[GHC] #2028: STM slightly conservative on write-only transactions

[GHC]

#2028: STM slightly conservative on write-only transactions
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 Reporter:  JulesBean  |          Owner:         
     Type:  proposal   |         Status:  new    
 Priority:  normal     |      Milestone:         
Component:  Compiler   |        Version:  6.8.1  
 Severity:  normal     |     Resolution:         
 Keywords:             |     Difficulty:  Unknown
 Testcase:             |   Architecture:  Unknown
       Os:  Unknown    |  
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Comment (by JulesBean):

 No.

 One them has to commit first. When it commits, it sets all the entries to
 something (say, 1). At this point, the other one has made no visible
 changes (all its changes are private, in its transaction log). Then, the
 other one commits, and it sets them all to 0.

 Committing is atomic.

 In the current situation what would happen is the first would commit, and
 then the second would say "erk! something has changed!" and not commit.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2028#comment:3>
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