forkIO can trivially defeat bracket

Consider this program,

import Control.Concurrent
import Control.Exception

main = do
    putStrLn "forking"
    forkIO $ bracket (putStrLn "forked") (const $ putStrLn "finalize") (const $ putStrLn "hello" >> threadDelay 100000000)
    threadDelay 10000
    putStrLn "done" 

Would you predict that it would print finalize?

Answer: no. It will print,

forking
forked
hello
done

It would pointed out by an author of a cryptographic library (raaz) that this is quite bad as it means that secure memory could leak out uncleared.

It's not entirely clear how best to deal with this. Perhaps raise a ThreadKilled async exception to all running threads during RTS shutdown, followed by a synchronization?

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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