Re: Having memory leak issues with perl-c
Mark Murawski <[email protected]> Fri, 12 Aug 2022 18:11:10 -0400
| Newsgroups | gmane.comp.lang.perl.quality-assurance |
|---|---|
| Message-ID | <[email protected]> |
--------------ITIys2QgDam9tEv63NQxGh6J Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/4/22 15:10, demerphq wrote: > On Thu, 4 Aug 2022 at 17:04, Mark Murawski > <[email protected]> wrote: > > On 8/4/22 02:50, demerphq wrote: >> On Thu, 4 Aug 2022 at 01:58, Mark Murawski >> <[email protected]> wrote: >> >> I'm still not getting something... if I want to fix the >> code-as-is and do this: >> >> FNsv = get_sv("main::_FN", GV_ADD); >> if (!FNsv) >> ereport(ERROR, >> (errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION), >> errmsg("couldn't fetch $_FN"))); >> >> save_item(FNsv); /* local $_FN */ >> >> >> I dont get the sequence here. You take the old value of >> $main::_FN and then you localize it after you fetch it? That >> seems weird. > > > You did not respond to this comment ^^ The reason for the save_item*( was because I was modeling this code on another section that uses save_item() to accomplish something similar (to send internal postgres details to some perl). I don't know why the original author uses save_item() for this purpose. > > No, you shouldn't do anything after creating the hash that might die > until you have arranged for hv to be freed. Storing into the hash > might die. Got it. > >> Obviously in perl we can write: >> >> my %hash; >> $main::_FN= \%hash; >> >> And in XS we can do the same thing. Unfortunately there isn't a >> utility sub to do this currently, it has been on my TODO list to >> add one for some time but lack of round tuits and all that. >> >> You want code something like this: >> >> sv_clear(FNsv); /* undef the sv */ >> sv_upgrade(FNsv,SVt_RV); >> SvRV_set(FNsv, (SV*)hv); >> SvROK_on(FNsv); >> >> Again, make liberal use of sv_dump() it is the XS version of >> Data::Dumper more or less. > > > Also... i get a crash when I use sv_clear(FNsv); right away like this. > > > And what does FNsv look like immediately before you call sv_clear()? I'm on vacation and I'm working on this as I get the time.... I wasn't able to attach gdb and get anything meaningful, but based on the newly added debugs you can tell where it's crashing > Can you please show a reduced version of the code? And explain why you > are doing save_item(FNsv)? And provide some of the output of sv_dump()? > save_item... details above.. And trimmed new code: // New .......... { FNsv = get_sv("main::_FN", GV_ADD); if (!FNsv) { ereport(ERROR, (errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION), errmsg("couldn't fetch $_FN"))); } fprintf(stderr, "POST get_sv\n"); sv_dump(FNsv); save_item(FNsv); /* local $_FN */ hv = newHV(); // create new hash fprintf(stderr, "PRE sv_clear/sv_upgrade/SvRV_set/SvROK_on\n"); fprintf(stderr, "PRE sv_clear\n"); sv_clear(FNsv); /* undef the sv */ fprintf(stderr, "POST sv_clear\n"); sv_dump(FNsv); fprintf(stderr, "PRE sv_upgrade svtype: %d, %d %d\n", SvTYPE(FNsv), SVt_NULL, SVt_PVIO); sv_upgrade(FNsv,SVt_RV); //SvUPGRADE(FNsv, SVt_RV); fprintf(stderr, "POST sv_upgrade\n"); sv_dump(FNsv); fprintf(stderr, "PRE sv_set/on\n"); SvRV_set(FNsv, (SV*)hv); SvROK_on(FNsv); fprintf(stderr, "POST sv_set/on\n"); sv_dump(FNsv); fprintf(stderr, "POST sv_clear/sb_upgrade/SvRV_set/SvROK_on\n"); sv_dump(FNsv); // Anything below might die().. so we do all our setup above hv_store_string(hv, "name", cstr2sv(desc->proname)); // new .............. } Output: POST get_sv SV = NULL(0x0) at 0x55adeea14e40 REFCNT = 1 FLAGS = () PRE sv_clear/sv_upgrade/SvRV_set/SvROK_on PRE sv_clear POST sv_clear SV = UNKNOWN(0xff) (0x0) at 0x55adeea14e40 REFCNT = 1 FLAGS = () PRE sv_upgrade svtype: 255, 0 15 sv_upgrade from type 255 down to type 1. 2022-08-12 17:56:57 EDT - - - - 7387 - - 0 - LOG: server process (PID 11614) was terminated by signal 11: Segmentation fault Basically my gdb session is useless and results in this: Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00007fcf6ae24c7f in ?? () (gdb) bt #0 0x00007fcf6ae24c7f in ?? () Backtrace stopped: Cannot access memory at address 0x7ffce563e4b0 Thanks! --------------ITIys2QgDam9tEv63NQxGh6J Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body> <div class="moz-cite-prefix">On 8/4/22 15:10, demerphq wrote:<br> </div> <blockquote type="cite" cite="mid:CANgJU+W95nxb9HB_EEXUo3KDYqx-1xe14TZmJG_v-RBD=evZpw@mail.gmail.com"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <div dir="ltr"> <div dir="ltr">On Thu, 4 Aug 2022 at 17:04, Mark Murawski <<a href="mailto:[email protected]" moz-do-not-send="true" class="moz-txt-link-freetext">[email protected]</a>> wrote:<br> </div> <div class="gmail_quote"> <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> <div> <div>On 8/4/22 02:50, demerphq wrote:<br> </div> <blockquote type="cite"> <div dir="ltr"> <div dir="ltr">On Thu, 4 Aug 2022 at 01:58, Mark Murawski <<a href="mailto:[email protected]" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">[email protected]</a>> wrote:<br> </div> <div class="gmail_quote"> <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> <div> <div>I'm still not getting something... if I want to fix the code-as-is and do this:<br> </div> <br> FNsv = get_sv("main::_FN", GV_ADD);<br> if (!FNsv)<br> ereport(ERROR,<br> (errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),<br> errmsg("couldn't fetch $_FN")));<br> <br> save_item(FNsv); /* local $_FN */<br> </div> </blockquote> <div><br> </div> <div>I dont get the sequence here. You take the old value of $main::_FN and then you localize it after you fetch it? That seems weird.</div> </div> </div> </blockquote> </div> </blockquote> <div><br> </div> <div>You did not respond to this comment ^^</div> </div> </div> </blockquote> <br> <br> The reason for the save_item*( was because I was modeling this code on another section that uses save_item() to accomplish something similar (to send internal postgres details to some perl). I don't know why the original author uses save_item() for this purpose.<br> <br> <br> <br> <br> <blockquote type="cite" cite="mid:CANgJU+W95nxb9HB_EEXUo3KDYqx-1xe14TZmJG_v-RBD=evZpw@mail.gmail.com"> <div dir="ltr"> <div class="gmail_quote"><br> <div>No, you shouldn't do anything after creating the hash that might die until you have arranged for hv to be freed. Storing into the hash might die.</div> </div> </div> </blockquote> <br> Got it.<br> <br> <blockquote type="cite" cite="mid:CANgJU+W95nxb9HB_EEXUo3KDYqx-1xe14TZmJG_v-RBD=evZpw@mail.gmail.com"> <div dir="ltr"> <div class="gmail_quote"> <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> <div> <br> <blockquote type="cite"> <div dir="ltr"> <div class="gmail_quote"> <div>Obviously in perl we can write:</div> <div><br> </div> <div>my %hash;</div> <div>$main::_FN= \%hash;</div> <div><br> </div> <div>And in XS we can do the same thing. Unfortunately there isn't a utility sub to do this currently, it has been on my TODO list to add one for some time but lack of round tuits and all that. </div> <div><br> </div> <div>You want code something like this:</div> <div><br> </div> <div>sv_clear(FNsv); /* undef the sv */</div> <div>sv_upgrade(FNsv,SVt_RV);</div> <div>SvRV_set(FNsv, (SV*)hv);</div> <div>SvROK_on(FNsv);</div> <div><br> </div> <div>Again, make liberal use of sv_dump() it is the XS version of <a moz-do-not-send="true">Data::Dumper</a> more or less.</div> </div> </div> </blockquote> <br> </div> </blockquote> </div> </div> </blockquote> <br> <br> <blockquote type="cite" cite="mid:CANgJU+W95nxb9HB_EEXUo3KDYqx-1xe14TZmJG_v-RBD=evZpw@mail.gmail.com"> <div dir="ltr"> <div class="gmail_quote"> <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> <div> <br> Also... i get a crash when I use sv_clear(FNsv); right away like this.<br> </div> </blockquote> <div><br> And what does FNsv look like immediately before you call sv_clear()? <br> </div> </div> </div> </blockquote> <br> <br> I'm on vacation and I'm working on this as I get the time.... I wasn't able to attach gdb and get anything meaningful, but based on the newly added debugs you can tell where it's crashing<br> <br> <br> <br> <br> <blockquote type="cite" cite="mid:CANgJU+W95nxb9HB_EEXUo3KDYqx-1xe14TZmJG_v-RBD=evZpw@mail.gmail.com"> <div dir="ltr"> <div class="gmail_quote"> <div>Can you please show a reduced version of the code? And explain why you are doing save_item(FNsv)? And provide some of the output of sv_dump()?</div> <br> </div> </div> </blockquote> <br> save_item... details above..<br> And trimmed new code:<br> <br> // New .......... {<br> FNsv = get_sv("main::_FN", GV_ADD);<br> if (!FNsv) {<br> ereport(ERROR,<br> (errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),<br> errmsg("couldn't fetch $_FN")));<br> }<br> <br> fprintf(stderr, "POST get_sv\n");<br> sv_dump(FNsv);<br> <br> save_item(FNsv); /* local $_FN */<br> <br> hv = newHV(); // create new hash<br> <br> fprintf(stderr, "PRE sv_clear/sv_upgrade/SvRV_set/SvROK_on\n");<br> <br> fprintf(stderr, "PRE sv_clear\n");<br> sv_clear(FNsv); /* undef the sv */<br> fprintf(stderr, "POST sv_clear\n");<br> sv_dump(FNsv);<br> <br> fprintf(stderr, "PRE sv_upgrade svtype: %d, %d %d\n", SvTYPE(FNsv), SVt_NULL, SVt_PVIO);<br> sv_upgrade(FNsv,SVt_RV);<br> //SvUPGRADE(FNsv, SVt_RV);<br> fprintf(stderr, "POST sv_upgrade\n");<br> sv_dump(FNsv);<br> <br> fprintf(stderr, "PRE sv_set/on\n");<br> SvRV_set(FNsv, (SV*)hv);<br> SvROK_on(FNsv);<br> fprintf(stderr, "POST sv_set/on\n");<br> sv_dump(FNsv);<br> <br> fprintf(stderr, "POST sv_clear/sb_upgrade/SvRV_set/SvROK_on\n");<br> sv_dump(FNsv);<br> <br> // Anything below might die().. so we do all our setup above<br> <br> hv_store_string(hv, "name", cstr2sv(desc->proname));<br> // new .............. }<br> <br> Output:<br> POST get_sv<br> SV = NULL(0x0) at 0x55adeea14e40<br> REFCNT = 1<br> FLAGS = ()<br> PRE sv_clear/sv_upgrade/SvRV_set/SvROK_on<br> PRE sv_clear<br> POST sv_clear<br> SV = UNKNOWN(0xff) (0x0) at 0x55adeea14e40<br> REFCNT = 1<br> FLAGS = ()<br> PRE sv_upgrade svtype: 255, 0 15<br> sv_upgrade from type 255 down to type 1.<br> 2022-08-12 17:56:57 EDT - - - - 7387 - - 0 - LOG: server process (PID 11614) was terminated by signal 11: Segmentation fault<br> <br> <br> Basically my gdb session is useless and results in this:<br> <br> Program terminated with signal SIGSEGV, Segmentation fault.<br> #0 0x00007fcf6ae24c7f in ?? ()<br> (gdb) bt<br> #0 0x00007fcf6ae24c7f in ?? ()<br> Backtrace stopped: Cannot access memory at address 0x7ffce563e4b0<br> <br> <br> <br> Thanks!<br> </body> </html> --------------ITIys2QgDam9tEv63NQxGh6J--