What is the relation between a thread and a process?

Answer 1

Threads exist within the same process; they can share memory and take less time to perform a "context switch;" they are part of the same program running in parallel processing units. Threads each have their own dedicated memory, and a shared memory area. Processes are entirely partitioned units of executing code. They cannot directly share memory with each other without assistance from the operating system, and are protected from each other by the operating system (in most modern operating systems, that is). They require more time to perform a context switch, as the entire task must be swapped out of the CPU instead of just the thread stack.

Answer 2

A thread is a thread of execution within a process. A process may be composed of one or more threads. Typically you will use the main thread (the entry point of the application) to create additional threads as required. Each thread has its own call stack (so the same function can execute in different threads) but shares the same address space as the process. When threads share the same resources, those resources must be synchronised such that when one thread is writing to a resource, all other threads are blocked from accessing that resource until the resource is unlocked by the writer. Failure to synchronise can result in data races, where a thread that is reading data might end up reading partially overwritten data. Care must also be taken to avoid deadlocks, where a thread attempts to lock a resource that can never be released. This can happen when a thread locks a resource and then attempts to lock that same resource a second time without releasing the first lock (this is particularly problematic in recursive functions). It can also happen when two separate threads attempt to lock multiple resources but do so in a different order.

Multiple threads help applications remain responsive even when the process is busy. For instance, if our application has a GUI, we would normally expect the user to be able to interact with the GUI even if the process is busy with a time-consuming task. To achieve this, our main thread simply monitors the message queue in an infinite loop. When a message to begin a task is encountered, the task can be delegated to a worker thread. Meanwhile, the main thread can continue to process other messages, which may include messages from the worker thread such as informing the main thread of its progress. Although multi-threading is by no means simple, by thinking in terms of independent or coordinated tasks that can execute concurrently, we can (generally) perform those tasks much quicker than we could by running them sequentially, and our application remains responsive.

Answer 3

• Unlike processes, threads are not independent of one another.
• Unlike processes, all threads can access every address in the task .
• Unlike processes, thread are design to assist one other. Note that processes might or might not assist one another because processes may originate from different users.

Answer 4

Every process has at least one thread of execution, the main thread. However, threads can create new threads that operate concurrently with the main thread. Thus a process is a collection of one or more concurrent threads.

Answer 5

Every process allocated its own data memory but all threads shares same memory .

Answer 6

a thread represents a line of execution within a process. processes can be multithreaded, that is, they can have several different lines of execution occurring simultaneously.

Answer 7

Both process and thread are independent sequence of execution

Answer 8

The same address space.