Senthamil Bharathi’s Weblog

Thread-safe Servlets

May 29, 2008 at 6:32 am (Uncategorized)

Identify which attribute scopes are thread-safe:

1. Local variables Yes, thread-safe
2. Instance variables Not thread-safe
   Since a single servlet instance may be handling multiple service requests at any given time.
3. Class variables Not thread-safe
   Since multiple servlets and /or service requests may try to access a class variable concurrently.
4. Request attributes Not thread-safe
   See the quote below.
5. Session attributes Not thread-safe
   Since sessions are scoped at the web application level, hence the same session object can be accessed concurrently by multiple servlets and their service requests
6. Context attributes Not thread-safe
   Since the same context object can be accessed concurrently by multiple servlets and their service requests