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What is the difference between a process and a thread? I believe many inexperienced people are at a loss about it. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

The definition of both

A process is a running activity of a program with a certain independent function on a certain data set, and a process is an independent unit of resource allocation and scheduling in the system. A thread is an entity of a process and the basic unit of CPU scheduling and dispatching. It is a smaller basic unit that can run independently than a process. The thread itself basically does not own system resources, only a few resources that are essential to running (such as program counters, a set of registers and stacks), but it can share all the resources owned by the process with other threads belonging to the same process. The difference between a process and a thread is that the process is the smallest unit of resource allocation, and the thread is the smallest unit of program execution; the process has its own independent address space, each time a process is started, the system allocates the address space for it, and establishes a data table to maintain the code segment, stack segment and data segment. The thread does not have an independent address space, and it uses the same address space to share data; it costs less to switch a thread than to switch processes in CPU. Creating a thread is less expensive than a process; threads consume much less resources than a process. Communication between threads is more convenient. Under the same process, threads share global variables, static variables and other data. Communication between processes needs to be carried out by means of communication (IPC). (but it is difficult for multithreaded programs to handle synchronization and mutual exclusion) multiprocess programs are safer and more vital, and the death of one process will not affect another (because of having a separate address space), and multithreaded programs are more difficult to maintain. if one thread dies, the whole process dies (because of the shared address space). The process has high requirements for resource protection, high overhead, relatively low efficiency, and low requirements for thread resource protection, but low overhead, high efficiency, and frequent switching. To enhance understanding, make a simple analogy: process = train, thread = car thread moving under the process (a simple car cannot run) A process can contain multiple threads (a train can have multiple carriages) data between different processes is difficult to share (it is difficult for passengers on one train to switch to another train For example, station transfer) it is easy to share data between different threads under the same process (it is easy to switch from car A to car B) processes consume more computer resources than threads (using multiple trains consume more resources than multiple carriages) processes do not interact with each other, one thread will cause the whole process to die (one train will not affect another train, but if a train catches fire in the middle of a train The memory address used by the process can be locked, that is, when one thread uses some shared memory, other threads must wait for it to finish before using this memory. (for example, the bathroom on the train)-the memory address used by the "mutex" process can limit the amount of memory used (for example, the restaurant on the train, the maximum number of people allowed to enter, if it is full, you need to wait at the door, wait for someone to come out)-"semaphore"

After reading the above, have you mastered the difference between a process and a thread? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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