Is += an atomic operation in C#?

Question

I'm developing a data aggregation object on a multi-thread environment, and I have the following situation:

int counts;

// This event is triggered by many threads at the same time
public void OnDataReceived(DataEvent evt)
{
   counts += evt.counts;
}

My question is whether it is safe to do

counts += evt.counts;

or I need something like

lock(lockObject)
{
   counts += evt.counts;
}

+= is *not* an atomic operation. You should use Interlocked.Increment. — mm8, May 02 '19 at 15:12
Nope. By the way, whether a particular operation in .NET is guaranteed to be atomic does not only depend on the operation itself, but also on the data type it is applied to... — , May 02 '19 at 15:13

score 1 · Accepted Answer · answered May 02 '19 at 15:14

1

+= is not an atomic operation. You should use the Interlocked.Increment method.

answered May 02 '19 at 15:14

mm8

1 Answers1