In Honor of Per Brinch Hansen (1938-2007)

Prof. Per Brinch Hansen passed away in July.

Let's raise a toast to Prof. Hansen's life, his manifold contributions to computer science and the many delightful essays on concurrency .

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plenty of interesting stuff to read here...


The look back upon Concurrent Pascal and Monitors was an interesting read; I thought this quote was interesting - are there any languages following closely in these footsteps? I haven't thought through / don't know enough of the implications in e.g. Erlang or Occam-pi. Seems like references to channels are allowed (depending on how you define that), whereas polling the same channel(s) doesn't seem so commonly allowed e.g. I don't know Erlang but I don't think you can do that since actors only have their own mailbox? (Oh, and, er, um, Erlang isn't about synchronous communication tra la.)

After Concurrent Pascal I developed two smaller languages. Each of them
was again designed to explore a single programming concept: conditional
critical regions in Edison, and synchronous communication in Joyce (Brinch
Hansen 1981, 1989a).
There are exactly three ad hoc restrictions in Joyce:

  • A process cannot access global variables.
  • A message cannot include a channel reference.
  • Two processes cannot communicate by polling the same channel(s).

I think only the first one is really necessary.


I don’t think we have found the right programming concepts for parallel computers yet. When we do, they will almost certainly be very different from anything we know today.

said in 1993. has that been resolved?


great (thought provoking, or just historically funny?) comments by some of the reviewers like

I have a deep respect for the monitor concept: in my opinion it is better than message passing, which is what we are stuck with.

Sad news

I just found out that PBH died LAST JULY!! I think he was a largely unsung hero of computer science and should have been awarded the Turing Award. His books are a model of crystal clear writing that budding CS authors should study and learn from.