Unity update process_ Principle of unity synergy

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Unity The principle of CO process

Release time ：2019-06-13 18:45,

A coroutine is not multithreaded , The coroutine is still in the main thread ( notes ： stay Unity The Central African main thread is not accessible Unity Resources )

1、 Threads 、 The difference between process and coroutine

The process has its own independent heap and stack , Neither heap nor stack is shared , Processes are scheduled by the operating system

Threads have their own independent stacks and shared heaps , Shared heap does not share stack , Threads also have operating system scheduling ( Standard threads are like this )

Coroutines share heaps and not stacks like threads , The programmer displays the schedule in the code of the coroutine

An application generally corresponds to a process , A process usually has a main thread , There are also several worker threads , Threads are parallel , You can start a coroutine in a thread , Let the program run at a specific time .

The difference between a coroutine and a thread is ： The process avoids meaningless scheduling , This can improve performance , But it is also so , Programmers have to take responsibility for scheduling themselves , meanwhile , Coroutines also lose the standard thread usage CPU The ability of .

2、Unity The principle of intermediate process execution

Put one on first unity Frame operation diagram of the main line ：

stay Unity Runtime , Calling a coroutine is just starting a IEnumerator( iterator ), The process begins to run , In carrying out the yield

return There was no difference from other normal procedures , But when it comes to yield

return And I'll be back immediately , And suspend the function temporarily . In the next frame FixedUpdate perhaps Update After judgment yield return

Whether the following conditions are satisfied , If satisfied, execute downward .

according to unity We know the main frame diagram , Collaborative programs are mainly in update() After method ,lateUpdate() Call before method .

Unity The impact of the life cycle on the process ：

By setting MonoBehaviour The script enabled There's no impact on Xiecheng , But if gameObject.SetActive(false)

Then the started coroutine stops completely , Even in Inspector hold gameObject

Activation is still not continuing . In other words, although Xiecheng is MonoBehvaviour Starting up (StartCoroutine) But the position of coprogram function is completely related to MonoBehaviour It's a hierarchical , Not subject to MonoBehaviour The state of influence , But follow MonoBehaviour Scripts are just as popular as gameObject

control , It should also be with MonoBehaviour Script like every frame “ polling ” yield Whether the conditions of .

notes ：WaitForSends() suffer Time.timeScale influence , When Time.timeScale = 0f when ,yieldreturn new

WaitForSecond(X) Will not be satisfied .

3、 The main applications of coprocessing are

The coroutine can't just do some simple delays , If you simply pause for a few seconds and then execute, there is no need to start a thread .

The real function of coprocessing is to do some time-consuming things step by step , For example, loading resources in the game

using System.Collections; using System.Collections.Generic; using

System.Threading; using UnityEngine; public class Test : MonoBehaviour {

private int num = 0; void Start() { StartCoroutine(Test1()); } IEnumerator

Test1() { while (num < 30) { num++; Debug.Log(num); yield return null;

Debug.Log(“————-” + num); } } void Update() { Debug.Log(“update” +

num); } void LateUpdate() { Debug.Log(“lateUpdate!” + num); } }

The above example is very simple: loading 30 Objects , If it is loaded at one time, it will get stuck , Influence the game experience . This is how we can use the synergy , The co process is every frame LateUpdate Before execution yield

return Previous code ,LateUpdate After performing yield return

Later code ( You can see from the above small example ). In this way, we can load one per frame until the loading is completed , There will be no Caton .

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