Warning about fork vs resourceForkIO

2012-11-07 14:35:31 +02:00 · 2012-11-07 14:35:31 +02:00 · a144b56928
commit a144b56928
parent ed5e65ae95
1 changed files with 4 additions and 0 deletions
--- a/yesod-core/Yesod/Handler.hs
+++ b/yesod-core/Yesod/Handler.hs
@ -1034,6 +1034,10 @@ instance MonadIO (GHandler sub master) where
    liftIO = GHandler . const . lift
 instance MonadBase IO (GHandler sub master) where
    liftBase = GHandler . const . lift
+-- | Note: although we provide a @MonadBaseControl@ instance, @lifted-base@'s
+-- @fork@ function is incompatible with the underlying @ResourceT@ system.
+-- Instead, if you must fork a separate thread, you should use
+-- @resourceForkIO@.
 instance MonadBaseControl IO (GHandler sub master) where
    data StM (GHandler sub master) a = StH (StM (ResourceT IO) a)
    liftBaseWith f = GHandler $ \reader ->