Any known problems with 1.4, (read-enable 'positions) and debugging?

Any known problems with 1.4, (read-enable 'positions) and debugging?

[Rob Browning]

I was trying to track down a problem in some code using 1.4, so I
turned on

	  --with-threads \
	  --enable-debug-freelist \
	  --enable-debug-malloc \
	  --enable-guile-debug

and I edited configure.in to add

  CFLAGS="$CFLAGS -DSCM_DEBUG_CELL_ACCESSES=1"

I also added to the code I was trying to test:

  (debug-enable 'backtrace)
  (debug-enable 'debug)
  (read-enable 'positions)

Then with this debugging 1.4, I ran in to a new failure (not the one I
was originally trying to diagnose) that looked like this

  3 segments total (2:6006, 1:46023, 1:24012)
      996 2-cells in segment 0
  3 segments total (2:6006, 1:46023, 1:24012)
      996 2-cells in segment 0
  Bad cell in freelist on newcell 321632: 0'th elt

After some experimentation, I found that if I commented out the
(read-enable 'positions) command, the newcell problem vanished.

Any idea why?  Is this a known issue, or is 'positions not likely to
be related to the problem.

Thanks

-- 
Rob Browning
rlb @defaultvalue.org, @linuxdevel.com, and @debian.org
Previously @cs.utexas.edu
GPG=1C58 8B2C FB5E 3F64 EA5C  64AE 78FE E5FE F0CB A0AD

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Re: Any known problems with 1.4, (read-enable 'positions) and debugging?

[Dirk Herrmann]

On Wed, 13 Mar 2002, Rob Browning wrote:

> 
> I was trying to track down a problem in some code using 1.4, so I
> turned on
> 
> 	  --with-threads \
> 	  --enable-debug-freelist \
> 	  --enable-debug-malloc \
> 	  --enable-guile-debug
> 
> and I edited configure.in to add
> 
>   CFLAGS="$CFLAGS -DSCM_DEBUG_CELL_ACCESSES=1"
> 
> I also added to the code I was trying to test:
> 
>   (debug-enable 'backtrace)
>   (debug-enable 'debug)
>   (read-enable 'positions)
> 
> Then with this debugging 1.4, I ran in to a new failure (not the one I
> was originally trying to diagnose) that looked like this
> 
>   3 segments total (2:6006, 1:46023, 1:24012)
>       996 2-cells in segment 0
>   3 segments total (2:6006, 1:46023, 1:24012)
>       996 2-cells in segment 0
>   Bad cell in freelist on newcell 321632: 0'th elt
> 
> After some experimentation, I found that if I commented out the
> (read-enable 'positions) command, the newcell problem vanished.
> 
> Any idea why?  Is this a known issue, or is 'positions not likely to
> be related to the problem.

Just to let you know, you can get (hopefully) much closer to the source of
such heap problems if you compile guile using
  make CFLAGS="-g -O2 -Wall -W -DSCM_DEBUG=1"
and then run your examples.  This enables a lot of checks, one of which is
to check every cell that is accessed for being valid.

BTW, I always run the test suite with that setting.

Best regards
Dirk Herrmann


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Re: Any known problems with 1.4, (read-enable 'positions) and debugging?

[Rob Browning]

Dirk Herrmann <dirk@ida.ing.tu-bs.de> writes:

> Just to let you know, you can get (hopefully) much closer to the source of
> such heap problems if you compile guile using
>   make CFLAGS="-g -O2 -Wall -W -DSCM_DEBUG=1"
> and then run your examples.  This enables a lot of checks, one of which is
> to check every cell that is accessed for being valid.

OK, so this isn't the same as SCM_DEBUG_CELL_ACCESSES...

> BTW, I always run the test suite with that setting.

If you happen to know, what's the relationship between
--enable-guile-debug and SCM_DEBUG?  Is there any, and would it be
appropriate to have an --enable flag for this?  I'd be happy to
specify using the flag in RELEASE as part of the testing process,
though I'd have to specify testing both with and without it since most
people won't want SCM_DEBUG for normal compiles.

Thanks

-- 
Rob Browning
rlb @defaultvalue.org, @linuxdevel.com, and @debian.org
Previously @cs.utexas.edu
GPG=1C58 8B2C FB5E 3F64 EA5C  64AE 78FE E5FE F0CB A0AD

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