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5528 :: Advice on how to handle: "global using GC'ed memory"

• treeform (orginal) [2019-11-15T19:07:11+01:00] view original

  So I been using async stuff and a global connections seq for a while in production and stuff. I don't have any issues with this, but it appears to cause a warning.

  What can I do about it? Should I silence the warning? What kind of issues should I expect? Under my impressions is that async stuff should all be using the same thread so sharing things like seq should be fine?

  Is there a better way to write this code?

  
  nim-1.0.0/lib/pure/asyncmacro.nim(271, 31) Warning: 'cbIter' is not GC-safe as it accesses 'connections' which is a global using GC'ed memory [GcUnsafe2]
  Run

  https://github.com/treeform/ws/blob/master/tests/chat.nim#L3

  This prompted the question: https://github.com/treeform/ws/issues/9

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• Araq (orginal) [2019-11-15T22:54:55+01:00] view original

  Try to compile with --threads:on to turn this warning into an error. Your code is not threadsafe. The following variant should work:

  var connections {.threadvar.}: seq[WebSocket] # no explicit init here, but the default of @[] works fine
  
  Run

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• kodkuce (orginal) [2019-11-15T23:39:59+01:00] view original

  yep i have same issue, from what i see you put those vars as thredvars and then change them with procs... my issue is i dont get why this is needed, i thinked async works whitout -threads:on? Will that new arcgc solve this pain?

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• mratsim (orginal) [2019-11-16T09:09:32+01:00] view original

  Yes you can ignore those warnings when you don't have threads on. They may have be put in place for future compat with the threadpool module.

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