On Wed, Aug 25, 2010 at 9:56 AM, Matthew Flatt <mfl...@cs.utah.edu> wrote: > At Wed, 25 Aug 2010 09:42:40 -0400, Sam Tobin-Hochstadt wrote: >> While trying to use futures to parallelize a simple piece of code, I >> was able to remove all of the waiting except for this: >> >> future: 3 waiting for runtime at 1282743524205.783936: [scheme_make_envunbox] >> >> which happens continuously. What causes this function to be invoked, >> and how can I eliminate it? > > It happens when initializing a local variable that is assigned via > `set!'. Probably we should inline scheme_make_envunbox() in > JIT-generated code.
Ok, that's kind of surprising. It seems that Typed Racket's optimizer is transforming the program in such a way that the bytecode compiler inserts `set!' where it wasn't before. I've attached the relevant file (which is just TR applied to the mandlebrot example from the futures paper). When the #:optimize keyword is used, the futures wait on `scheme_make_envunbox'. When it isn't used, there's much less waiting (just allocation and jitting). Unfortunately, trying to decompile this file produces an error in the decompiler: [sa...@punge:~/tmp plt] raco decompile mandelbrot.rkt hash-ref: no value found for key: 1128 so it's hard to tell exactly what's happening. -- sam th sa...@ccs.neu.edu
mandelbrot.rkt
Description: Binary data
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