Unable to get Selenium Grid 3.0.1 running on multiple instances of Chrome

Question

I have recently moved from Selenium Grid 2.48 to 3.0.1 but I am having problems getting tests to run on multiple instances of Chrome.

It appears that when Selenium Grid changed from v2 to v3 that Chrome's default browser instances changed from five to one. In v2 I had no problems running our C#/NUnit3 tests in parallel on the default five Chrome instances.

However, since moving to v3 I can't get more than a single thread to run per node. I can start the node with maxInstances=5, and can see them in the the grid console. The grid console displays this message "4 requests waiting for a slot to be free." even though there are four instances idle.

My Grid config is as below:

Hub

java -jar selenium-server-standalone-3.0.1.jar -role hub -newSessionWaitTimeout -1 -maxSession 50 -browserTimeout 90  -timeout 100

Node

java -jar selenium-server-standalone-3.0.1.jar -port 5556 -role node -hub http://host:4444/grid/register  -browser browserName=chrome,maxInstances=5

If I use selenium-server-standalone-2.48.2.jar everything works as expected even though the the test are written using v3 WebDriver and WebDriver.Support dll's.

Answer 1

You should use -maxSession parameter on your node, see if it helps. It seems that on v3 maxSession defaults to 1 which means you can't run it in parallel unless you set maxSession property on wanted number.

maxSession is a number of (any) browser instances which can run in parallel.