Is Copying C# Events Before Null Checks Necessary for Thread Safety?

C#multi -threaded event processing: Best practice discussion

When dealing with the C#event in a multi -threaded environment, a common suggestion is to copy the event before checking whether the event is empty to avoid thread -related issues. However, some people question the necessity of this approach and believe that this is just a "superstition programming" model.

The reason for copying the incident

The purpose of copying events is to prevent potential air citation abnormalities when accessing events in a multi -threaded environment. It is assumed that if another thread cancels the event processing program when your thread is about to call the event, the event entrustment may quote the vacant reference.

However, as Eric Lippert pointed out, the event processing program itself is designed to cope with such potential problems. Therefore, the main focus should be to solve the situation that the incident may be empty.

The vacancy of the incident

"Standard Mode" using explicit empty values ​​is not the most effective way. As an alternative, a processing procedure for initialization events that will never be removed can be completely eliminated. This method only needs to add a simple operation to the event statement to ensure the avoidance problem of the vacancy without using cumbersome replication/inspection habits. C# 6 and the higher version of the precautions

In C# 6 and higher versions, the air merger computing ("?.") Provided a simple method of processing event calls. The following code effectively checks whether the event is empty, and only call it when the event is not empty:

Conclusion

Careful considerations to deal with events in multi -threaded environments. Although copying events can solve certain extreme situations, it is important to understand the inherent robustness of the event processing procedure and explore the alternative method. These methods can avoid the demand for air value inspection while maintaining thread security.

<code>SomeEvent?.Invoke(this, e);</code>

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