Shulou(Shulou.com)06/03 Report--

What is the difference among threads, processes, and programs? I believe that most people do not understand, in order to let you better understand, the editor summed up the following content, do not say much, let's look down together.

First, the concept of program, process and thread:

1. A program is a set of instructions that instruct a computer or other information processing device to perform actions or make judgments, usually written in a programming language and running on a target computer architecture.

two。 A process is a running activity of a software program in a computer on a certain data set, the basic unit of resource allocation and scheduling of the system, and the basis of the structure of the operating system.

3. A thread is an entity in a process and a basic unit that is independently scheduled and dispatched by the system. The thread does not own operating system resources, but the thread can share all the resources owned by the process with other threads belonging to the same process.

4. The process is the entity of the program, and the thread is the entity of the process. The process is the container of the thread.

Second, the differences among programs, processes and threads are as follows:

1. Program: the program cannot be executed alone, it is static, and can only be executed after the program is loaded into memory and the system allocates resources for it.

two。 Process: the dynamic execution of a program to a dataset, in which a process contains one or more threads, a thread can only be owned by one process at the same time, and the process is the basic unit for allocating resources. The process has independent memory units, and multiple threads share memory, thus improving the efficiency of the application.

3. Thread: the thread is the basic scheduling unit within the process, the division scale of the thread is smaller than the process, the concurrency is higher, the thread itself does not own the system resources, but the thread can share all the resources owned by the process with other threads. Each independent thread has an entrance to the program, a sequential execution sequence, and an exit to the program.

3. The differences between multi-process and multi-thread are as follows:

1. Multi-process: each process is independent of each other and does not affect the stability of the main program, and the collapse of one child process has no effect on other processes. By increasing CPU, the performance of the software can be expanded, the influence of thread locking / unlocking can be reduced, and the performance can be greatly improved. The disadvantage is that multi-process logic control is complex, need to interact with the main program, need to cross process boundaries, context switching between processes is more expensive than context switching between threads.

two。 Multithreading: no need to cross-process, program logic and control is simple, all threads share the memory and variables of the process, and so on. The disadvantage is that each thread shares the address space with the main program, the synchronization and locking control between threads is more troublesome, and the collapse of a thread will affect the stability of the whole process or program.

After reading the above, do you have a general understanding of the difference among threads, processes and programs? If you want to know more about the content of the article, welcome to follow the industry information channel, thank you for reading!

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