webdriverio: MaxListenersExceededWarning: Possible EventEmitter memory leak detected

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Environment (please complete the following information):

WebdriverIO version: 5.7.14
Mode: WDIO Testrunner
If WDIO Testrunner, running sync/async: sync
Node.js version: 10.9.0
NPM version: 6.2.0
Browser name and version: Chrome 74
Platform name and version: Windows NT 10
Additional wdio packages used (if applicable): @wdio/junit-reporter, @wdio/cli, @wdio/mocha-framework, @wdio/local-runner, @wdio/spec-reporter, @wdio/sync

Describe the bug During my CI build I’m seeing this happen. The build continues as normal after this

(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 end listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 unpipe listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 drain listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 error listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 close listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 finish listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 unpipe listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 drain listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 error listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 close listeners added. Use emitter.setMaxListeners() to increase limit
(node:4488) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 finish listeners added. Use emitter.setMaxListeners() to increase limit

To Reproduce Not really sure, I’m only seeing it in my CI pipeline.

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 18 (13 by maintainers)

Most upvoted comments

Fixing

mgrybyk on Apr 24, 2019

@mgrybyk Hello, i have the same problem on wdio 8.

(node:215) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 unpipe listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit

and then error Command failed with exit code 137.

can you please check

dkuznetsov21 on Aug 16, 2023

Those logs are from CircleCI. I can’t replicate that running locally, but I’m getting that warning for all the specs in CIrcleCI.

(Mocha framework) Capabilities:

  capabilities: [{
    // capabilities for local browser web tests
    maxInstances: 1,
    browserName: 'chrome', // or "firefox", "microsoftedge", "safari"
    browserVersion: `${process.env.CHROME_DRIVER}`,
    acceptInsecureCerts: true,
    'goog:chromeOptions': {
      // args: ['--start-maximized', '--enable-automation']
      args: [
        '--no-sandbox',
        '--disable-infobars',
        '--disable-extensions',
        '--disable-dev-shm-usage',
        '--enable-automation',
        '115.0.5790.170',
        '--window-size=1920,1080',
        '--disable-gpu'
      ],
      // Sets up the directory where the downloaded files will be stored.
      prefs: {
        'download.default_directory': global.downloadDir,
        'profile.default_content_setting_values.automatic_downloads': 1
      }
    }
  }],

package.json:

  "devDependencies": {
    "@babel/register": "^7.22.5",
    "@eslint/eslintrc": "^2.1.2",
    "@eslint/js": "^8.47.0",
    "@wdio/allure-reporter": "^8.15.0",
    "@wdio/cli": "^8.15.5",
    "@wdio/local-runner": "^8.15.4",
    "@wdio/mocha-framework": "^8.15.4",
    "@wdio/spec-reporter": "^8.15.0",
    "chai": "^4.3.7",
    "cross-env": "^7.0.3",
    "eslint": "^8.47.0",
    "eslint-plugin-import": "^2.28.0",
    "eslint-plugin-wdio": "^8.8.7",
    "eslint-plugin-yml": "^1.8.0",
    "mocha-multi": "^1.1.7"
  },
  "dependencies": {
    "@faker-js/faker": "^8.0.2",
    "allure-js-commons": "^2.0.0-beta.19",
    "allure-mocha": "^2.0.0-beta.19",
    "authenticator": "^1.1.5",
    "axios": "^1.4.0",
    "camelize": "^1.0.1",
    "dotenv": "^16.3.1",
    "eslint-config-airbnb-base": "^15.0.0",
    "eslint-plugin-simple-import-sort": "^10.0.0",
    "moment": "^2.29.4",
    "pdf-parse": "^1.1.1"
  }

deyvisPedrosa on Aug 17, 2023

When using node --trace-warnings flag:

> ui-automation@2.0.0 vendorDocs
> npx cross-env NODE_OPTIONS=--trace-warnings wdio run wdio.conf.js --suite vendorDocs


Execution of 2 workers started at 2023-08-14T21:21:02.628Z

(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 unpipe listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.addListener (node:events:606:10)
    at Readable.on (node:internal/streams/readable:887:35)
    at Readable.pipe (node:internal/streams/readable:692:8)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:15:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 error listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.prependListener (node:events:620:14)
    at prependListener (node:internal/streams/legacy:100:20)
    at Readable.pipe (node:internal/streams/readable:791:3)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:15:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 close listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.addListener (node:events:606:10)
    at Readable.on (node:internal/streams/readable:887:35)
    at WriteStream.once (node:events:650:8)
    at Readable.pipe (node:internal/streams/readable:798:8)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:15:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 finish listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.addListener (node:events:606:10)
    at Readable.on (node:internal/streams/readable:887:35)
    at WriteStream.once (node:events:650:8)
    at Readable.pipe (node:internal/streams/readable:804:8)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:15:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 unpipe listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.addListener (node:events:606:10)
    at Readable.on (node:internal/streams/readable:887:35)
    at Readable.pipe (node:internal/streams/readable:692:8)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:16:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 error listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.prependListener (node:events:620:14)
    at prependListener (node:internal/streams/legacy:100:20)
    at Readable.pipe (node:internal/streams/readable:791:3)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:16:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 close listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.addListener (node:events:606:10)
    at Readable.on (node:internal/streams/readable:887:35)
    at WriteStream.once (node:events:650:8)
    at Readable.pipe (node:internal/streams/readable:798:8)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:16:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
(node:1469) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 19 finish listeners added to [WriteStream]. Use emitter.setMaxListeners() to increase limit
    at _addListener (node:events:588:17)
    at WriteStream.addListener (node:events:606:10)
    at Readable.on (node:internal/streams/readable:887:35)
    at WriteStream.once (node:events:650:8)
    at Readable.pipe (node:internal/streams/readable:804:8)
    at file:///home/circleci/project/node_modules/@wdio/local-runner/build/worker.js:16:14
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)

deyvisPedrosa on Aug 17, 2023