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Date: Mon, 23 Nov 2015 03:27:05 -0700
From: "John Hein" <3fbmqnhaz4 AT snkmail DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Cygwin multithreading performance
In-Reply-To: <5652C402.7040006@maxrnd.com>
References: <CABPLASTtRK4mNxh0M_AnZgjJQ15kWPx+L=U=VCU3Wwi7jV_57A AT mail DOT gmail DOT com> <564E3017 DOT 90205 AT maxrnd DOT com> <CABPLASTLrH_udLuu2F-m5P6dkENW1Z4YHEudp4NG0-FGLJgPMg AT mail DOT gmail DOT com> <5650379B DOT 4030405 AT maxrnd DOT com>	<20151121105301 DOT GE2755 AT calimero DOT vinschen DOT de> <5652C402 DOT 7040006 AT maxrnd DOT com>

Mark Geisert wrote at 23:45 -0800 on Nov 22, 2015:
 > Corinna Vinschen wrote:
 > > On Nov 21 01:21, Mark Geisert wrote:
 > [...] so I wonder if there's
 > >> some unintentional serialization going on somewhere, but I don't know yet
 > >> how I could verify that theory.
 > >
 > > If I'm allowed to make an educated guess, the big serializer in Cygwin
 > > are probably the calls to malloc, calloc, realloc, free.  We desperately
 > > need a new malloc implementation better suited to multi-threading.
 > 
 > That's very helpful to know.  I'd want to first make sure the heavy lock 
 > activity I'm seeing in the traces really is due to malloc() and friends 
 > but I couldn't help a speculative search online for multithread-safe 
 > malloc().  These turned up:
 >      tcmalloc - part of google-perftools, requires libunwind, evidently 
 > not yet ported to Windows AFAICT,
 >      nedmalloc - http://www.nedprod.com/programs/portable/nedmalloc/
 >      ptmalloc - http://www.malloc.de/
 > 
 > The latter two are based on Doug Lea's dlmalloc which is also the basis 
 > of Cygwin's malloc() functions.  As I understand it, ptmalloc in one 
 > form or another has been part of glibc on Linux for some time.
 > 
 > So there may be a solution in sight if we need to go that direction.  Of 
 > course, SHTDI as usual :).
 > 
 > ...mark

Someone recently mentioned on this list they were working on porting
jemalloc.  That would be a good choice.

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