If i login with different users into my application in two different tabs with in same browser then i am getting first login data in these two tabs so how can i rectify this problem? how can i avoid concurrency while implementing webapplications?
Really? Won't needing to take turns getting a shot on the keyboard make this sort of working prohibitively difficult?
if two users are using my application in different browsers with same login credentails then Are they get mismatch in data? if so how can i avoid that?
That's a different question. The answer is you can't, unless you prevent the second user logging in while the first user is using their credentials. Where you have two users accessing the same shared data you need to use techniques such as locking to prevent data loss. Seeing potentially out of date data in a web application is just a necessary fact of life, you need to write your application logic to be aware that this can and will happen.