[GHC] #1010: ghci crashes when running out of heap.

[GHC]

#1010: ghci crashes when running out of heap.
-----------------------------------+----------------------------------------
    Reporter:  tullsen at galois.com  |       Owner:         
        Type:  bug                 |      Status:  new    
    Priority:  normal              |   Milestone:         
   Component:  Compiler            |     Version:  6.6    
    Severity:  normal              |    Keywords:         
  Difficulty:  Unknown             |    Testcase:         
Architecture:  x86                 |          Os:  MacOS X
-----------------------------------+----------------------------------------
This may be the same as ticket:1004, but the program is smaller (just
 running out of heap)
 and there's some more data points.

 Running compiled code works fine (i.e., exits cleanly):
 {{{
 $ ghc -O2 Main.hs
 $ ./a.out +RTS -M3M
 Heap exhausted;
 Current maximum heap size is 2998272 bytes (2 Mb);
 use `+RTS -M<size>' to increase it.
 }}}
 running fully compiled code from ghci also exits cleanly:
 {{{
 $ ghci Main.hs +RTS -M5M
    ___         ___ _
   / _ \ /\  /\/ __(_)
  / /_\// /_/ / /  | |      GHC Interactive, version 6.6, for Haskell 98.
 / /_\\/ __  / /___| |      http://www.haskell.org/ghc/
 \____/\/ /_/\____/|_|      Type :? for help.

 Loading package base ... linking ... done.
 Ok, modules loaded: Main.
 Prelude Main> main
 Heap exhausted;
 Current maximum heap size is 4997120 bytes (4 Mb);
 use `+RTS -M<size>' to increase it.
 }}}
 but invoking compiled code from ghci gives various infelicitious results:
 {{{
 $ ghci Main.hs +RTS -M5M
    ___         ___ _
   / _ \ /\  /\/ __(_)
  / /_\// /_/ / /  | |      GHC Interactive, version 6.6, for Haskell 98.
 / /_\\/ __  / /___| |      http://www.haskell.org/ghc/
 \____/\/ /_/\____/|_|      Type :? for help.

 Loading package base ... linking ... done.
 Ok, modules loaded: Main.
 Prelude Main> test 1000000
 <interactive>: internal error: scavenge_mark_stack: unimplemented/strange
 closure type 3660 @ 0x1b1f0a4
     (GHC version 6.6 for i386_apple_darwin)
     Please report this as a GHC bug:
 http://www.haskell.org/ghc/reportabug

 $ ghci Main.hs +RTS -M5M
    ___         ___ _
   / _ \ /\  /\/ __(_)
  / /_\// /_/ / /  | |      GHC Interactive, version 6.6, for Haskell 98.
 / /_\\/ __  / /___| |      http://www.haskell.org/ghc/
 \____/\/ /_/\____/|_|      Type :? for help.

 Loading package base ... linking ... done.
 Ok, modules loaded: Main.
 Prelude Main> test 1000000
 <interactive>: internal error: stg_ap_p_ret
     (GHC version 6.6 for i386_apple_darwin)
     Please report this as a GHC bug:
 http://www.haskell.org/ghc/reportabug


 $ ghci Main.hs +RTS -M3M
    ___         ___ _
   / _ \ /\  /\/ __(_)
  / /_\// /_/ / /  | |      GHC Interactive, version 6.6, for Haskell 98.
 / /_\\/ __  / /___| |      http://www.haskell.org/ghc/
 \____/\/ /_/\____/|_|      Type :? for help.

 Loading package base ... linking ... done.
 Ok, modules loaded: Main.
 Prelude Main> test 100000
 Illegal instruction


 $ ghci Main.hs +RTS -M4M
    ___         ___ _
   / _ \ /\  /\/ __(_)
  / /_\// /_/ / /  | |      GHC Interactive, version 6.6, for Haskell 98.
 / /_\\/ __  / /___| |      http://www.haskell.org/ghc/
 \____/\/ /_/\____/|_|      Type :? for help.

 Loading package base ... linking ... done.
 Ok, modules loaded: Main.
 Prelude Main> test 1000000
  Bus error
 }}}
 I think you get the idea.

 The program is this:
 {{{
 module Main where

 break2 p (x:xs) = if p x then
                     ([],x:xs)
                   else
                     let (b1,b2) = break2 p xs
                     in  (x : b1, b2)
 break2 p []     = ([],[])

 surprise xs = b1 ++ "\n surprise " ++ b2
                where
                (b1,b2) = break2 (=='\n') xs

 test n = length $ surprise $ [head (show i) | i <-[1..n] ] ++ "\n the end"

 main = print $ test 1000000
 }}}

 As an aside: I expected this program to run in constant space.  AFAIK GHC
 evaluates "THUNK_SELECTORS" and
 thus eliminates the space leak in this infamous example
 [Hughes83][Wadler87][Sparud93] etc, but clearly this program is leaky!

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1010>
GHC <http://www.haskell.org/ghc/>
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