPI ? Yes, this would imply a bug in Boost.MPI. But Boost.MPI is pretty well tested and is used by a number of people. That's why I suspect the problem may be in your framework code. Eliminating Boost.MPI from the equation should make it easier for you to uncover the source of the problem. -- Noel _________________________________________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4