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Subject: Re: [Boost-build] Extremely slow gcc launches on Cygwin
From: Emil Dotchevski (emil_at_[hidden])
Date: 2010-08-20 22:00:14

On Wed, Aug 18, 2010 at 8:21 PM, Belcourt, Kenneth <kbelco_at_[hidden]> wrote:
> You were quite clear.  I was trying to eliminate large numbers of dead or
> zombie processes clogging the system.  How many total processes are running
> on the system (an idle system typically has order hundred or so)?

OK so I was just able to work on this some more, and it turned out
that the *extreme* slowdown was caused by Windows running out of
memory when running the Cygwin build. It appears it was swapping to
disk every time gcc is launched and on my old laptop which has only
1.2 gigs it crawled to a halt (no such problems when running the
Windows build on the same computer.)

On my desktop, it runs much faster (no swapping) but still very slow.
Here is a tiny bit of the build log:

common.mkdir ../../../../bin/dev/reverge/test/header-keyboard_driver~h.test
common.mkdir ../../../../bin/dev/reverge/test/header-keyboard_driver~h.test/gcc-3.4.4
common.mkdir ../../../../bin/dev/reverge/test/header-keyboard_driver~h.test/gcc-3.4.4/debug
common.mkdir ../../../../bin/dev/reverge/test/header-keyboard_driver~h.test/gcc-3.4.4/debug/link-static
**passed** ../../../../bin/dev/reverge/test/header-keyboard_driver~h.test/gcc-3.4.4/debug/link-static/header-keyboard_driver~h.test

Each mkdir takes about a second complete, each gcc launch a bit more.
It doesn't get slower with time, so at least nothing leaks (no zombies
reported by Cygwin.)

I suspect this is a general Cygwin problem with processes that have
allocated a lot of memory, but I'm still wondering if there is a way
to fix this in bjam/boost build.

Emil Dotchevski
Reverge Studios, Inc.

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