id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
2884,Compiled code performance worsens when module names are long enough,jcpetruzza,igloo,"Attached to this report is an example where by simply renaming a module, performance degrades 2.5 times.

{{{
#diff long-modname-ver.hs short-modname-ver.hs
2c2
< import VeryLongModuleName
---
> import ShortM

#diff VeryLongModuleName.hs ShortM.hs
1c1
< module VeryLongModuleName
---
> module ShortM

#ghc --make -O2 -Wall long-modname-ver.hs

#ghc --make -O2 -Wall short-modname-ver.hs

#time -p ./long-modname-ver > /dev/null
real 55.90
user 55.17
sys 0.51

#time -p ./short-modname-ver > /dev/null
real 22.23
user 21.97
sys 0.10
}}}

According to some measures by dons, the threshold seems to be at module length 10 (see attached graph).

Some further disussion on this thread [http://thread.gmane.org/gmane.comp.lang.haskell.glasgow.user/16037].",bug,closed,normal,6.12 branch,Compiler,6.10.1,fixed,,bos@…,Unknown/Multiple,Unknown/Multiple,Runtime performance bug,Unknown,,,,