Relationship and differences between processes and threads

relationship of process and thread:
(1) A thread can belong to only one process, while a process may have multiple threads, but at least one thread.
(2) A resource is allocated to a process, and all the threads of the same process share all the resources of that process.
(3) The processor is assigned to a thread, that is, a thread that is actually running on the processing machine.
(4) Threads need to be synchronized during execution. Synchronization is achieved between threads of different processes using the means of message communication.
A thread is an execution unit within a process and a scheduler within a process.
the difference between a thread and a process:
(1) Dispatch: The thread acts as the basic unit of dispatch and allocation, and the process as the basic unit of resources
(2) Concurrency: Not only can concurrent execution between processes, but also concurrent execution between multiple threads of the same process
(3) Owning a resource: a process is an independent unit that owns resources, and threads do not own system resources, but they can access resources that belong to the process.
(4) Overhead: When you create or revoke a process, the overhead of the system is significantly greater than the cost of creating or revoking a thread, because the system allocates and reclaims resources for it. However, the process has a separate address space, and after a process crashes, it does not affect other processes in protected mode, and the thread is just a different execution path in a process. Thread has its own stack and local variables, but there is no separate address space between the threads, a thread dead is equal to the entire process dead, so the multi-process program is more robust than multithreaded programs, but in the process of switching, the cost of large resources, the efficiency is worse

Relationship and differences between processes and threads