[GHC] #8852: 7.8.1 uses a lot of memory when compiling attoparsec programs using <|>

[GHC]

#8852: 7.8.1 uses a lot of memory when compiling attoparsec programs using <|>
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        Reporter:  joelteon                      |            Owner:
            Type:  bug                           |           Status:  new
        Priority:  normal                        |        Milestone:
       Component:  Compiler                      |          Version:
      Resolution:                                |  7.8.1-rc2
Operating System:  Unknown/Multiple              |         Keywords:
 Type of failure:  Compile-time performance bug  |     Architecture:
       Test Case:                                |  Unknown/Multiple
        Blocking:                                |       Difficulty:
                                                 |  Unknown
                                                 |       Blocked By:
                                                 |  Related Tickets:
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Comment (by rezb1t):

 I'd like to note that this problem occurs when compiling darcs 2.8.4,
 happy, alex, network 2.5.0.0, and quite a few other libraries. Something
 is very wrong here, GHC either uses a tiny amount of RAM or it uses
 gigabytes.

 When compiling darcs, GHC used 4GB of RAM on one source file! Weirder yet,
 I've noticed that when used in tandem with cabal-install, the RAM isn't
 freed in between source files.. whether this is intended or not, I
 couldn't tell, but running ghc in make mode doesn't do this.

 The behavior is the same whether it be GHC 7.8.2 or HEAD of ghc-7.8
 currently

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8852#comment:2>
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