jsforce: "possible EventEmitter memory leak detected" still occurring after upgrading to 1.5.1

We are still seeing the memory leak logs mentioned in #247 after upgrading to v1.5.1. They are pretty frequent whenever we are actively using jsforce methods, and usually look something like this:

(node) warning: possible EventEmitter memory leak detected. 11 value listeners added. Use emitter.setMaxListeners() to increase limit.
Trace
    at addListener (events.js:239:17)
    at Tooling.initialize (/opt/project/node_modules/jsforce/lib/api/tooling.js:63:36)
    at Connection.initialize (/opt/project/node_modules/jsforce/lib/connection.js:229:18)
    at /opt/project/node_modules/jsforce/lib/connection.js:1073:10
    at /opt/project/node_modules/jsforce/node_modules/promise/lib/core.js:33:15
    at flush (/opt/project/node_modules/jsforce/node_modules/promise/node_modules/asap/asap.js:27:13)
    at nextTickCallbackWith0Args (node.js:419:9)
    at process._tickCallback (node.js:348:13)

This is running on node v4.3.0, and manifested after upgrading from node v0.10… it was also happening in node v0.12 which is why we were aware of it and had upgraded to jsforce@1.5.1, but we still have the error in our logs pretty frequently.

About this issue

Original URL
State: open
Created 8 years ago
Reactions: 3
Comments: 18 (7 by maintainers)

Commits related to this issue

Fixed issue #356 - "possible EventEmitter memory leak detected" still occurring after upgrading to 1.5.1 — committed to czerwinskilukasz1/jsforce by czerwinskilukasz1 6 years ago
Merge pull request #792 from czerwinskilukasz1/master Fixed issue #356 - "possible EventEmitter memory leak detected" still… — committed to jsforce/jsforce by stomita 6 years ago

Most upvoted comments

Hello, the issue problem still persists. I run into it when I re-login every hour to maintain an active connection with Salesforce before session id expires. After ~10 relogins 2 warnings show up. Please find stack traces (node --trace-warnings).

Stack trace 1: MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 value listeners added. Use emitter.setMaxListeners() to increase limit at _addListener (events.js:280:19) at CacheEntry.addListener (events.js:297:10) at Tooling.initialize (/home/nodejs/enegive-ocpp-dev/node_modules/node-salesforce/lib/tooling.js:62:36) at module.exports.Connection.initialize (/home/nodejs/enegive-ocpp-dev/node_modules/node-salesforce/lib/connection.js:174:16) at /home/nodejs/enegive-ocpp-dev/node_modules/node-salesforce/lib/connection.js:851:10 at _fulfilled (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:798:54) at self.promiseDispatch.done (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:827:30) at Promise.promise.promiseDispatch (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:760:13) at /home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:574:44 at flush (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:108:17) at _combinedTickCallback (internal/process/next_tick.js:131:7) at process._tickDomainCallback (internal/process/next_tick.js:218:9)

Stack trace 2: (node:19516) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 value listeners added. Use emitter.setMaxListeners() to increase limit at _addListener (events.js:280:19) at CacheEntry.addListener (events.js:297:10) at module.exports.Connection.initialize (/home/nodejs/enegive-ocpp-dev/node_modules/node-salesforce/lib/connection.js:167:36) at /home/nodejs/enegive-ocpp-dev/node_modules/node-salesforce/lib/connection.js:851:10 at _fulfilled (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:798:54) at self.promiseDispatch.done (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:827:30) at Promise.promise.promiseDispatch (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:760:13) at /home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:574:44 at flush (/home/nodejs/enegive-ocpp-dev/node_modules/q/q.js:108:17) at _combinedTickCallback (internal/process/next_tick.js:131:7) at process._tickDomainCallback (internal/process/next_tick.js:218:9)

So the issue in both cases is re-adding a listener on ‘value’ event for ‘describeGlobal’ key in Cache (jsforce/lib/cache.js). Clearing the cache does NOT remove the listeners because the CacheEntry objects are NOT removed, just their values are deinitialized (delete this._value). The solution proposed here is to remove the previous ‘value’ event listener just before declaring a new one. Please check my pull request: https://github.com/jsforce/jsforce/pull/792

czerwinskilukasz1 on Aug 3, 2018