[kiran2710]

Describe the difference between a Thread and a Process?

[navyseals]

A process is a collection of virtual memory space, code, data, and system resources. A thread is code that is to be serially executed within a process. A processor executes threads, not processes, so each application has at least one process, and a process always has at least one thread of execution, known as the primary thread. A process can have multiple threads in addition to the primary thread
Thread – is stream of executable code within process. They are light weight process.
All thread with in a process share process instruction,code & data segment,open file descriptor,signal handler,userID and GroupID. Thread has its own set of register including program counter,stack pointer
The major difference between threads and processes is
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).