从 Node.JS 中未捕获的异常中恢复 [英] Recover from Uncaught Exception in Node.JS

问题描述

好的，所以我有问题.如果在处理 HTTP 请求时发生未捕获的异常，我将没有机会调用 http.ServerResponse 对象上的 end() 方法.因此，服务器永远挂起，永远不会满足请求.

OK, so I have a problem. If an uncaught exception occurs while I am handling an HTTP request, I have no opportunity to call the end() method on the http.ServerResponse object. Therefore, the server hangs forever and never fulfills the request.

这是一个例子:

var express = require('express');
var app = express.createServer();
var reqNum = 0;
app.get('/favicon.ico', function(req, res) {res.send(404);});
app.get('*', function(req, res, next) {
    console.log("Request #", ++reqNum, ":", req.url);
    next();
});
app.get('/error', function(req, res, next) {
    throw new Error("Problem occurred");
});
app.get('/hang', function(req, res, next) {
    console.log("In /hang route");
    setTimeout(function() {
        console.log("In /hang callback");
        if(reqNum >= 3)
            throw new Error("Problem occurred");
        res.send("It worked!");
    }, 2000);
});
process.on('uncaughtException', function(err) {
    console.log("Uncaught exception!", err);
});
app.listen(8080);

如果访问/error，会发生异常，但会被捕获.用户收到错误消息 - 没问题.但是，如果我访问/hang，服务器最终将抛出一个未捕获的异常并永远挂起.任何对/hang 的后续请求都将挂起.

If you visit /error, an exception occurs, but it is caught. The user receives an error message - no problem. If I visit /hang, though, the server will eventually throw an uncaught exception and hang forever. Any subsequent requests for /hang will hang.

这很糟糕.有关如何解决此问题的任何建议?

This sucks. Any advice for how to fix this issue?

推荐答案

当发生未捕获的异常时，您处于不干净的状态.让进程终止并重新启动它，没有其他办法可以安全地将其恢复到已知良好的状态.使用 forever，它会在它终止后立即重新启动您的进程.

When an uncaught exception occurs, you're in an unclean state. Let the process die and restart it, there's nothing else you can do to safely bring it back to a known-good state. Use forever, it'll restart your process as soon as it dies.

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