Selenium Webdriver requires restarts to function consistently - node.js

Question

My testing stack consists of the latest version of Selenium Server (2.33.0, aka selenium-server-standalone-2.33.0.jar), Mocha, Node.js, and PhantomJS.
My question regards the following code:
var webdriver = require('../../../lib/selenium/node_modules/selenium-webdriver/'),
driver = new webdriver.Builder().
withCapabilities({'browserName': 'phantomjs'}).
build();
driver.manage().timeouts().implicitlyWait(15000);
describe('Wordpress', function() {
it('should be able to log in', function(done) {
driver.get('http://#### REDACTED ####/wp-login.php');
driver.findElement(webdriver.By.css('#user_login')).sendKeys('#### REDACTED ####');
driver.findElement(webdriver.By.css('#user_pass')).sendKeys('#### REDACTED ####');
driver.findElement(webdriver.By.css('#wp-submit')).click();
// #wpwrap is an element on the Wordpress dashboard that is displayed once
// the user is logged in. By testing for its presence, we can determine
// if the login attempt succeeded.
driver.findElement(webdriver.By.css('#wpwrap')).then(function(v) {
done();
});
});
});
On my local system, OS X, the test runs fine consistently. However, once the test is uploaded to our CentOS server (where we hope to do Continuous Integration testing), the test behaves extremely strangely.
After Selenium Server is started, the test runs successfully once. From that point on, the test only succeeds every one out of ten times or so. Restarting Selenium Server guarantees that the test will run successfully. In fact, if Selenium Server is restarted every time the test is run, the test will succeed every time.
How can I get this test to succeed without restarting Selenium Server every time?
Thank you so much for your help! :)
UPDATE: In addition to the error log below, I'm also occasionally getting the following error:
Exception in thread "Thread-21" java.lang.OutOfMemoryError: unable to create new native thread
Details on the error messages follow below:
A successful test yields the following output from Mocha:
[s5rich#host ~]$ mocha test/selenium/acceptance/simple.js
Wordpress
✓ should be able to log in (2604ms)
1 passing (3 seconds)
A successful test also yields the following output from Selenium Server:
23:21:50.517 INFO - Executing: [new session: {browserName=phantomjs}] at URL: /session)
23:21:50.527 INFO - Creating a new session for Capabilities [{browserName=phantomjs}]
23:21:50.547 INFO - executable: /usr/local/bin/phantomjs
23:21:50.547 INFO - port: 26515
23:21:50.547 INFO - arguments: [--webdriver=26515, --webdriver-logfile=/home/s5rich/phantomjsdriver.log]
23:21:50.547 INFO - environment: {}
PhantomJS is launching GhostDriver...
[INFO - 2013-07-24T05:21:50.923Z] GhostDriver - Main - running on port 26515
[INFO - 2013-07-24T05:21:51.435Z] Session [f235d040-f420-11e2-8d90-f50327bc3449] - CONSTRUCTOR - Desired Capabilities: {"browserName":"phantomjs"}
[INFO - 2013-07-24T05:21:51.435Z] Session [f235d040-f420-11e2-8d90-f50327bc3449] - CONSTRUCTOR - Negotiated Capabilities: {"browserName":"phantomjs","version":"1.9.1","driverName":"ghostdriver","driverVersion":"1.0.3","platform":"linux-unknown-32bit","javascriptEnabled":true,"takesScreenshot":true,"handlesAlerts":false,"databaseEnabled":false,"locationContextEnabled":false,"applicationCacheEnabled":false,"browserConnectionEnabled":false,"cssSelectorsEnabled":true,"webStorageEnabled":false,"rotatable":false,"acceptSslCerts":false,"nativeEvents":true,"proxy":{"proxyType":"direct"}}
[INFO - 2013-07-24T05:21:51.435Z] SessionManagerReqHand - _postNewSessionCommand - New Session Created: f235d040-f420-11e2-8d90-f50327bc3449
23:21:51.495 INFO - Done: /session
23:21:51.504 INFO - Executing: org.openqa.selenium.remote.server.handler.GetSessionCapabilities#46b78d at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2)
23:21:51.505 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2
23:21:51.520 INFO - Executing: [get: http://#### REDACTED ####/wp-login.php] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/url)
23:21:51.821 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/url
23:21:51.827 INFO - Executing: [find element: By.selector: #user_login] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element)
23:21:51.874 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element
23:21:51.883 INFO - Executing: [send keys: 0 org.openqa.selenium.support.events.EventFiringWebDriver$EventFiringWebElement#20788bf8, [#### REDACTED ####]] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element/0/value)
23:21:51.939 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element/0/value
23:21:51.948 INFO - Executing: [find element: By.selector: #user_pass] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element)
23:21:51.965 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element
23:21:52.001 INFO - Executing: [send keys: 1 org.openqa.selenium.support.events.EventFiringWebDriver$EventFiringWebElement#20788bf9, [#### REDACTED ####]] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element/1/value)
23:21:52.065 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element/1/value
23:21:52.074 INFO - Executing: [find element: By.selector: #wp-submit] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element)
23:21:52.099 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element
23:21:52.106 INFO - Executing: [click: 2 org.openqa.selenium.support.events.EventFiringWebDriver$EventFiringWebElement#20788bfa] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element/2/click)
23:21:52.842 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element/2/click
23:21:52.850 INFO - Executing: [find element: By.selector: #wpwrap] at URL: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element)
23:21:52.871 INFO - Done: /session/8750a6b4-ec7d-4313-a86d-04ac344b74f2/element
A failed test yields the following output from Mocha:
[s5rich#host ~]$ mocha test/selenium/acceptance/simple.js
Wordpress
1) should be able to log in
0 passing (2 seconds)
1 failing
1) Wordpress should be able to log in:
Uncaught UnknownError: Error Message => 'Unable to find element with css selector '#wpwrap''
caused by Request => {"headers":{"Accept":"application/json, image/png","Connection":"Keep-Alive","Content-Length":"42","Content-Type":"application/json; charset=utf-8","Host":"localhost:2897"},"httpVersion":"1.1","method":"POST","post":"{\"using\":\"css selector\",\"value\":\"#wpwrap\"}","url":"/element","urlParsed":{"anchor":"","query":"","file":"element","directory":"/","path":"/element","relative":"/element","port":"","host":"","password":"","user":"","userInfo":"","authority":"","protocol":"","source":"/element","queryKey":{},"chunks":["element"]},"urlOriginal":"/session/77a0a110-f421-11e2-a6fd-61cd002d7d02/element"}
Build info: version: '2.33.0', revision: '4e90c97', time: '2013-05-22 15:32:38'
System info: os.name: 'Linux', os.arch: 'i386', os.version: '2.6.32-042stab076.8', java.version: '1.7.0'
Driver info: driver.version: unknown
at new bot.Error (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/atoms/error.js:108:18)
at Object.bot.response.checkResponse (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/atoms/response.js:106:9)
at /home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/webdriver.js:262:20
at /home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/goog/base.js:1112:15
at webdriver.promise.ControlFlow.runInNewFrame_ (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:1431:20)
at notify (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:315:12)
at notifyAll (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:284:7)
at fulfill (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:389:7)
at /home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:1298:10
at /home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/goog/base.js:1112:15
at webdriver.promise.ControlFlow.runInNewFrame_ (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:1431:20)
at notify (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:315:12)
at notifyAll (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:284:7)
at fulfill (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:389:7)
at /home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/goog/base.js:1112:15
at webdriver.promise.ControlFlow.runInNewFrame_ (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:1431:20)
at notify (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:315:12)
at notifyAll (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:284:7)
at fulfill (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:389:7)
at /home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/promise.js:600:51
at /home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/http/http.js:96:5
at IncomingMessage.<anonymous> (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/http/index.js:113:7)
at IncomingMessage.EventEmitter.emit (events.js:117:20)
at _stream_readable.js:910:16
at process._tickCallback (node.js:415:13)
==== async task ====
WebDriver.findElement(By.cssSelector("#wpwrap"))
at webdriver.WebDriver.schedule (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/webdriver.js:246:15)
at webdriver.WebDriver.findElement (/home/s5rich/lib/selenium/node_modules_osx/selenium-webdriver/lib/webdriver/webdriver.js:685:17)
at Context.<anonymous> (/home/s5rich/test/selenium/acceptance/simple.js:12:10)
at Test.Runnable.run (/usr/local/lib/node_modules/mocha/lib/runnable.js:194:15)
at Runner.runTest (/usr/local/lib/node_modules/mocha/lib/runner.js:355:10)
at /usr/local/lib/node_modules/mocha/lib/runner.js:401:12
at next (/usr/local/lib/node_modules/mocha/lib/runner.js:281:14)
at /usr/local/lib/node_modules/mocha/lib/runner.js:290:7
at next (/usr/local/lib/node_modules/mocha/lib/runner.js:234:23)
at Object._onImmediate (/usr/local/lib/node_modules/mocha/lib/runner.js:258:5)
at processImmediate [as _immediateCallback] (timers.js:330:15)
A failed test also yields the following output from Selenium Server:
23:25:34.742 INFO - Executing: [new session: {browserName=phantomjs}] at URL: /session)
23:25:34.743 INFO - Creating a new session for Capabilities [{browserName=phantomjs}]
23:25:34.744 INFO - executable: /usr/local/bin/phantomjs
23:25:34.744 INFO - port: 2897
23:25:34.744 INFO - arguments: [--webdriver=2897, --webdriver-logfile=/home/s5rich/phantomjsdriver.log]
23:25:34.744 INFO - environment: {}
PhantomJS is launching GhostDriver...
[INFO - 2013-07-24T05:25:34.879Z] GhostDriver - Main - running on port 2897
[INFO - 2013-07-24T05:25:35.270Z] Session [77a0a110-f421-11e2-a6fd-61cd002d7d02] - CONSTRUCTOR - Desired Capabilities: {"browserName":"phantomjs"}
[INFO - 2013-07-24T05:25:35.270Z] Session [77a0a110-f421-11e2-a6fd-61cd002d7d02] - CONSTRUCTOR - Negotiated Capabilities: {"browserName":"phantomjs","version":"1.9.1","driverName":"ghostdriver","driverVersion":"1.0.3","platform":"linux-unknown-32bit","javascriptEnabled":true,"takesScreenshot":true,"handlesAlerts":false,"databaseEnabled":false,"locationContextEnabled":false,"applicationCacheEnabled":false,"browserConnectionEnabled":false,"cssSelectorsEnabled":true,"webStorageEnabled":false,"rotatable":false,"acceptSslCerts":false,"nativeEvents":true,"proxy":{"proxyType":"direct"}}
[INFO - 2013-07-24T05:25:35.270Z] SessionManagerReqHand - _postNewSessionCommand - New Session Created: 77a0a110-f421-11e2-a6fd-61cd002d7d02
23:25:35.275 INFO - Done: /session
23:25:35.283 INFO - Executing: org.openqa.selenium.remote.server.handler.GetSessionCapabilities#13b4ce4 at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee)
23:25:35.284 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee
23:25:35.297 INFO - Executing: [get: http://#### REDACTED ####/wp-login.php] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/url)
23:25:35.592 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/url
23:25:35.597 INFO - Executing: [find element: By.selector: #user_login] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element)
23:25:35.619 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element
23:25:35.631 INFO - Executing: [send keys: 0 org.openqa.selenium.support.events.EventFiringWebDriver$EventFiringWebElement#240035bc, [#### REDACTED ####]] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element/0/value)
23:25:35.683 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element/0/value
23:25:35.695 INFO - Executing: [find element: By.selector: #user_pass] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element)
23:25:35.712 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element
23:25:35.723 INFO - Executing: [send keys: 1 org.openqa.selenium.support.events.EventFiringWebDriver$EventFiringWebElement#240035bd, [#### REDACTED ####]] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element/1/value)
23:25:35.783 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element/1/value
23:25:35.800 INFO - Executing: [find element: By.selector: #wp-submit] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element)
23:25:35.822 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element
23:25:35.832 INFO - Executing: [click: 2 org.openqa.selenium.support.events.EventFiringWebDriver$EventFiringWebElement#240035be] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element/2/click)
23:25:36.105 INFO - Done: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element/2/click
23:25:36.121 INFO - Executing: [find element: By.selector: #wpwrap] at URL: /session/b62d0c67-2000-439c-a0bd-f2c100350dee/element)
e = java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
23:25:36.285 WARN - Exception thrown
org.openqa.selenium.NoSuchElementException: Error Message => 'Unable to find element with css selector '#wpwrap''
caused by Request => {"headers":{"Accept":"application/json, image/png","Connection":"Keep-Alive","Content-Length":"42","Content-Type":"application/json; charset=utf-8","Host":"localhost:2897"},"httpVersion":"1.1","method":"POST","post":"{\"using\":\"css selector\",\"value\":\"#wpwrap\"}","url":"/element","urlParsed":{"anchor":"","query":"","file":"element","directory":"/","path":"/element","relative":"/element","port":"","host":"","password":"","user":"","userInfo":"","authority":"","protocol":"","source":"/element","queryKey":{},"chunks":["element"]},"urlOriginal":"/session/77a0a110-f421-11e2-a6fd-61cd002d7d02/element"}
Command duration or timeout: 149 milliseconds
For documentation on this error, please visit: http://seleniumhq.org/exceptions/no_such_element.html
Build info: version: '2.33.0', revision: '4e90c97', time: '2013-05-22 15:32:38'
System info: os.name: 'Linux', os.arch: 'i386', os.version: '2.6.32-042stab076.8', java.version: '1.7.0'
Session ID: 77a0a110-f421-11e2-a6fd-61cd002d7d02
Driver info: org.openqa.selenium.phantomjs.PhantomJSDriver
Capabilities [{platform=LINUX, acceptSslCerts=false, javascriptEnabled=true, browserName=phantomjs, rotatable=false, driverVersion=1.0.3, locationContextEnabled=false, version=1.9.1, databaseEnabled=false, cssSelectorsEnabled=true, handlesAlerts=false, browserConnectionEnabled=false, proxy={proxyType=direct}, webStorageEnabled=false, nativeEvents=true, driverName=ghostdriver, applicationCacheEnabled=false, takesScreenshot=true}]
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.openqa.selenium.remote.ErrorHandler.createThrowable(ErrorHandler.java:191)
at org.openqa.selenium.remote.ErrorHandler.throwIfResponseFailed(ErrorHandler.java:145)
at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:554)
at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:307)
at org.openqa.selenium.remote.RemoteWebDriver.findElementByCssSelector(RemoteWebDriver.java:396)
at org.openqa.selenium.By$ByCssSelector.findElement(By.java:407)
at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:299)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.openqa.selenium.support.events.EventFiringWebDriver$2.invoke(EventFiringWebDriver.java:101)
at $Proxy1.findElement(Unknown Source)
at org.openqa.selenium.support.events.EventFiringWebDriver.findElement(EventFiringWebDriver.java:180)
at org.openqa.selenium.remote.server.handler.FindElement.call(FindElement.java:47)
at org.openqa.selenium.remote.server.handler.FindElement.call(FindElement.java:1)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at org.openqa.selenium.remote.server.DefaultSession$1.run(DefaultSession.java:169)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: org.openqa.selenium.remote.ScreenshotException: Screen shot has been taken
Build info: version: '2.33.0', revision: '4e90c97', time: '2013-05-22 15:32:38'
System info: os.name: 'Linux', os.arch: 'i386', os.version: '2.6.32-042stab076.8', java.version: '1.7.0'
Driver info: driver.version: EventFiringWebDriver
at org.openqa.selenium.remote.ErrorHandler.throwIfResponseFailed(ErrorHandler.java:125)
... 20 more
Caused by: org.openqa.selenium.remote.ErrorHandler$UnknownServerException: Error Message => 'Unable to find element with css selector '#wpwrap''
caused by Request => {"headers":{"Accept":"application/json, image/png","Connection":"Keep-Alive","Content-Length":"42","Content-Type":"application/json; charset=utf-8","Host":"localhost:2897"},"httpVersion":"1.1","method":"POST","post":"{\"using\":\"css selector\",\"value\":\"#wpwrap\"}","url":"/element","urlParsed":{"anchor":"","query":"","file":"element","directory":"/","path":"/element","relative":"/element","port":"","host":"","password":"","user":"","userInfo":"","authority":"","protocol":"","source":"/element","queryKey":{},"chunks":["element"]},"urlOriginal":"/session/77a0a110-f421-11e2-a6fd-61cd002d7d02/element"}
Build info: version: '2.33.0', revision: '4e90c97', time: '2013-05-22 15:32:38'
System info: os.name: 'Linux', os.arch: 'i386', os.version: '2.6.32-042stab076.8', java.version: '1.7.0'
Driver info: driver.version: unknown
23:25:36.293 WARN - Exception: Error Message => 'Unable to find element with css selector '#wpwrap''
caused by Request => {"headers":{"Accept":"application/json, image/png","Connection":"Keep-Alive","Content-Length":"42","Content-Type":"application/json; charset=utf-8","Host":"localhost:2897"},"httpVersion":"1.1","method":"POST","post":"{\"using\":\"css selector\",\"value\":\"#wpwrap\"}","url":"/element","urlParsed":{"anchor":"","query":"","file":"element","directory":"/","path":"/element","relative":"/element","port":"","host":"","password":"","user":"","userInfo":"","authority":"","protocol":"","source":"/element","queryKey":{},"chunks":["element"]},"urlOriginal":"/session/77a0a110-f421-11e2-a6fd-61cd002d7d02/element"}
Build info: version: '2.33.0', revision: '4e90c97', time: '2013-05-22 15:32:38'
System info: os.name: 'Linux', os.arch: 'i386', os.version: '2.6.32-042stab076.8', java.version: '1.7.0'
Driver info: driver.version: unknown

Answer 1

From what I see, it is a simple problem to solve. You have a unhandled exception that is being thrown when there is a failure: NoSuchElementException . I don't think you need to restart your grid node every time (assuming you are running your grid hub separate from your grid node instances). It may be that successive runs of the browser from your Grid Node use just enough more memory to cause a minor delay in the page, breaking your script. All you need to do is handle the NoSuchElementException gracefully by wrapping it in a retry try loop. You can also effectively do similar using FluentWait with the .ignoring method.