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This article mainly shows you "what are the differences between processes and threads in Java development", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "what are the differences between processes and threads in Java development" this article.

1. What are the definitions of process and thread respectively

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.

two。 The relationship between processes and threads

One thread can create and undo another thread; multiple programs in the same process can be executed concurrently. Compared with a process, a thread is a concept closer to the executor, which can share data with other threads in the same process, but has its own stack space and independent execution sequence.

3. The difference between processes and threads

The main difference between processes and threads is that they are different ways of managing operating system resources. A process has an independent address space. After a process crashes, it will not affect other processes in protected mode, and threads are just different execution paths in a process. A thread has its own stack and local variables, but there is no separate address space between threads. The death of a thread equals the death of the whole process, and the multi-process program is more robust than the multi-threaded program, but when the process is switched, it consumes more resources and is less efficient.

However, for some concurrent operations that require simultaneous and shared variables, you can only use threads, not processes:

An in short, a program has at least one process and a process has at least one thread.

The partition scale of b thread is smaller than that of process, which makes multithreaded programs have high concurrency.

C in addition, the process has an independent memory unit during execution, and multiple threads share memory, which greatly improves the efficiency of the program.

D threads are different from processes in the process of execution. Each independent thread has an entrance to the program, a sequential execution sequence, and an exit to the program. However, threads cannot execute independently and must be stored in the application, and multiple thread execution control must be provided by the application sequence.

E from a logical point of view, the meaning of multithreading is that there are multiple execution parts in an application that can be executed at the same time. However, the operating system does not regard multiple threads as multiple independent applications to achieve process scheduling and management and resource allocation. This is the important difference between processes and threads.

4. Advantages and disadvantages of processes and threads

Threads and processes have their own advantages and disadvantages: thread execution overhead is small, but it is disadvantageous to the management and protection of resources, while the process is just the opposite. At the same time, threads are suitable for running on SMP machines, while processes can be migrated across machines.

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