Java EE (Java Enterprise Edition) General Discussion

Hi all, I am not sure writing to right place and ask for
I made a jsp servlet java application and there is something bear in my mind.
My application has a converter (all java classes) for media files (like wmv, mpg) uploded by clients.
If needed converter start to proses (request came from servlet where uploed is done using by apache commons)right after uploding. My question is;
If more than one user uplodes file at same time and need convert for these files,
Does converter run for them at same time or Do i have to put a thread for converter?
Clasically my application has a session capability for every clients and clients loggin to session with password and username.

Does converter works for every clients well?
Thanks;