#14725: memory leak: forkOS not releasing thread local `Task` struct upon end of thread -------------------------------------+------------------------------------- Reporter: RobertZabel | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 8.2.2 Resolution: | Keywords: forkOS memory | leak Operating System: POSIX | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by RobertZabel: Old description:

I came to notice a memory leak in the runtime system while letting warp use `forkOS` and conducting a load test.\\ A minimal snippet to reproduce:

{{{#!hs module Main where import Control.Concurrent

main :: IO () main = replicateM_ 10000000 $ forkOS $ return () }}}

This patch will clean up the thread local `Task` struct just before threads created by forkOS terminate.

{{{ diff --git a/rts/posix/OSThreads.c b/rts/posix/OSThreads.c index c9adf4e..bd4e75d 100644 --- a/rts/posix/OSThreads.c +++ b/rts/posix/OSThreads.c @@ -223,6 +223,7 @@ forkOS_createThreadWrapper ( void * entry ) cap = rts_lock(); rts_evalStableIO(&cap, (HsStablePtr) entry, NULL); rts_unlock(cap); + rts_done(); return NULL; } }}}

I think win32 platforms need an equivalent patch, but unfortunately I cannot verify that. \\ Hence I'm only targeting posix here.

New description: I came to notice a memory leak in the runtime system while letting warp use `forkOS` and conducting a load test.\\ A minimal snippet to reproduce: {{{#!hs module Main where import Control.Concurrent import Control.Monad main :: IO () main = replicateM_ 10000000 $ forkOS $ return () }}} This patch will clean up the thread local `Task` struct just before threads created by forkOS terminate. {{{ diff --git a/rts/posix/OSThreads.c b/rts/posix/OSThreads.c index c9adf4e..bd4e75d 100644 --- a/rts/posix/OSThreads.c +++ b/rts/posix/OSThreads.c @@ -223,6 +223,7 @@ forkOS_createThreadWrapper ( void * entry ) cap = rts_lock(); rts_evalStableIO(&cap, (HsStablePtr) entry, NULL); rts_unlock(cap); + rts_done(); return NULL; } }}} I think win32 platforms need an equivalent patch, but unfortunately I cannot verify that. \\ Hence I'm only targeting posix here. -- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14725#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler