concurrent requets to servlet mix results

[sysuser1]

I have a servlet that uses PrintWriter out and then out.println() to output html code to clients. If some concurrent request are made, data is lost in some of them, and the same result is shown in these cases. In addition, I loose some data stored in an ArrayList (becomes null). For any of the problems, ¿any idea, suggestion, etc? thanks in advance

[petertje]

you are not using member variables in your servlet are you?
Servlets should be thread-safe. If they are not, you must explicitely configure this somewhere - i can't recall how and where, just check some servlet docs and you'll find out....

Hth
Peter

[haraldgliebe]

You can disable concurrent access to your servlet by implementing SingleThreadModel.