Re: Issues using statprof (no samples taken)

[Boris Zbarsky <bzbarsky@MIT.EDU>]

Ludovic Courtès wrote:
>> I can't check the values in the structs it's passed, unfortunately (no
>> symbols here for guile or the libc).
> 
> Maybe with `strace(1)' or similar?

Unfortunately, that just shows the pointer to the struct, not the value 
in the struct itself....

>>> Another (remote) possibility could be that the Scheme-level handler is
>>> not called, even though the C handler in libguile is called, since
>>> Scheme-level signal handlers are actually asyncs (info "(guile)
>>> Asyncs").  You can try to force the execution of asyncs by adding a call
>>> like "(select '() '() '() 0)" (technically, it invokes `SCM_TICK', which
>>> runs asyncs).
>> Where would I add that?
> 
> In some Scheme code that is run regularly.

I tried adding that call to code that certainly runs repeatedly between 
statprof-start and statprof-stop (the code that handles updating the 
gnucash progress bar, in fact), but that doesn't seem to help.

> BTW, is Gnucash multithreaded?

I'm not sure.  It does update the UI during execution of guile code 
(progress indicator, and so forth), but that could also be accomplished 
if the guile interpreter makes some sort of periodic callbacks into the 
embedding.  They link to pthread, but don't seem to really use it for 
anything...

>> For that matter, what's the C handler in
>> libguile?  I should be able to breakpoint on that and see whether it's
>> called, hopefully...
> 
> It's `take_signal ()' (scmsigs.c), at least in 1.8.x.

Yeah, that's called for SIGPROF in this case.  But the scheme handler is 
still not called, even with the (select '() '() '() 0) calls as above.

-Boris