What is the difference between a process and a thread?

Question

What is the technical difference between a process and a thread?

I get the feeling a word like \'process\' is overused and there are also hardware and software threa

Answer 1

Coming from the embedded world, I would like to add that the concept of processes only exists in "big" processors (desktop CPUs, ARM Cortex A-9) that have MMU (memory management unit) , and operating systems that support using MMUs (such as Linux). With small/old processors and microcontrollers and small RTOS operating system (real time operating system), such as freeRTOS, there is no MMU support and thus no processes but only threads.

Threads can access each others memory, and they are scheduled by OS in an interleaved manner so they appear to run in parallel (or with multi-core they really run in parallel).

Processes, on the other hand, live in their private sandbox of virtual memory, provided and guarded by MMU. This is handy because it enables:

1. keeping buggy process from crashing the entire system.
2. Maintaining security by making other processes data invisible and unreachable. The actual work inside the process is taken care by one or more threads.