[Hugs] #79: Memory leak ?

[Hugs]

#79: Memory leak ?
--------------------+-------------------------------------------------------
 Reporter:  guest   |       Owner:  nobody
     Type:  defect  |      Status:  new   
 Priority:  major   |   Milestone:        
Component:  hugs    |     Version:  200609
 Keywords:          |  
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 Lately I've come across a most interesting error. With this code for rev:
 {{{
 rev []  xs = xs
 rev (x:xs) ys = rev xs (x:ys)
 }}}
 Hugs returned:

 {{{
 Main> rev tab1 []

 ERROR - Garbage collection fails to reclaim sufficient space
 Main>
 }}}



 After some tests I've found out that (of course after restarting Hugs)
 that request to print on screen ''tab''  where the code is

 {{{
 tab = [1..1000000]
 }}}

 will result in a same crash (ERROR - Garbage collection fails to reclaim
 sufficient space). Results where like this:[[BR]]


 {{{
 .
 .
 .
 246368,246369,246370,246371,246372,246373,246374,246375,246376,246377,246378,246379,246380,246381,246382,246383,246384,246385,246386,246387,246388,246389,246390,246391,246392,246393,246394,246395,246396,246397,246398,246399,246400,246401,246402,246403,246404,246405,246406,246407,246408,246409,246410
 ERROR - Garbage collection fails to reclaim sufficient space
 Main>
 }}}


 Yet still request to simply print [1..1000000] is managed without this
 problem (of course after restarting Hugs). Seems like some sort of a
 memory leak, but in which part? After those problems occure there are
 problems to do much simpler thing. Example:[[BR]]


 {{{
 Main> (length tab) `seq` ""
 "
 ERROR - Garbage collection fails to reclaim sufficient space
 Main> [1..100]
 [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,
 ERROR - Garbage collection fails to reclaim sufficient space
 Main>
 }}}



 Looks like the constructor '..' works well because there is no problem
 with printing [1..n] where n > 1 000 000  but on the other hand there seem
 to be problems on passing such list (even shorter) to a variable
 ''tab''.[[BR]]

 1. Is this passing blocks garbage collector from cleaning this memory once
 it's aloccated during printing?[[BR]]

 2. Maybe it was intentional because of something I don't know. If it is,
 please could You explain why?
 [[BR]]

 Many thanks for Your time.[[BR]]

 Simon Laszczynski (bast_ian at poczta.onet.pl)

 [[BR]]
 PS: Forgive me my bad english.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hugs/ticket/79>
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