javascript setTimeout 有什么限制吗？
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Is there any limit to setTimeout?
提问by Mahn
Specifically talking about (server side) V8, and assuming I'm not concerned about accuracy because I can detect and compensate for it, could I literallyset up thousands of relatively simple timeouts several seconds apart from each other using setTimeout without facing any other limit other than RAM? Is there any catch I should be aware of if I were to use a system where there may be thousands of scheduled timeouts at any given time?
具体讲（服务器端）V8，并假设我不关心的准确性，因为我可以检测并对其进行补偿，可我从字面上设立上千个相对简单的超时几秒钟彼此分开使用的setTimeout没有遇到任何其他限制除了内存？如果我要使用在任何给定时间可能有数千个预定超时的系统，我应该注意什么？
For the record I've read John's Resig excellent article on How Javascript Timers workso no need to point out anything that's already covered there :) I'm aware node.js is single threaded, timers can block other timers if they take too long, etc.
作为记录，我已经阅读了 John's Resig 关于Javascript 计时器如何工作的优秀文章，因此无需指出那里已经涵盖的任何内容:) 我知道 node.js 是单线程的，如果计时器花费太长时间，它们可能会阻塞其他计时器， 等等。
PS: I'm strictly trying to understand how viable is what I describe, no need to point out "there's surely a better way to do what you intend to do!".
PS：我严格地试图理解我所描述的内容有多可行，无需指出“肯定有更好的方法来做你想做的事！”。
回答by Sam Shiles
The only real world limit you may come up against is the amount of memory available to node. Use the following code to test. I successfully ran the example below using oneMillion and int32Max. When using int64Max, I received the following error from node. I'm using 64bit windows with 4gb of RAM.
您可能遇到的唯一现实世界限制是节点可用的内存量。使用以下代码进行测试。我使用 oneMillion 和 int32Max 成功运行了下面的示例。使用 int64Max 时，我从节点收到以下错误。我正在使用带有 4GB RAM 的 64 位 Windows。
FATAL ERROR: CALL_AND_RETRY_2 Allocation failed - process out of memory
Node code to test:
要测试的节点代码：
var util = require('util');
var int64Max = 9007199254740992;
var int32Max = 2147483647;
var oneMillion = 1000000;
var tenThousand = 10000;
var counter = 0;
//Exchange the limiter with one of the above vars to test.
for (var i = 0; i < oneMillion; i++){
setTimeout(log, 1);
//Required as the timeout/callback method will not be called until the loop ends due
//to node/js being single threaded.
util.log('loop:' + i);
}
function log(){
util.log('callback: ' + counter++);
}
回答by Jeremy J Starcher
I don't know how node operates, but if you create MAXINT+1 timers without letting them run, you risk an integer overflow.
我不知道节点是如何运行的，但是如果您创建 MAXINT+1 计时器而不让它们运行，则会冒整数溢出的风险。
