Is Array.Resize(..) threadsafe?

Question

Is calling Array.Resize on an array that is being used as a buffer for SAEA threadsafe? different threads all write to their own assigned part of the array, I just want to make the array bigger without locking once the initialized size runs out as connected users increase.

byte[] buffer; //Accessed
object expand_Lock = new object();

public void AsyncAccept()
{
    //Lock here so we don't resize the buffer twice at once
    lock(expand_Lock)
    {
        if (bufferFull)
        {
            Array.Resize(buffer, buffer.Length + 2048 * 100); //Add space for 100 more args
            //Is Array.Resize threadsafe if buffer can be read/wrote to at anytime?
            AssignMoreSAEA(2048, 100); //irrelevant to question what this does
        }
    }
}

Answer 1

No, Array.Resize is not thread-safe. The array that's being resized may have to be moved around in memory and the resized array will not even be the same array as the one passed in.

This means that one thread may be writing into the original array while Array.Resize is creating the new array and copying over items - the copy operation is not protected. This can result in loss of data.