Process Communication: Signals, Pipes, Sockets, Files

• Since process is virtualized, it’s not convenient to communicate

Shared Memory Between Processes

• shmget Allocate shared memory region
• shmat Map shared memory to local address
• mmap Create shared memory regions

Kernel Level Threads: Sharing the same address space, with different execution state

• Same code, static data, heap. Different stack for each thread
• Concurrency is cheaper (fine-grained creation still involve a lot overhead)

User Level Threads: Scheduled by a user process, invisible to OS