Re: [Felix-language] Grr

[john skaller]

On 01/11/2011, at 4:27 PM, john skaller wrote:

> 
> On 01/11/2011, at 1:30 PM, john skaller wrote:
>> 
>> Grrr .. 
>> 
>> ~/felix>tools/flx_ls . '.*\.flx'
>> Segmentation fault
> 
> 
> Sigh .. looks like a bug in RE2 corrupting memory.. all these bugs are 
> tiresome ..
> the idea of Felix is to get rid of these bugs ..:]

Hmm actually looks like the gc is at fault:


d=build/release/tut/migration/mig-4-1.hpp
d=build/release/tut/migration/mig-4-1.includes
d=build/release/tut/migration/mig-4-1.o
d=build/release/tut/migration/mig-4-1.os
d=build/release/tut/migration/mig-4-1.par2
d=build/release/tut/migration/mig-4-1.resh
d=build/release/tut/migration/mig-4-1.rtti
d=build/release/tut/migration/mig-4-1.static.stdout
Actually collect
actually collected 611893 objects, still allocated 52372 bytes
Actually collect
actually collected 618089 objects, still allocated 110580 bytes
Actually collect
actually collected 615178 objects, still allocated 157156 bytes
Actually collect
actually collected 612940 objects, still allocated 192964 bytes
d=build/release/tut/tutorial/tut-01.01-0
Segmentation fault

The fault is RE2::Match(), but it happens on the first call after a collection.
So we have to bet the collector is screwing something up.

This line is a bit interesting:

pv <- C_hack::cast[word] (new dst);

This is assigning a pointer to a heap allocated copy of the string dst
to the location pointed at by pv (the value store of the JudySL array).

This object should be managed by the GC, and, scanned by the GC.

Actually looking at the program .. I'm wondering what the heck it is being 
collected!

And so now a theory: nothing should be collected. There are no heap objects
floating around in this code .. except the judy array:

    var ds = JSLArray ();

And this is the problem. The Judy array is on the STACK. So it isn't managed.
It should be on the heap, otherwise all those "new" strings it is storing
as values will be reaped. Exactly why this causes a problem is a mystery 
however..


--
john skaller
skal...@users.sourceforge.net





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