selenium-webdriver - TestNG と Grid 2 で並列テストを実行すると、テストが失敗するのはなぜですか?

Question

皆さん、助けていただければ幸いです。よろしくお願いします。Webdriver と TestNG で 10 個のテストを作成し、Grid2 で実行します。1ノードを起動すると、すべてのテストに合格しました。2ノード起動すると、並列に動作します。しかし、いくつかのテストは失敗しました。次のようなエラー:

org.openqa.selenium.WebDriverException: unknown error: cannot focus element

私のステップ:

1.ハブを起動

D:\Selenium>java -jar selenium-server-standalone-2.35.0.jar -role hub
2.Start Node 1

D:\Selenium>java -jar selenium-server-standalone-2.35.0.jar -role wd -port 5556 -hub ip/grid/register  -Dwebdriver.chrome.driver=D:\Selenium\chromedriver.exe -browser "browserName=chrome,maxInstances=1,platform=WINDOWS"

3.ノード 2 の起動

C:\Selenium>java -jar selenium-server-standalone-2.35.0.jar -role wd -hub ip/grid/register  -Dwebdriver.chrome.driver=C:\Selenium\chromedriver.exe -browser "browserName=chrome,maxInstances=1,platform=WINDOWS"

4.次にテストtestng.xmlを実行します

   <!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">

    <suite name="LoginTest" verbose="4" parallel="methods" thread-count="10">

<test name="Login">
    <classes>
        <class name="com.ms.gridDemo.test.LoginTest">
        </class>
    </classes>
</test>
<test name="Login2">
    <classes>
        <class name="com.ms.gridDemo.test.LoginTest2">
        </class>
    </classes>
</test>

テスト ケース ベース:

package com.ms.gridDemo.test;
import java.net.MalformedURLException;
import java.net.URL;

import junit.framework.Assert;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.remote.RemoteWebDriver;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.annotations.AfterClass;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.AfterMethod;

import com.google.common.base.Function;

public class AbstractTest {
private WebDriver driver = null;
private String baseURL;

public void login() throws InterruptedException {
  driver.get(baseURL);
  waitForElementVisible(driver,By.id("email"));
  WebElement emailElem = driver.findElement(By.id("email"));
  WebElement passwordElem = driver.findElement(By.id("password"));
  emailElem.clear();
  emailElem.sendKeys("jeff.liang@ms.com");
  passwordElem.clear();
  passwordElem.sendKeys("!Q@W3e4r");
  WebElement submitEl = driver.findElement(By.id("submit_btn"));
  submitEl.click();
  Thread.sleep(2000);
  Assert.assertFalse("Login failed.",IsTextPresent(driver,"The Email address or password you entered is incorrect."));
  ;
  }

  @BeforeMethod
  public void beforeMethod() {
  DesiredCapabilities dc = DesiredCapabilities.chrome();
  URL url = null;
try {
    url = new URL("http://localhost:4444/wd/hub");
} catch (MalformedURLException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
  driver =new RemoteWebDriver(url, dc);
  driver.manage().window().maximize();
  baseURL ="https://mercury-uat.morningstar.com";
   }

@AfterMethod
 public void afterMethod() {
  driver.quit();
 }

public static WebElement waitForElementVisible(WebDriver driver, final By locator) {
    Function<WebDriver, WebElement> waitFn = new Function<WebDriver, WebElement>() {
        @Override
        public WebElement apply(WebDriver driver) {
            try {
                WebElement el = driver.findElement(locator);
                if (el.isDisplayed()) {
                    return el;
                }
            } catch (Exception e) {
            }
            return null;
        }
    };

    WebDriverWait wait = new WebDriverWait(driver,120,300);
    return wait.until(waitFn);
}

public boolean IsTextPresent(WebDriver driver, String text) {
    try {
        return driver.getPageSource().contains(text);
    } catch (Exception e) {
        return false;
    }
}

 }

================================================== =========================

テストクラス 1:

  package com.ms.gridDemo.test;

  import org.testng.annotations.Test;

  import com.ms.gridDemo.test.AbstractTest;

 public class LoginTest extends AbstractTest {
  @Test
 public void test1() throws InterruptedException {
  login();
}   

 @Test
 public void test2() throws InterruptedException {
  login();
 }  

 @Test
 public void test3() throws InterruptedException {
  login();
 }  

 @Test
public void test4() throws InterruptedException {
  login();
 }  
 @Test
 public void test5() throws InterruptedException {
  login();
 }  
}

================================================== ==============

テストクラス 2

     package com.ms.gridDemo.test;

   import org.testng.annotations.Test;

import com.ms.gridDemo.test.AbstractTest;

  public class LoginTest2 extends AbstractTest {
  @Test
  public void test6() throws InterruptedException {
  login();
 }  

  @Test
 public void test7() throws InterruptedException {
  login();
  } 

  @Test
 public void test8() throws InterruptedException {
  login();
 }  

  @Test
  public void test9() throws InterruptedException {
  login();
    }   
  @Test
 public void test10() throws InterruptedException {
  login();
 }  
     }