我得到以下警告:
(node) warning: possible EventEmitter memory leak detected. 11 listeners added. Use emitter.setMaxListeners() to increase limit.
Trace:
at EventEmitter.<anonymous> (events.js:139:15)
at EventEmitter.<anonymous> (node.js:385:29)
at Server.<anonymous> (server.js:20:17)
at Server.emit (events.js:70:17)
at HTTPParser.onIncoming (http.js:1514:12)
at HTTPParser.onHeadersComplete (http.js:102:31)
at Socket.ondata (http.js:1410:22)
at TCP.onread (net.js:354:27)
我在server.js中写了这样的代码:
http.createServer(
function (req, res) { ... }).listen(3013);
如何解决这个问题?
I prefer to hunt down and fix problems instead of suppressing logs whenever possible. After a couple days of observing this issue in my app, I realized I was setting listeners on the req.socket in an Express middleware to catch socket io errors that kept popping up. At some point, I learned that that was not necessary, but I kept the listeners around anyway. I just removed them and the error you are experiencing went away. I verified it was the cause by running requests to my server with and without the following middleware:
socketEventsHandler(req, res, next) {
req.socket.on("error", function(err) {
console.error('------REQ ERROR')
console.error(err.stack)
});
res.socket.on("error", function(err) {
console.error('------RES ERROR')
console.error(err.stack)
});
next();
}
删除该中间件将停止您所看到的警告。我会查看您的代码，并尝试找到您可能设置了不需要的侦听器的任何地方。
感谢RLaaa给了我一个如何解决警告的真正问题/根本原因的想法。在我的例子中，是MySQL有bug的代码。
假设你写了一个承诺，里面的代码是这样的:
pool.getConnection((err, conn) => {
if(err) reject(err)
const q = 'SELECT * from `a_table`'
conn.query(q, [], (err, rows) => {
conn.release()
if(err) reject(err)
// do something
})
conn.on('error', (err) => {
reject(err)
})
})
注意，代码中有一个conn.on('error')侦听器。代码一遍又一遍地添加监听器取决于调用查询的次数。
同时if(err) reject(err)做同样的事情。
所以我删除了conn.on('error')监听器，瞧…解决了!
希望这对你有所帮助。
