Re: Serious GC problem in HEAD

[Neil Jerram]

address@hidden (Ludovic Courtès) writes:

> Hi,
>
> Neil Jerram <address@hidden> writes:
>
>> That's the latest position.  My guess is that the long periods where
>> nothing happens except CPU burning are huge GCs, and that some GC bug
>> affecting multiple threads means that these GCs never actually free
>> anything (or not as much as they should, anyway).  Any ideas or other
>> datapoints would be much appreciated.  Does the Boehm GC handle
>> multiple threads?  If it does, perhaps I should try out Ludovic's
>> BGC-Guile.
>
> Is it 1.8 or HEAD?

It's HEAD.  I'll try 1.8 to see if that gives different behaviour.

> Actually, I'm suspecting my gc-stats patch [0] to cause some GC problems
> (although this is quite unexpected since it touches only stat
> information).  For instance, consider the following program:
>
>   $ guile -e '(let loop ((a 0)) (loop a))'
>
> If `guile' is HEAD, then the memory consumption of that process (as
> shown by `top') continuously increases and at a pretty high rate (!).
> If `guile' is 1.8, then that does not happen.

Interesting.  Is your gc-stats patch the only change that seems
relevant?

> I will try to dig it further and see whether/what can be done.  In the
> meantime, you could try to revert the patch.

Thanks for your input.  When I get a little time, I'll experiment with
this.

Regards,
     Neil