CODEWITHSUNDEEP
c#multithreadingsocketsudpudpclient
raz
raz

Reputation: 29

Trying to multithread using a global udpclient object, is there possible collisions issues?

I'm making a project in a p2p sharing system which will initiate a lot of sockets with the same ports. right now I'm using a global UdpClient which will use receive and sendasync methods on different threads with different endpoints. there is no usage of mutex as of now which is why I'm asking if collisions are possible using said object if I'm not changing the information inside this object

right now I tried only one example and it doesn't seem to collide although I don't trust one example enough for a full answer

Upvotes: 0

Views: 145

Answers (1)

JonasH
JonasH

Reputation: 36629

As far as I can see, UdpClient is not thread safe. Thread safe objects should specifically mention that in the documentation, and UdpClient does not seem to do that.

So without any type of synchronization your code is most likely not safe. Testing is not sufficient since multi threading bugs are notorious for being difficult to reproduce. When you write multi threaded code you need to ensure any shared data is synchronized appropriately.

Using it within a lock is probably safe. But that is not a guarantee, UI objects are only safe to use from the thread that created the. Unfortunately that is not always well documented. A problem with locks is that it will block the thread, so locks are best used for very short and fast sections of code, not while doing long running operations like IO. And I don't think the compiler will even let you hold a lock while awaiting.

Another pattern is to use one or more concurrent queues, i.e. threads put messages on the queue, and another thread reads from the queue and sends the messages. There are many possible designs, and the best design will really depend on the specific application. However, designing concurrent systems is difficult, and I would recommend trying to create modules that are fairly independent, so you can understand and test a single module, without having to understand the entire program.

Memory is safe read concurrently. But the same does not extend to objects, since many object may mutate internal state when reading. Some types, like List<T>, specifically mentions that concurrent reads are safe. So make sure you check the documentation before using any object concurrently.

Upvotes: 0

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