2 threads increasing a static integer

Question

if i am increasing a static by 2 different Tasks or Threads do i need to lock it? i have this class which will be used by multiple threads at the same time, it returns a proxy to be used inside a thread but i dont want to use the same proxy at the same time with each thread, so i thought incrementing a static integer is the best way, any suggestions? ``` class ProxyManager { //static variabl gets increased every Time GetProxy() gets called private static int Selectionindex; //list of proxies public static readonly string[] proxies = {}; //returns a web proxy public static WebProxy GetProxy() { Selectionindex = Selectionindex < proxies.Count()?Selectionindex++:0; return new WebProxy(proxies[Selectionindex]) { Credentials = new NetworkCredential("xxx", "xxx") }; } } ``` based on the selected answer ``` if(Interlocked.Read(ref Selectionindex) < proxies.Count()) { Interlocked.Increment(ref Selectionindex); } else { Interlocked.Exchange(ref Selectionindex, 0); } Selectionindex = Interlocke…

Accepted Answer

If you increment a static variable across threads you will end up with inconsistent results. Instead use Interlocked.Increment:

```
private void IncrementSelectionIndex() {
    Interlocked.Increment(ref Selectionindex);
}
```

64-bit reads are atomic, but to fully support 32-bit systems you should use Interlocked.Read

```
private void RetrieveSelectionIndex() {
    Interlocked.Read(ref Selectionindex);
}
```

2 threads increasing a static integer

Solution

Problem