Operating Systemseasy

Processes vs threads — what’s the difference and when does it matter?

Answer

A process has its own address space and resources; threads share the same address space within a process. It matters for isolation, memory overhead, and how you manage shared state and concurrency.

Advanced answer

Deep dive

The choice impacts isolation, performance, and failure modes:

Processes isolate memory; crashes don’t take siblings down.
Threads are cheaper to create and context-switch, but share memory.
IPC between processes is costlier than in-process synchronization.
Security boundaries are easier with processes.

Examples

Web server model:

Many processes: safer isolation, higher memory
Many threads: less memory, more synchronization risk

Common pitfalls

Assuming threads are always faster than processes.
Sharing mutable state without proper synchronization.
Using threads to get isolation (they don’t provide it).

Interview follow-ups

When would you choose multi-process over multi-thread?
How do you avoid shared-state bugs in threads?
How does the OS schedule threads vs processes?