#15143: Passing an IO value through several functions results in program hanging. -------------------------------------+------------------------------------- Reporter: Burtannia | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by osa1): I made the slow program parametric on number of iterations. Seems like an exponential behavior in the generated code: {{{ $ for n ({20..30}); do time ./Slow $n; done ObsTemp 1 ./Slow $n 0,05s user 0,00s system 85% cpu 0,064 total ObsTemp 1 ./Slow $n 0,08s user 0,00s system 91% cpu 0,092 total ObsTemp 1 ./Slow $n 0,16s user 0,00s system 98% cpu 0,162 total ObsTemp 1 ./Slow $n 0,31s user 0,00s system 99% cpu 0,312 total ObsTemp 1 ./Slow $n 0,62s user 0,00s system 99% cpu 0,622 total ObsTemp 1 ./Slow $n 1,23s user 0,00s system 99% cpu 1,242 total ObsTemp 1 ./Slow $n 2,47s user 0,00s system 99% cpu 2,472 total ObsTemp 1 ./Slow $n 5,11s user 0,00s system 99% cpu 5,112 total ObsTemp 1 ./Slow $n 9,85s user 0,00s system 99% cpu 9,862 total ObsTemp 1 ./Slow $n 19,92s user 0,01s system 100% cpu 19,922 total ^C^C }}} Increasing the iteration count by one causes time it takes to double.5 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15143#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler