process vs thread

A process is a collection of threads that share the same virtual memory. A process has at least one thread of execution, and a thread always run in a process context.
Thread is used to allocate and distribute the CPU work scheduling, many programs a re assigned to different threads and they are most of the time independent of each other.





The major difference between threads and processes

1.Threads(Light weight Processes) share the address space of the process that created it; processes have their own address.

2.Threads have direct access to the data segment of its process; processes have their own copy of the data segment of the parent process.

3.Threads can directly communicate with other threads of its process; processes must use interprocess communication to communicate with sibling processes.

4.Threads have almost no overhead; processes have considerable overhead.

5.New threads are easily created; new processes require duplication of the parent process.

6.Threads can exercise considerable control over threads of the same process; processes can only exercise control over child processes.

7.Changes to the main thread (cancellation, priority change, etc.) may affect the behavior of the other threads of the process; changes to the parent process does not affect child processes.If we consider running a word processing program to be a process, then the auto-save and spell check features that occur in the background are different threads of that process which are all operating on the same data set (your document).