This is very helpful, thank you. In fact, my "naive" version (in untyped Racket) was about the same speed as my colleague's naive Python version. Switching to fl+, fl-, etc bought me a 10x improvement (I presume from the JIT compiler avoiding boxing and unboxing?). Annoyingly, my colleague had got the same speedup by using Numpy, but that does require a change to the way one arranges the calculation (and the change is unnatural, to my eye).
Simply switching to Racket on Chez improved the naive version by a factor of 5x, which was very nice to see. However, I'm now unsure how to continue. How should I think about making speed improvements? There are flvectors, for example: under what circumstances would these help? Should I expect more gains from TR above this, or do the gains only come from TR figuring out that it can use fl+ rather than me doing so? Many thanks again, James > On 5 Jun 2019, at 17:08, Philip McGrath <phi...@philipmcgrath.com> wrote: > > In case it's helpful as a workaround, changing the #lang line to: > #lang typed/racket #:no-optimize > will disable the type-based optimizations, so the problematic > `unsafe-make-flrectangular` isn't introduced and the segfault is avoided. You > presumably loose some performance, though, and "use this flag to work around > a compiler bug" may not be the first example you want to show your > colleagues—but, even without the type-based optimizations, Racket is probably > still faster than Python. > > In case it's helpful for your colleagues, someone recently brought up this > direct comparison of speed benchmarks for Racket and Python 3: > https://benchmarksgame-team.pages.debian.net/benchmarksgame/fastest/racket-python3.html > > -Philip > > > On Wed, Jun 5, 2019 at 11:46 AM Matthew Flatt <mfl...@cs.utah.edu> wrote: > I had just reached the same conclusion. Specifically, it looks like a > missing runstack sync in the JIT-inlined `unsafe-make-flrectangular`. > > Thanks! > > At Wed, 5 Jun 2019 11:40:41 -0400, Sam Tobin-Hochstadt wrote: > > I think this is a miscompilation of `unsafe-make-flrectangular` by the > > underlying Racket compiler. > > The below program is a plain racket version of the code, with just one > > use of unsafe, a call to `unsafe-make-flrectangular`. If that's > > replaced with `make-flrectangular`, then the program works propetly. > > Furthermore, if we add a print statement that requires the argument to > > `unsafe-make-flrectangular`, then the program also works correctly. > > The program also works correctly with the JIT off, and under RacketCS. > > https://gist.github.com/samth/683042c4754c1c5ce284794b19dd37e3 > > > > On Wed, Jun 5, 2019 at 11:02 AM 'Paulo Matos' via Racket Users > > <racket-users@googlegroups.com> wrote: > > > > > > > > > On 05/06/2019 16:47, Philip McGrath wrote: > > > > What version of Racket are you using? I get a segfault in 7.2, but 7.3 > > > > works for me. > > > > > > I see the segfault in 7.1 but not in 7.2 or 7.3. Then I run it under > > > valgrind and I see it in all the versions. :) > > > It's there, but sometimes hiding. > > > > > > Will take a look. > > > > > > > -Philip > > > > > > > > > > > > On Wed, Jun 5, 2019 at 10:42 AM James Geddes <james.ged...@gmail.com > > > > <mailto:james.ged...@gmail.com>> wrote: > > > > > > > > Dear All, > > > > > > > > The following Typed Racket program is intended to produce an image > > > > of the Mandelbrot set (but it doesn't bother actually displaying the > > > > image). > > > > > > > > Running the program using command-line Racket causes a crash. > > > > Specifically, Racket terminates with the error message: > > > > > > > > Segmentation fault: 11 > > > > > > > > However, > > > > > > > > 1. The program runs successfully in DrRacket; > > > > > > > > 2. Reducing the size of the image to, say, 200 x 200 (by changing > > > > the last arguments in the calls to `make-ticks`) also results in > > > > successful termination, without a segmentation fault. > > > > > > > > Any advice appreciated! > > > > > > > > (PS: I'm not actually that interested in making pictures. I'm trying > > > > to do some speed benchmarks to show my colleagues, particularly > > > > those who argue that Python is faster, and this example happened to > > > > be on hand.) > > > > > > > > > > > > James > > > > > > > > > > > > > > > > > > > > #lang typed/racket > > > > > > > > ;; Generate an image of the Mandelbrot set > > > > (https://en.wikipedia.org/wiki/Mandelbrot_set) > > > > > > > > (define *iteration-limit* : Integer 50) > > > > > > > > (: mandel (-> Float-Complex Integer)) > > > > ;; Given c, iterate z <- z^2 + c starting from z = 0 until either > > > > |z| > 2 or the number of iterations > > > > ;; exceeds *iteration-limit*. Returns the number of iterations > > required. > > > > (define (mandel c) > > > > (let mandel-iter ([z 0.0+0.0i] > > > > [i 0]) > > > > (if (or (>= i *iteration-limit*) (> (magnitude z) 2.0)) > > > > i > > > > (mandel-iter (+ c (sqr z)) (+ i 1))))) > > > > > > > > (: brot ((Listof Float) (Listof Float) -> (Listof Integer))) > > > > ;; Apply mandel to a rectangular grid of complex numbers > > > > (define (brot xs ys) > > > > (for*/list : [Listof Integer] > > > > ([y (in-list ys)] > > > > [x (in-list xs)]) > > > > (mandel (make-rectangular x y)))) > > > > > > > > (: make-ticks (-> Float Float Integer (Listof Float))) > > > > (define (make-ticks min max resolution) > > > > (range min max (/ (- max min) resolution))) > > > > > > > > (define *xs* (make-ticks -1.5 0.5 300)) > > > > (define *ys* (make-ticks -1.0 1.0 300)) > > > > > > > > ;; Compute a Mandelbrot image (but then discard it) > > > > (void (brot *xs* *ys*)) > > > > > > > > > > > > > > > > > > > > -- > > > > You received this message because you are subscribed to the Google > > > > Groups "Racket Users" group. > > > > To unsubscribe from this group and stop receiving emails from it, > > > > send an email to racket-users+unsubscr...@googlegroups.com > > > > <mailto:racket-users%2bunsubscr...@googlegroups.com>. > > > > To view this discussion on the web visit > > > > > > https://groups.google.com/d/msgid/racket-users/194F0EE9-0B9E-412B-A2C0-BCE51CD0 > > AA75%40gmail.com. > > > > For more options, visit https://groups.google.com/d/optout. > > > > > > > > -- > > > > You received this message because you are subscribed to the Google > > > > Groups "Racket Users" group. > > > > To unsubscribe from this group and stop receiving emails from it, send > > > > an email to racket-users+unsubscr...@googlegroups.com > > > > <mailto:racket-users+unsubscr...@googlegroups.com>. > > > > To view this discussion on the web visit > > > > > > https://groups.google.com/d/msgid/racket-users/CAH3z3gY4Cte5p0ZuY6yCmjAc1jjebZQ > > 6GTaQQZJXQxdoqaop2Q%40mail.gmail.com > > > > > > <https://groups.google.com/d/msgid/racket-users/CAH3z3gY4Cte5p0ZuY6yCmjAc1jjebZ > > Q6GTaQQZJXQxdoqaop2Q%40mail.gmail.com?utm_medium=email&utm_source=footer>. > > > > For more options, visit https://groups.google.com/d/optout. > > > > > > -- > > > Paulo Matos > > > > > > -- > > > You received this message because you are subscribed to the Google Groups > > "Racket Users" group. > > > To unsubscribe from this group and stop receiving emails from it, send an > > email to racket-users+unsubscr...@googlegroups.com. > > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/racket-users/cea3ba1c-64fe-2d39-a8ed-98570751 > > fb3e%40linki.tools. > > > For more options, visit https://groups.google.com/d/optout. > > > > -- > > You received this message because you are subscribed to the Google Groups > > "Racket Users" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to racket-users+unsubscr...@googlegroups.com. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/racket-users/CAK%3DHD%2BaX%2Bh4%3DEAOt4qYC8dB > > 8JfPCRUfHvo0C8C-BnbzAfdfuqw%40mail.gmail.com. > > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-users/5cf7e3b9.1c69fb81.74606.c239SMTPIN_ADDED_MISSING%40gmr-mx.google.com. > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-users/CAH3z3gb1hoEKSU4ygZLghPZN%3Daz3J5MANZAJzxA6i2X9dM3ztg%40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. 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