#15938: Hadrian's recompilation check is extremely slow -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.8.1 Component: Build System | Version: 8.6.2 (Hadrian) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): I quickly rebuilt Hadrian with profiling and reproduced this. I used `hadrian/build.cabal.sh +RTS -p` to start Hadrian in a half-built tree and Ctrl-C'd it as soon as it started producing output (which took roughly 30 seconds of wall clock time): {{{ $ hadrian/build.cabal.sh +RTS -p Up to date Up to date | Run Ghc FindHsDependencies Stage0: libraries/ghc-heap/GHC/Exts/Heap.hs (and 7 more) => _build/stage0/libraries/ghc-heap/.dependencies.mk | Remove file _build/stage0/libraries/ghc-heap/.dependencies.mk.bak | Run Ghc CompileHs Stage0: _build/stage0/libraries/ghc- heap/build/GHC/Exts/Heap/Constants.hs => _build/stage0/libraries/ghc- heap/build/GHC/Exts/Heap/Constants.o | Run Ghc CompileHs Stage0: libraries/ghc- heap/GHC/Exts/Heap/ClosureTypes.hs => _build/stage0/libraries/ghc- heap/build/GHC/Exts/Heap/ClosureTypes.o ^CshakeArgsWith 0.000s 0% Function shake 0.465s 1% Database read 0.072s 0% With database 0.001s 0% Running rules 31.903s 98% ========================= Total 32.442s 100% user interrupt }}} I will attach the profile in a moment. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15938#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler