Re: [Haskell-cafe] Why don't my OS threads terminate?

On 10/03/11 18:20, Bas van Dijk wrote:

On 10 March 2011 18:11, Simon Marlow wrote:

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On 28/02/11 15:59, Bas van Dijk wrote:

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On 25 February 2011 19:10, Bas van Dijk wrote:

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On 25 February 2011 18:27, sclv wrote:

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Bas van Dijk-2 wrote:

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I believe the OS threads are created by my levmar library. This library uses bindings-levmar[4] which is a binding to a C library. bindings-levmar uses safe FFI calls because the levmar C procedures are reentrant (they need to call back into Haskell to execute the model function). I believe the RTS creates an OS thread for each safe FFI call.

Sounds like #4262: http://hackage.haskell.org/trac/ghc/ticket/4262

(Should be fixed in head)

That looks exactly like my problem. I will try it out with ghc head on monday.

In ghc-HEAD (7.1.20110227) the bug is fixed, great!

The bug still appears in ghc-7.0.2-rc2, so I assume the patch in #4262 was not merged in that release.

Will it be merged into the upcoming ghc-7.0.2?

I'm slightly worried by this. #4262 was not an OS thread "leak", but rather that when the program needs fewer OS threads we weren't returning the surplus OS threads back to the system. #4262 doesn't make programs use an ever-increasing number of OS threads. It's an optimisation rather than a bug, which is why we didn't merge the patch into the 7.0 branch.

So I'm concerned because the symptom you describe sounds more like a leak. #4850 could have caused it, but the fix for that was merged into 7.0.2.

My bug is solved in 7.0.2.

Ah great, thanks for testing. Cheers, Simon