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Postings from July 2022
Hi All!
I'm working on a new feature for plperl in postgresql to populate some
metadata in main::_FN for running plperl functions from postgres sql.
I've snipped out some extra code that's unrelated to focus on the issue
at hand. If the section labeled 'Leaking Section' is entirely
commented out (and of course the related SvREFCNT_dec_current is
commented as well), then there's no memory issue at all. If I do use
this section of code, something is not freed and I'm not sure what that
is, since I'm very new to perl-c
/*
* Decrement the refcount of the given SV within the active Perl
interpreter
*
* This is handy because it reloads the active-interpreter pointer, saving
* some notation in callers that switch the active interpreter.
*/
static inline void
SvREFCNT_dec_current(SV *sv)
{
dTHX;
SvREFCNT_dec(sv);
}
static SV *
plperl_call_perl_func(plperl_proc_desc *desc, FunctionCallInfo fcinfo)
{
dTHX;
dSP;
HV *hv; // hash
SV *FNsv; // scalar reference to the
hash
SV *svFN; // local reference to the
hash?
ENTER;
SAVETMPS;
/* Give functions some metadata about what's going on in $_FN
(Similar to $_TD for triggers) */
// Leaking Section {
FNsv = get_sv("main::_FN", GV_ADD);
save_item(FNsv); /* local $_FN */
hv = newHV(); // create new hash
hv_ksplit(hv, 12); /* pre-grow the hash */
hv_store_string(hv, "name", cstr2sv(desc->proname));
svFN = newRV_noinc((SV *) hv); // reference to the new hash
sv_setsv(FNsv, svFN);
// Leaking Section }
// dostuff
SvREFCNT_dec_current(hv);
PUTBACK;
FREETMPS;
LEAVE;
...snip...
}
If anyone would like to see the full context, I've attached the entire
file. My additions are between the 'New..........' sections
My question is... the perl-c api docs do not make it clear for which
allocations or accesses that you need to decrement the ref count.
Does 'hv' need a decrement?
Does 'FNsv' need a decrement?
Does 'svFN' need a decrement?
Given that: If the code for storing main::_FN is commented out
completely -- there is no memory leak... I'm pretty sure this is the
source of the leak. And being that I don't understand when you're
supposed to decrement... it's probably in this code that the issue lays.
Thanks!
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