#9370: large blowup in memory usage and time when doing parallel build of xmlhtml package -------------------------------------+------------------------------------- Reporter: carter | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 7.8.3 Resolution: | Keywords: parmake Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: Compile- | Blocked By: time performance bug | Related Tickets: #910 #9221 Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by rwbarton): Indeed something seems to be going wrong in the simplifier when invoking ghc with -j4. {{{ *** Checking old interface for xmlhtml-0.2.3.2:Text.XmlHtml.HTML.Meta: [ 1 of 10] Compiling Text.XmlHtml.HTML.Meta ( src/Text/XmlHtml/HTML/Meta.hs, dist/build/Text/XmlHtml/HTML/Meta.o ) *** Parser: *** Renamer/typechecker: *** Desugar: Result size of Desugar (after optimization) = {terms: 26,260, types: 20,021, coercions: 0} *** Simplifier: Result size of Simplifier iteration=1 = {terms: 1,446,658, types: 953,432, coercions: 314,352} ... }}} With `-ddump-inlinings` I see this repeated over and over, which is not present with `-j1`: {{{ Inlining done: Data.String.fromString Inlining done: Data.Text.$fIsStringText Inlining done: Data.Text.pack Inlining done: Data.Text.Internal.Fusion.unstream Inlining done: Data.Text.Internal.Fusion.Common.map Inlining done: Data.Text.Internal.Fusion.Common.streamList Inlining done: Data.Text.Internal.safe Inlining done: Data.Bits.$fBitsInt_$c.&. Inlining done: Data.Text.Internal.Fusion.Types.$WYield [ repeats ~4000 times ] }}} According to `-ddump-inlinings -dverbose-core2core`, GHC never even considered inlining `fromString` with `-j1`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9370#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler