| Thread |
Process |
| An executing instance of a program is called a process. |
A thread is a subset of the process. |
| Thread shares the address space of process that they are belonging to. |
Processes have their own address space. |
| Threads have direct access to the data segment of its process. |
Processes have their own copy of data segment of a parent process. |
| Threads can directly communicate with other threads of its process. |
The processes must use interprocess commumnication (IPC) to communicate with other process. |
| Threads have less overhead with context switching. |
Processes have considerable overhead. |
| New threads can be easily created. |
New process requires duplications of a parent process. |
| Threads can exercise a considerable control over threads of a same process. |
Process can only exercise control over its child process. |
| Changes to the main thread may affect the behaviour of other threads of a process. |
Changes to the process does not affect the child process. |
| Threads (of the same process) run in a shared memory space. |
Processes run in separate memory spaces. |
| Every thread is not a process. It is a part(entity) of a process. |
Every process is a thread (primary thread). |
| Threads are light weight processes. Threads are bundled inside the process. |
Process is a heavy weight process. |
| Threads are created using clone() method. |
Process are created using fork() method. |
