Is concurrency hard?

[Richard A. O'Keefe]

Joe Armstrong (AL/EAB)" <joe.armstrong@REDACTED> wrote:
	Now in physics there is no concept of sharing and no concept of
	simultaneity at a distance.  We can only say that two things
	occur at the same time if they occur at the same place.
	
Actually, in physics, there _is_ a notion of a 'timelike slice'.

But it has long seemed to me that mutable variables are basically a
device for providing instantaneous communication between remote parts of
a program, so there has to be something wrong with them.

The plain fact of the matter is that *programming* is hard.
Some languages make some things harder to program than others.

I remember reading a book about JSP years ago, which said that it
was basically a way of letting you simulate a collection of millions
of concurrent objects by inverting their code, and I wondered at the
time "why not just use a programming language that lets you have
millions of concurrent objects"?  (The target language was in fact COBOL.)