Processes

• Inter-process communication in Linux is costly because it requires context switching from user to kernel space and back
• Threads in the same process communicate through shared memory
  • Implemented by running threads in kernel-space lightweight processes with shared resources

Multi-threaded servers

• Often follows a dispatcher/worker pattern

Virtualization

• e.g. running in a VM like the Java Runtime Environment or a virtual machine monitor (VMM)
• VMM benefits:
  • live migration allows load balancing and proactive maintenance
  • VM replication improves availability and fault tolerance

Server clusters

Typically in three tiers:

1. Logic switch
2. Application/compute servers
3. Distribute file/database systems