Question

MSDN points out that mutating access to the .NET Dictionary<K,V> type is not thread safe. Is there a standard thread safe version?

Note: “No there is not” is a valid answer if it is true. In that cases (and it seem to be) I’ll go off and do the lock thing.

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Almost Duplicate

What’s the best way of implementing a thread-safe Dictionary in .NET? (Not exact because I want a standard type, not something I implement my self)

Answer 1

There isn’t. Consider this code, where each method/property was thread safe

if (!SFdict.Contains(key))
{
   SFdict[key] = value;
}

athough each action could be threadsafe, the block of code has a race condition, b/c there are two method calls and two different critical sections. The only way to do it is by hand

lock(lck)
{
   if (!dict.Contains(key))
   {
      dict[key] = value;
   }
}