Question

I am facing this issue:
I have lots of threads (1024) who access one large collection – Vector.
Question:
is it possible to do something about it which would allow me to do concurrent actions on it without having to synchronize everything (since that takes time)? What I mean, is something like Mysql database works, you don’t have to worry about synchronizing and thread-safe issues. Is there some collection alike that in Java? Thanks

Answer 1

Vector is a very old Java class – predates the Collections API. It synchronizes on every operation, so you’re not going to have any luck trying to speed it up.
You should consider reworking your code to use something like ConcurrentHashMap or a LinkedBlockingQueue, which are highly optimized for concurrent access.

Failing that, you mention that you’d like performance and access semantics similar to a database – why not use a dedicated database or a message queue? They are likely to implement it better than you ever will, and it’s less code for you to write!

[edit] Given your comment:

all what thread does is adding elements to vector 
(only if num of elements in vector = 0) & 
removing elements from vector. (if vector size > 0)

it sounds very much like you should be using something much more like a queue than a list! A bounded queue with size 1 will give you these semantics – although I’d question why you can’t add elements if there is already something there. When you’ve got thousands of threads this seems like a very inefficient design.