GVN,
Let's make it simple: Say you have an app that needs to get rss feeds from
1000 sites once every hour.  You can serialize it by having one thread go
through all 1000 requests one at a time, or you can do it asynchronously on a
threadpool with say 30 threads, in which case you will have 30 requests going
simultaneously and as soon as a thread has finished it will pick up a new
request. This may not turn out to be exactly 30 times faster than the first
case, but I think you get the idea.

Disadvantages? You have to understand how to do it correctly, and that takes
some study.
Peter

Hello, GVN!

G>     Can anyone guide me when asynchronous method calls will be
G> benificial?

Its up to app design. Async method calls are used when the caller
knows that operation will take a while, so she doesn't wait for method to complete
and instead can do some more usefull job ( render UI etc ).

Good example is network I/O. If you have GUI application it will not be good if UI
freezes every time you're receiving or sending data, right?

G> Are there any disadvantages of using asynchronous calls?
Usually making synchronous call is faster that async one.
This statement is valid only of method execution time is relatively small...

--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com

The BackgroundWorker class makes implementing asynch methods a breeze.
Take a look at the page below it gives a decent explanation of why you
would use asynch calls and how to use the BackgroundWorker class.

http://msdn2.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx

cheers

Steve

There have been some replies that confuse multithreading with asynchronous
method calls.  The two aren't the same.  Threadpools and backgroundworker
threads are great but, they don't solve the same problems that async method
calls can solve.

Another reply gave an example of checking 1000 RSS feeds with a pool of 30
threads.  The asynchronous approach would be to issue 1000 BeginRead() so
you have 1000 outstanding async calls then, as the reads complete, the
AsyncCallback method is called.

If you were writing a CHAT server, you could create a new thread for each
client but, that wouldn't scale very far.  With an async approach, you would
call BeginRead() for each client then, when the read completes, the
AsyncCallback would call BeginWrite() for each client that the incoming
message should be directed to and then call BeginRead() again to replace the
read that just completed.  This would scale to thousands of clients with
just a few threads.