(node) warning: possible EventEmitter memory leak detected. 11 job ttl exceeded ack listeners added

(node) warning: possible EventEmitter memory leak detected. 11 job ttl exceeded ack listeners added. Use emitter.setMaxListeners() to increase limit.
Trace
    at Queue.addListener (events.js:239:17)
    at Queue.on (/mnt/app/node_modules/kue/lib/kue.js:130:13)
    at Command.callback (/mnt/app/node_modules/kue/lib/kue.js:234:16)
    at RedisClient.return_reply (/mnt/app/node_modules/redis/index.js:664:25)
    at HiredisReplyParser.reply_parser.send_reply (/mnt/app/node_modules/redis/index.js:332:14)
    at HiredisReplyParser.execute (/mnt/app/node_modules/redis/lib/parsers/hiredis.js:30:18)
    at Socket.<anonymous> (/mnt/app/node_modules/redis/index.js:131:27)
    at emitOne (events.js:77:13)
    at Socket.emit (events.js:169:7)
    at readableAddChunk (_stream_readable.js:146:16)
    at Socket.Readable.push (_stream_readable.js:110:10)
    at TCP.onread (net.js:523:20)

Is this warning just related to the number of jobs that have TTL expiring? We can use emitter.setMaxListeners() to increase this value and prevent the warning, but I’m curious about the root cause.

[Davounet]

I’m running into the same warning when the total amount of jobs (their concurrency value actually) exceeds 10. It doesn’t seem to be anything bad, only a warning, but it’s quite annoying seeing this poping up.

[popey456963]

@Shadowys The warning isn’t an issue in this use case. You’re expecting over ten event listeners, so it’s not a memory leak.

You can do some prototype hacks to avoid the error:

// 0 = infinite listeners
require('events').EventEmitter.prototype._maxListeners = 0;