[GHC] #8591: Concurrent executions of ghc-pkg can cause inconstant package.cache files

[GHC]

#8591: Concurrent executions of ghc-pkg can cause inconstant package.cache files
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              Reporter:  janm        |            Owner:  pgj
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Package     |          Version:  7.6.3
  system                             |         Keywords:  ghc-pkg race
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:  FreeBSD     |       Difficulty:  Unknown
       Type of failure:  Other       |       Blocked By:
             Test Case:              |  Related Tickets:
              Blocking:              |
Differential Revisions:              |
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Comment (by pgj):

 Replying to [comment:2 janm]:
 > A better approach would be for the process to open the targetFile with
 O_EXCL (and create it with O_CREAT if it doesn't exist), and hold it open
 while doing the atomic rename on top of the target. That way the
 targetFile is used a lock to synchronise updates between concurrent
 processes.

 Does the same problem persist with GHC 7.8.x?  Unfortunately, I do not own
 such a beefy hardware, although I may be able to get some help in that
 respect from the FreeBSD Project.  What is the version of the operating
 system (that is, ideally {{{OSVERSION}}})?  I guess the architecture is
 {{{amd64}}}.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8591#comment:4>
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