这个C＃类/方法线程安全和并发访问安全吗？

Question

In the code below, is attachments object thread-safe? If calling code make changes to the attachments object while application running multiple threads, what may happen?

Thanks.

public static class Util {
    public static int AddMessage(string message, IEnumerable<FileAttachment> attachments, Dictionary<int, object> customFieldValues = null, int? assigneeUserId = null) {
        foreach (FileAttachment current2 in attachments) {
            //do something
        }
    }
}

Answer 1

In the code below, is attachments object thread-safe? And if calling code make changes to the attachments object while application running multiple threads, what may happen?

There is nothing that suggests that attachments is thread safe here. If other threads have access to those instances, and change the properties within those objects, bad things could happen.

A simple example - if the actual enumerable happens to be a List<T> , and another thread adds or removes an attachment, the foreach loop will throw as it enumerates due to the underlying collection changing...