Load Balancing a java application running in a cluster

Question

I have multiple vms running all of the modules in the project. Each request created by the user has to be processed by all modules, but needs to be done only once. So if VM1 picks up a request then module1 can process the request partially, next VM1 or VM2 or any other VM in cluster can pick up and process for module2. And so on.

Since each VM is of limited capacity i would like to use a load balancer for allocating work among individual VM's.

Are there load balancers(open source for java) available which can solve this or do i need to implement it using several load balancing algos(round robin,weighted etc) for solving my requirement?

Edit 1:

Each module is a java class which is independent in itself but needs previous modules to be done before its started.Each Vm is listening to a message bus. As and when a message appears in the bus any of the vm can pick up this and start working on it.

Answer 1

You can try HAProxy (TCP/HTTP loadbalancer ) which is open source, feature rich and quite widely used. Apart from good documentation you can find lots of information available.

Answer 2

Depending on the exact semantics of the problem you're trying to parallelize, you might get good results by chunking your problem into "work packets" of some size and keeping them in a central queue. Then, just have each VM poll a packet from said queue as soon as it finished the previous packet. This is called self-scheduling.