Re: The D Programming Language
Andrei Alexandrescu (See Website For Email) wrote:
James Kanze wrote:
Andrei Alexandrescu (See Website For Email) wrote:
That's simply wrong. Java does not check thread safety
statically, yet is able to define behavior of even incorrect
multithreaded code.
Writing to a double while another thread is reading it is
undefined behavior in Java.
I've ran a number of searches for that ("java undefined behavior
double", "java undefined behavior threads double" etc.), no avail. I'd
be glad if you provided a reference. Thanks!
Maybe (also) we're using slightly different definitions for undefined
behavior?
I am still waiting for a response on this issue, or a retraction of the
initial statement.
This is relevant to C++ in the following way. When the C++ thread
standardization process started, it was assumed that the Java memory
model ensures well-defined programs even when they do have races. The
committee decided (correctly IMHO) to depart from that model for
efficiency reasons, leaving the behavior of certain programs undefined.
My current understanding is that races on longs and doubles could
produce undefined longs and doubles being read, but not undefined programs.
Now, if Java does allow programs with undefined behavior, that would
quite change the "golden standards" in terms of safety.
Andrei
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