Hi, 

Thanks for all your reply. 

I attached the code in the email. 

I downloaded : Rhapsodia.Scheduler

from 

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.cpp

TaskPackSystem.hpp

BasicScheduler.hpp

SimpleScheduler.hpp