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Go language how to use mutex, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain for you in detail, people with this need can come to learn, I hope you can gain something.

1. Basic concept

Critical section (Critical Section): when programs are running concurrently, multiple Go protocols should not simultaneously access code that modifies shared resources, which is called critical sections.

Race condition: it is designed to describe that the output of a system or process depends on the sequence or timing of uncontrolled events. For example, if two processes in a computer try to modify the contents of a shared memory at the same time, in the absence of concurrency control, the final result depends on the execution order and timing of the two processes. And if there is a concurrent access conflict, the final result is incorrect.

Lock: a synchronization mechanism used to forcibly restrict access to resources when performing concurrency, that is, to ensure the satisfaction of mutex requirements in concurrency control. The general lock is the recommended lock (advisory lock). Each thread needs to obtain the lock information before accessing the corresponding resource, and then decide whether it can be accessed according to the information. If the corresponding information is accessed, the state of the lock will be changed to locked, so other threads will not access the resource at this time. When the resource is finished, the state of the lock will be restored and access by other threads will be allowed.

2.mutex introduction

After understanding the basic concepts above, let's take a look at mutex in the Go language.

Mutex is used to provide a locking mechanism to ensure that only one co-program runs in the critical area at a certain time to prevent race conditions.

Mutexs is a data structure in Go's sync package that defines two methods: Lock and Unlock. All code between Lock and Unlock can be executed by only one Go co-program, so race conditions can be avoided.

1) example of not using mutex:

Output:

Result analysis: we executed the program for 5 times and found that the output results were not consistent. The reason is that these 100 coprocesses have a race relationship, so that the result of the calculation is not 100, but becomes an uncertain value.

2) example of using mutex: (we use mutex's locking mechanism to solve this problem)

Output:

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