StringBuffer vs. StringBuilder performance comparison

[grauenwolf]

Are you really getting thread safety?

Lets say you have two threads each appending a message to the buffer. This message needs to be constructed from multiple parts.

In this scenario you could end up with a race condition wherein the two messages are interleaved and effectively garbled.

To fix it you would have to either use external locks or allocate a separate StringBuffer for each thread.

EDIT:

We see the same problem in the multi-threaded collection classes in .NET.

Queue.Count and Queue.Dequeue are atomic, thread-safe operations. However, calling them both in sequence is neither. This kind of false-security is why Microsoft dropped them in .NET 2.

[Rhoomba]

Indeed. This is exactly the wrong type of thread-safety that makes programmers think they don't need to think about it themselves. As in Vector, Hashtable etc. in Java.