#15727: bug: all generations are collected sequentially when compacting collection kicks in -------------------------------------+------------------------------------- Reporter: lolotp | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 8.6.1 System | 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: -------------------------------------+------------------------------------- According to GHC documentation [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/runtime_cont... #rts-options-to-control-the-garbage-collector here], compacting collection should only be used for the oldest generation. I found out however while testing one of our programs that when compacting kicks in, Gen 0 were not being collected in parallel as well. Looking at the code, the bug looks to be [https://github.com/ghc/ghc/blob/5d5307f943d7581d7013ffe20af22233273fba06/rts... here], fixing this should be a simple change to the condition in the if phrase. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15727 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler