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2516 :: Recreating threads?

• shaunc (orginal) [2016-09-05T16:30:14+02:00] view original

  I have code in the following general form:

  while ...:
      createThread(...)
      ...
      joinThreads(...)
  Run

  It works the first iteration, but the threads don't seem to start on the 2nd iteration. Is there any reason/workaround for this?

  One obvious workaround would be to make the threads global, so they only have to be started once. However, the general structure of the program is something like

  
  A
  B
  C
  A
  B
  C
  ...
  Run

  where threads will be doing something different in A, B and C -- so having to have all threads global requires a good bit more complexity.

  EDIT

  One answer would be to use spawn and not createThread. But I am using channels, and http://forum.nim-lang.org/t/959 recommends using createThread in this case. I have threads of different types doing different tasks (and talking with each other) -- so unless it were possible to partition the thread pool, it would seem that I need more control than "spawn" provides.

  (NB -- this all fits into a "bulk synchronous parallel" architecture with multiple reduce steps -- I'm sure there is a higher-level library that would help here. :))

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• shaunc (orginal) [2016-09-06T17:10:03+02:00] view original

  BTW -- one workaround I have found: variables of type Thread (it seems) can't be reused, but they can be local. So

  while  ...:
    proc foo() =
      createThread(...)
      ...
      joinThread(...)
    foo()
  Run

  will work.

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• Araq (orginal) [2016-09-08T09:04:43+02:00] view original

  • As far as I know with devel the spawn should work much better with channels than it used to.
  • The createThread problem is a known issue that needs to be fixed, but in general threads+channels are designed to be used as global variables... We need a light-weight option for these too. I know people use allocShared for channels and stuff but this needs to be supported out of the box.

  As always, PRs are welcome.

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