Thread vs Process

Thread vs Process

What is a Thread, really?

  • Short answer:

    • Thread is a subset of a process
  • Longer answer:

    • Thread is an independent set of values for CPU registers
  • Detailed answer:

    • A thread is an execution context for CPU, which is all the information CPU needs to execute instructions. Essentially:

More about thread

Thread components:

  • Program counter: keeps track of which instruc­tion to execute next
  • Stack: which contains the execution history
  • Registers: which hold its current working variables


A single thread could be displaying the current tab you’re in, and a different thread could be another tab.

What is a Process, really?

  • Short answer:

    • Process is a running program
  • Long answer:

    • The process model is based on two independent concepts: resource grouping and execution (thread)

More about process

Process components:

  • stack: stores functional calls, local variables
  • heap: memory that is dynamically allocated to a process during its execution
  • text/code: code instructions
  • data: static variables


When you double click on the Google Chrome icon on your computer, you start a process which will run the Google Chrome program

Thread vs Process

Essentially: Processes are used to group resources together; threads are the entities scheduled for execution on the CPU.

Comparsion Table

Process is a running programThread is a subset of a process
Process is heavyweightThread is lightweight
The process is independentThreads share memory

Resource Sharing Difference

  • Processes have separate address spaces (indepedent)

  • For multiple threads in the same process

    • Threads share same address space and code, data, heap segments
    • Threads DO NOT SHARE STACK