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8285 :: Stacktrace when using async with arc/orc is not helpful

• giaco (orginal) [2021-07-30T17:01:19+02:00] view original

  The stacktrace returned by an async program compiled with arc/orc is different than one compiled with refc. Most importantly, the stacktrace with arc/orc gives little help in finding out where the problem is.

  Example

  import std/[asyncdispatch]
  
  proc async4 {.async.} =
    debugEcho "async4"
    await sleepAsync(1000)
    raise newException(Exception, "Fooo")
  
  proc async3 {.async.} =
    debugEcho "async3"
    await sleepAsync(1000)
    await async4()
  
  proc async2 {.async.} =
    debugEcho "async2"
    await sleepAsync(1000)
    await async3()
  
  proc async1 {.async.} =
    debugEcho "async1"
    await sleepAsync(1000)
    await async2()
  
  proc firstTrampoline {.async.} =
    debugEcho "firstTrampoline"
    await async1()
  
  waitFor firstTrampoline()
  Run

  Output with arc/orc

  you can see that there's no hint that the problem happened in async4. The only info is the first async trampoline proc and the exception itself.

  
  firstTrampoline
  async1
  async2
  async3
  async4
  /home/arkanoid/nim/experiments/asyncexceptions.nim(27) asyncexceptions
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1937) waitFor
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390) read
  Error: unhandled exception: Fooo
  Async traceback:
    /home/arkanoid/nim/experiments/asyncexceptions.nim(27)                    asyncexceptions
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208)  processPendingCallbacks
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29)      firstTrampolineNimAsyncContinue
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145)     firstTrampolineIter
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390)   read
  Exception message: Fooo
   [Exception]
  Error: execution of an external program failed: '/home/arkanoid/nim/experiments/asyncexceptions '
  Run

  Output with refc

  
  firstTrampoline
  async1
  async2
  async3
  async4
  /home/arkanoid/nim/experiments/asyncexceptions.nim(27) asyncexceptions
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208) processPendingCallbacks
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29) async4NimAsyncContinue
  /home/arkanoid/nim/experiments/asyncexceptions.nim(6) async4Iter
  [[reraised from:
  /home/arkanoid/nim/experiments/asyncexceptions.nim(27) asyncexceptions
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208) processPendingCallbacks
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29) async3NimAsyncContinue
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145) async3Iter
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390) read
  ]]
  [[reraised from:
  /home/arkanoid/nim/experiments/asyncexceptions.nim(27) asyncexceptions
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208) processPendingCallbacks
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29) async2NimAsyncContinue
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145) async2Iter
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390) read
  ]]
  [[reraised from:
  /home/arkanoid/nim/experiments/asyncexceptions.nim(27) asyncexceptions
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208) processPendingCallbacks
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29) async1NimAsyncContinue
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145) async1Iter
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390) read
  ]]
  [[reraised from:
  /home/arkanoid/nim/experiments/asyncexceptions.nim(27) asyncexceptions
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208) processPendingCallbacks
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29) firstTrampolineNimAsyncContinue
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145) firstTrampolineIter
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390) read
  ]]
  [[reraised from:
  /home/arkanoid/nim/experiments/asyncexceptions.nim(27) asyncexceptions
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1937) waitFor
  /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390) read
  ]]
  Error: unhandled exception: Fooo
  Async traceback:
    /home/arkanoid/nim/experiments/asyncexceptions.nim(27)                    asyncexceptions
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208)  processPendingCallbacks
    /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29)      async4NimAsyncContinue
    /home/arkanoid/nim/experiments/asyncexceptions.nim(6)                     async4Iter
    #[
      /home/arkanoid/nim/experiments/asyncexceptions.nim(27)                    asyncexceptions
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208)  processPendingCallbacks
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29)      async3NimAsyncContinue
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145)     async3Iter
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390)   read
    ]#
    #[
      /home/arkanoid/nim/experiments/asyncexceptions.nim(27)                    asyncexceptions
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208)  processPendingCallbacks
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29)      async2NimAsyncContinue
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145)     async2Iter
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390)   read
    ]#
    #[
      /home/arkanoid/nim/experiments/asyncexceptions.nim(27)                    asyncexceptions
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208)  processPendingCallbacks
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29)      async1NimAsyncContinue
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145)     async1Iter
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390)   read
    ]#
    #[
      /home/arkanoid/nim/experiments/asyncexceptions.nim(27)                    asyncexceptions
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1935) waitFor
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1627) poll
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(1368) runOnce
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncdispatch.nim(208)  processPendingCallbacks
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(29)      firstTrampolineNimAsyncContinue
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncmacro.nim(145)     firstTrampolineIter
      /home/arkanoid/.choosenim/toolchains/nim-1.4.8/lib/pure/asyncfutures.nim(390)   read
    ]#
  Exception message: Fooo
   [Exception]
  Error: execution of an external program failed: '/home/arkanoid/nim/experiments/asyncexceptions '
  Run

  
  $ nim -v
  Nim Compiler Version 1.4.8 [Linux: amd64]
  Compiled at 2021-05-25
  Copyright (c) 2006-2021 by Andreas Rumpf
  
  git hash: 44e653a9314e1b8503f0fa4a8a34c3380b26fff3
  active boot switches: -d:release
  
  Run

  Is there anything I can do? I only see two options here:

  • don't use arc/orc
  • switch from async to threaded code

---

• Araq (orginal) [2021-07-30T17:38:20+02:00] view original

  Please report this on github, it's "only" a bug as far as I can tell.

---