blocks|key|433984|text|如果你有一个包含异步请求的循环，并且你希望每个请求之间有一定的时间间隔，你可以使用下面的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|433985|+++var+startTimeout+=+function(timeout,+i){
++++++++setTimeout(function()+{
++++++++++++myAsyncFunc(i).then(function(data){
++++++++++++++++console.log(data);
++++++++++++})
++++++++},+timeout);
+++}

+++var+myFunc+=+function(){
++++++++timeout+=+0;
++++++++i+=+0;
++++++++while(i+<+10){
++++++++++++//+By+calling+a+function,+the+i-value+is+going+to+be+1..+10+and+not+always+10
++++++++++++startTimeout(timeout,+i);
++++++++++++//+Increase+timeout+by+1+sec+after+each+call
++++++++++++timeout+%2B=+1000;
++++++++++++i%2B%2B;
++++++++}
++++}|code-block|syntax|javascript|433986|此示例在每个请求后等待1秒，然后发送下一个请求。|433987|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

In case you have a loop with an async request in each one and you want a certain time between each request you can use this code:

<pre><code> var startTimeout = function(timeout, i){
 setTimeout(function() {
 myAsyncFunc(i).then(function(data){
 console.log(data);
 })
 }, timeout);
 }

 var myFunc = function(){
 timeout = 0;
 i = 0;
 while(i &lt; 10){
 // By calling a function, the i-value is going to be 1.. 10 and not always 10
 startTimeout(timeout, i);
 // Increase timeout by 1 sec after each call
 timeout += 1000;
 i++;
 }
 }
</code></pre>

This examples waits 1 second after each request before sending the next one.

blocks|key|215951|text|在使用第三方库提供的异步函数或观察值时，例如Cloud+firestore，我已经找到了如下所示的waitFor方法的函数(TypeScript，但您明白了……)当你需要等待某个进程完成，但又不想在回调中嵌入回调，也不想冒着无限循环的风险时，这是很有帮助的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|215952|这种方法有点类似于while+(!condition)休眠循环，但会以异步方式产生，并定期对完成条件执行测试，直到为真或超时。|215953|export+const+sleep+=+(ms:+number)+=>+{
++++return+new+Promise(resolve+=>+setTimeout(resolve,+ms))
}
/**
+*+Wait+until+the+condition+tested+in+a+function+returns+true,+or+until+
+*+a+timeout+is+exceeded.
+*+@param+interval+The+frenequency+with+which+the+boolean+function+contained+in+condition+is+called.
+*+@param+timeout++The+maximum+time+to+allow+for+booleanFunction+to+return+true
+*+@param+booleanFunction:++A+completion+function+to+evaluate+after+each+interval.+waitFor+will+return+true+as+soon+as+the+completion+function+returns+true.+++
+*/
export+const+waitFor+=+async+function+(interval:+number,+timeout:+number,
++++booleanFunction:+Function):+Promise<boolean>+{
++++let+elapsed+=+1;
++++if+(booleanFunction())+return+true;
++++while+(elapsed+<+timeout)+{
++++++++elapsed+%2B=+interval;
++++++++await+sleep(interval);
++++++++if+(booleanFunction())+{
++++++++++++return+true;
++++++++}
++++}
++++return+false;
}|code-block|syntax|javascript|215954|说你在后端有一个长时间运行的进程，你想在承担其他任务之前完成。例如，如果你有一个汇总账户列表的函数，但你想在计算之前从后台刷新账户，你可以这样做：|215955|async+recalcAccountTotals()+:+number+{
+++++this.accountService.refresh();+++//start+the+async+process.
+++++if+(this.accounts.dirty)+{
+++++++++++let+updateResult+=+await+waitFor(100,2000,()=>+{return+!(this.accounts.dirty)})
+++++}
+if(!updateResult)+{+
++++++console.error("Account+refresh+timed+out,+recalc+aborted");
++++++return+NaN;
++++}
+return+...+//calculate+the+account+total.+
}|215956|entityMap^0|1D|7|0|9|I|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

When working with async functions or observables provided by 3rd party libraries, for example Cloud firestore, I've found functions the <code>waitFor</code> method shown below (TypeScript, but you get the idea...) to be helpful when you need to wait on some process to complete, but you don't want to have to embed callbacks within callbacks within callbacks nor risk an infinite loop.

This method is sort of similar to a <code>while (!condition)</code> sleep loop, but
yields asynchronously and performs a test on the completion condition at regular intervals till true or timeout. 

<pre><code>export const sleep = (ms: number) =&gt; {
 return new Promise(resolve =&gt; setTimeout(resolve, ms))
}
/**
 * Wait until the condition tested in a function returns true, or until 
 * a timeout is exceeded.
 * @param interval The frenequency with which the boolean function contained in condition is called.
 * @param timeout The maximum time to allow for booleanFunction to return true
 * @param booleanFunction: A completion function to evaluate after each interval. waitFor will return true as soon as the completion function returns true. 
 */
export const waitFor = async function (interval: number, timeout: number,
 booleanFunction: Function): Promise&lt;boolean&gt; {
 let elapsed = 1;
 if (booleanFunction()) return true;
 while (elapsed &lt; timeout) {
 elapsed += interval;
 await sleep(interval);
 if (booleanFunction()) {
 return true;
 }
 }
 return false;
}
</code></pre>

The say you have a long running process on your backend you want to complete before some other task is undertaken. For example if you have a function that totals a list of accounts, but you want to refresh the accounts from the backend before you calculate, you can do something like this:

<pre><code>async recalcAccountTotals() : number {
 this.accountService.refresh(); //start the async process.
 if (this.accounts.dirty) {
 let updateResult = await waitFor(100,2000,()=&gt; {return !(this.accounts.dirty)})
 }
 if(!updateResult) { 
 console.error("Account refresh timed out, recalc aborted");
 return NaN;
 }
 return ... //calculate the account total. 
}
</code></pre>

As per <a href="http://blog.mixu.net/2011/02/01/understanding-the-node-js-event-loop/">Understanding the node.js event loop</a>, node.js supports a single thread model. That means if I make multiple requests to a node.js server, it won't spawn a new thread for each request but will execute each request one by one. It means if I do the following for the first request in my node.js code, and meanwhile a new request comes in on node, the second request has to wait until the first request completes, including 5 second sleep time. Right?

<pre><code>var sleep = require('sleep');
 sleep.sleep(5)//sleep for 5 seconds
</code></pre>

Is there a way that node.js can spawn a new thread for each request so that the second request does not have to wait for the first request to complete, or can I call sleep on specific thread only?

How to sleep the thread in node.js without affecting other threads?

TypeScript

服务器

根据，node.js支持单线程模型。这意味着如果我向node.js服务器发出多个请求，它不会为每个请求产生新的线程，而是逐个执行每个请求。这意味着如果我在node.js代码中对第一个请求执行了以下操作，同时节点上出现了一个新请求，则第二个请求必须等待第一个请求完成，包括5秒睡眠时间。对吗？var sleep = req...

问如何在不影响其他线程的情况下休眠node.js中的线程？
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