Reputation: 174

What is the best way to have synchronized a collection of objects between various threads in .Net?

I need to have a List or Dictionary accessed from different threads in a thread safe mode. With Adds, Removes, Foreachs, etc.

Upvotes: 1

Answers (5)

Dror Helper

Reputation: 30790

Basically it depends on the pattern you need to use. If you have several threads writing and reading the same place you can use the same data structure that you would have used with a single thread (hastable, array, etc.) with a lock/monitor or a ReaderWriterLock to prevent race conditions. In case you need to pass data between threads you'll need some kind of queue (synced or lockfree) that thread(s) of group A would insert to and thread(s) of group B would deque from. You might want to use WaitEvent (AutoReset or Manual) so that you won't loose CPU when the queue is empty. It really depends on what kind of workflow you want to achieve.

Upvotes: 1

Tom Carr

Reputation: 1439

Without knowing specifics, I'd lean towards delegates and events to notify of changes.

http://msdn.microsoft.com/en-us/library/17sde2xt(VS.71).aspx

And implementing the Observer or Publish Subscribe pattern

http://en.wikipedia.org/wiki/Observer_pattern http://msdn.microsoft.com/en-us/library/ms978603.aspx

Upvotes: 0

Thomee

Reputation: 4720

A number of the collection classes in .Net have built in support for synchronizing and making access from multiple threads safe. For example (in C++/CLR):


    Collections::Queue ^unsafe_queue = gcnew Collections::Queue();
    Collections::Queue ^safe_queue = Collections::Queue::Synchronized(unsafe_queue);

You can throw away the reference to unsafe_queue, and keep the reference to safe_queue. It can be shared between threads, and you're guaranteed thread safe access. Other collection classes, like ArrayList and Hashtable, also support this, in a similar manner.

Upvotes: 0