What is the difference between multi-process and multi-thread?

The main difference between multi-process and multi-thread is: 1. Threads are a subset of processes, and a process may be composed of multiple threads; 2. The data of multi-processes are separated and sharing is complicated, requiring IPC. , but synchronization is simple; 3. Multi-threads share process data, sharing is simple, but synchronization is complex.

What is multi-process?

A process is an execution activity of a program on a computer, that is, a running application, usually called a process. When you run a program, you start a process. Each process has its own independent address space (memory space). Whenever a user starts a process, the operating system will allocate an independent memory space to the process and allow the application to run in this independent memory space.

At the same time, if two or more processes are allowed to be running in the same computer system, this is multi-process, also known as multi-tasking. Modern operating systems are almost all multi-tasking operating systems that can manage the running of multiple processes at the same time.

The benefits of multitasking are obvious. For example, you can surf the Internet while listening to MP3s, and at the same time, you can even print out downloaded documents, and these tasks will not interfere with each other at all.

What is multi-threading?

A thread is a lightweight sub-process, the smallest processing unit; it is a separate execution path. It can be said that: a thread is a subset (part) of a process, and a process may consist of multiple threads.

Threads are independent. If an exception occurs in one thread, it does not affect other threads. It uses shared memory area.

Multi-threading is an execution model that allows multiple threads to exist within the context of a process so that they execute independently but share their process resources.

The difference between multi-process and multi-thread

Dimension	Multiple processes	Multiple threads	Summary
Data sharing , Synchronization	Data is separated, sharing is complicated and requires IPC; synchronization is simple	Multiple threads share process data, sharing is simple; synchronization is complex	Each has its own advantages
Memory, CPU	Occupies a lot of memory, complex switching, low CPU utilization	Occupies little memory, simple switching, high CPU utilization	Thread dominance
Creation, destruction, switching	Creation, destruction, and switching are complicated and slow	Creation, destruction, and switching are simple and fast	Thread dominance
Programming and debugging	Simple programming, simple debugging	Complex programming, complex debugging	Process Dominance
Reliability	Processes will not affect each other	If one thread hangs up, the entire process will hang up	Process Dominance
Distributed	Suitable for multi-core and multi-machine distribution; if one machine is not enough, it is easier to expand to multiple machines	Adapted to multi-core distribution	Thread dominance

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