id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
4850,Segfault when lots of blocked MVar messages,NeilMitchell,,"I reduced the original problem I started with in #4835 to the following example, which spans 3 files. There is still further scope for reducing the test case - I have stopped now it's standalone without any data file or package dependencies. I have reproduced this bug on GHC 7.0.2-rc1.

The program does has some parallelism, and due to a bug in the parallel-io library (since fixed) it causes lots of MVar blocked messages. This program sometimes runs to completion, sometimes gives a blocked MVar, and sometimes segfaults. I see the segfault > 50% of the time.

The program is compiled and run with:

{{{
ghc --make Main.hs -threaded && Main.exe
}}}

Line 82 of {{{Main.hs}}} does {{{getDirectoryContents ""C:/Windows""}}}. It seems to crash if I put file or directory operations here, but not if I put sleep or pure computation there. This line can be changed to any reasonably sized directory to get the same effects - there is nothing specific to that folder.",bug,closed,high,7.0.2,Runtime System,7.0.1,fixed,,,Windows,Unknown/Multiple,Runtime crash,,,,,