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Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC

Commits:

306120d2

by Duncan Coutts at 2026-07-24T18:05:43-04:00

Fix flaky test T3994 on FreeBSD

On current FreeBSD versions, calling getpgid on a zombie process fails.
In T3994, if we're really unlucky with delays and scheduling then we can
end up in exactly that situation.

Just catch that specific exception and ignore it. It's rare, and not our
fault.

1 changed file:

testsuite/tests/process/T3994.hs

Changes:

testsuite/tests/process/T3994.hs

  module Main where
  import Control.Concurrent
 +import Control.Exception
 +import Control.Monad
  import System.IO
 +import System.IO.Error
  import System.Process
  main :: IO ()
@@ -9,14 +12,24 @@ main = do (_,Just hout,_,p) <- createProcess (proc "./T3994app" ["start", "10000
                              { std_out = CreatePipe, create_group = True }
            start <- hGetLine hout
            putStrLn start
 -          interruptProcessGroupOf p
 -          t <- myThreadId
 -               -- timeout
 -          forkIO $ do
 -            threadDelay 5000000
 -            putStrLn "Interrupting a Running Process Failed"
 -            hFlush stdout
 -            killThread t
 -          waitForProcess p
++
 +          -- On FreeBSD if we're _really_ unlucky with scheduling, then the
 +          -- call to interruptProcessGroupOf can fail due to the process
 +          -- having already terminated (despite it running for at least 10ms!)
 +          -- If so, we just skip doing anything rather than fail the test,
 +          -- since this isn't our fault and is rare and scheduling dependent.
 +          -- See #27512 and https://reviews.freebsd.org/D58393
 +          handleJust (guard . isDoesNotExistError) (\_ -> return ()) $ do
 +            interruptProcessGroupOf p
 +            t <- myThreadId
 +                 -- timeout
 +            forkIO $ do
 +              threadDelay 5000000
 +              putStrLn "Interrupting a Running Process Failed"
 +              hFlush stdout
 +              killThread t
 +            waitForProcess p
 +            return ()
++
            putStrLn "end"
            return ()