[plt-scheme] Random PLT Boehm pauses under Win2000/PLT203

From: Eric Kidd (eric.kidd at pobox.com)
Date: Mon Aug 25 17:24:04 EDT 2003

On Mon, 2003-08-25 at 17:10, Matthew Flatt wrote:
> Thanks for lots of information, but two more questions:
>  1. How do you know that the pauses are GC pauses?

Sorry.  :-)  If I use MSVC to drop into the debugger during a pause, I
always wind up somewhere deep in Boehm, usually in one of the high-speed
heap scanning routines.

However, because I could immediately end the pause (on one machine) by
hitting Conrol-Alt-Delete and clicking on "Cancel", I worry whether
Boehm is interacting with the OS in some unfortunate fashion.  It
doesn't look like Boehm is CPU-bound--if it were,
Control-Alt-Delete/Cancel would not make the pauses end early.

But not all of the systems appear to respond to this trick, so I might
be seeing several separate problems with similar symptoms.

>  2. Do you know whether the pauses are related to finalization (which
>     happens at the end of a collection proper)?

I don't *think* so.  Whenever I drop into the debugger, it looks like
Boehm is still scanning for things which look like pointers.

I can probably arrange stack traces tomorrow, if the owners of the
affected machines are in the office.  I can also provide source,
executables and sample code for our application.

I'm willing to consider alternate GCs, heavy debugging, bugging my boss
to hire experts, etc.

Thank you for your quick response!


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