Distributed Programming is Hard!

• 1000's of processors require 1000's of programs.

• Need to keep processors busy.

• Processors must be synchronized so they do not interfere with each other.

• Need to avoid bottlenecks (most of the processors waiting for service from one processor).

• Some machines may become:
  • slow

  • dead

  • evil
  and they may change into these states while your application is running.

• If a machine does not have the data it needs, it must get the data via the network.

• Many machines share one (slow) network.

• Parts of the network can fail too.