commit 2e6f1ae9c: breaks blead #15945
Comments
From @khwilliamsonThis is a bug report for perl from khw@cpan.org, commit 2e6f1ae fix and test execution of non-empty .bs files This commit consistently causes this: panic: free from wrong pool, eea800!=d40c20 during global destruction. but only under certain circumstances. One that threw us off scent, is I am using ccache. I have tried clearing it before running, with no You can see the Configure options below. I run on an 8-core system with Flags: Site configuration information for perl 5.26.0: Configured by khw at Fri Apr 7 16:55:52 MDT 2017. Summary of my perl5 (revision 5 version 26 subversion 0) configuration: @INC for perl 5.26.0: Environment for perl 5.26.0: PATH=/usr/lib/ccache:/home/khw/bin:/home/khw/perl5/perlbrew/bin:/home/khw/print/bin:/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/usr/games:/usr/local/games:/home/khw/iands/www:/home/khw/cxoffice/bin |
From @jkeenanOn Sat, 08 Apr 2017 04:43:13 GMT, public@khwilliamson.com wrote:
I have not been able to reproduce this problem. I configured like this: ##### ... then called 'make test_harness' in a terminal where $TEST_JOBS = 8 and I have 4 cores. All tests PASSed. I then changed the name of the directory from 'blead' to 'rando', then reconfigured changing only the last switch. Again, all tests PASSed. I did not use ccache in either case. In situations like this I try to start from as few switches as possible and add switches until the problem occurs. Conversely, you could also start subtracting switches from what you currently have. I know from backscrolling #p5p that you've done some of that. (I should note that normally I configure with just '-des -Dusedevel' with possibly '-Duseithreads'. 'make' runs without warnings for me. But with all your switches, I get warnings like this: ##### End parenthesis.) And, as you note, your @INC looks very strange. Thank you very much. -- |
|
The RT System itself - Status changed from 'new' to 'open' |
From @iabynOn Fri, Apr 07, 2017 at 09:43:13PM -0700, karl williamson wrote:
Is it definitely object2.t which is generating the panic? cd dist/threads-shared/ And if so can the test sccipt be reduced, e.g. perhaps just loading an Alternatively, if you reduce your Configure options, does the problem go -- |
From @khwilliamsonOn 04/10/2017 04:55 AM, Dave Mitchell wrote:
Test Summary Report ../dist/threads-shared/t/object2.t (Wstat: I'm now trying your other ideas. |
From @khwilliamsonOn 04/10/2017 04:55 AM, Dave Mitchell wrote:
The problem doesn't arise when running the test in isolation. I already The line of code that changed to cause the problem, is indeed The problem persists when I whittle down the Configure script to /bin/sh ./Configure -des '-Dprefix=/home/khw/tempdevel' -Dusedevel That means it fails for both gcc and g++, and both -O0 and -O2. tempdevel/ is empty. I removed the earlier /home/khw/devel. And, now I tried this on my laptop, which has a later gcc, and only 4 cores, and |
From @iabynOn Mon, Apr 10, 2017 at 12:38:21PM -0600, Karl Williamson wrote:
Does it require running multiple jobs in parallel to fail? So does ./perl harness ../dist/threads-shared/t/object2.t on its own fail? If not, how about running just a minimal number of tests HARNESS_OPTIONS=j8 ./perl harness ../dist/threads-shared/t/object2.t \ If harness fails with just the one test script, then maybe invoking PERL5LIB=../../lib:../../t Other than that I'm totally bemused. -- |
From @khwilliamsonOn 04/10/2017 05:08 PM, Dave Mitchell wrote:
No If not, how about running just a minimal number of tests
I haven't tried this, but I did try a make test.valgrind with 12
|
From @khwilliamsonOn 04/10/2017 09:09 PM, Karl Williamson wrote:
I managed to get this to fail on an individual run, by grepping for all EMXSHELL=sh PERL_DL_NONLAZY=1 ../../perl -I../.. -MTestInit=U2T Removing either of the environment settings causes it to not fail. The If I add PERL5LIB=../../lib:../../t it also succeeds, which makes me |
From @iabynOn Tue, Apr 11, 2017 at 05:01:25PM -0600, Karl Williamson wrote:
The PERL5LIB and PERL_CORE is being set by TestInit itself - I was dumping Having said that, I still can't reproduce it. Can you run it under valgrind? Also, can you run it under strace to see what files (and paths) it's -- |
From @khwilliamsonOn 04/12/2017 01:15 AM, Dave Mitchell wrote:
Both attached. |
From @khwilliamson |
From @iabynOn Wed, Apr 12, 2017 at 09:23:07AM -0600, Karl Williamson wrote:
The strace shows that the only interaction it's having with .bs files is stat("../../lib/auto/Cwd/Cwd.bs", 0x1221eb0) = -1 ENOENT (No such file or directory) which strongly indicates that the modified branch in XSLoader.pm is never if (-s $bs) { # only read file if it's not empty Could you temporarily replace the 'eval' line with a die to confim that If so, it would indicate that my commit only changed some code which is The valgrind stack trace shows that Perl_croak_nocontext("panic: free from wrong pool") is being called when free()ing the main threads's SV malloc()ed arenas - -- |
From @khwilliamsonOn 04/12/2017 09:48 AM, Dave Mitchell wrote:
The die doesn't get called, but the pool bug is gone too. |
From @khwilliamsonOn 04/12/2017 10:37 AM, Karl Williamson wrote:
Just to be sure, I replaced the die by opening a file and writing to it, If I uncomment the line print STDERR "BS: the panic goes away, but, and this may be important, this message gets Use of uninitialized value in subroutine entry at ../../lib/XSLoader.pm I fail to see how this could be connected except through some weirdness. |
From @iabynOn Wed, Apr 12, 2017 at 04:58:43PM -0600, Karl Williamson wrote:
That's just bizarre. Maybe run it under gdb and see where and what in the Dynaloader XS is -- |
From @khwilliamsonOn 04/13/2017 02:04 AM, Dave Mitchell wrote:
Running under valgrind did not show any errors: Here's the gdb stack trace #0 S_find_uninit_var (my_perl=0xad0c20, obase=0xb92ac8, |
From @khwilliamsonOn 04/13/2017 10:05 AM, Karl Williamson wrote:
Some more data points. I tried it compiling under clang, with I then tried uncommenting that print statement that should not be # dlutils.c before 5.006 has this: It still makes no sense to me that this should happen, given that the
|
From @iabynOn Thu, Apr 13, 2017 at 11:12:18AM -0600, Karl Williamson wrote:
It's this code in dl_generic_private_init(): #ifdef DEBUGGING Normally *DynaLoader::dl_debug doesn't exist, so sv is null. By So I think this is a red herring. Perhaps another approach concerning this panic: panic: free from wrong pool, eea800!=d40c20 during global destruction. would be to analyse it under gdb. When PERL_TRACK_MEMPOOL is defined, So run the failing process once in gdb, breakpointing on the panic line at Then do a Full backtracks at those points might illuminate things a bit. -- |
From @khwilliamsonOn 04/13/2017 12:39 PM, Dave Mitchell wrote:
... Hardware watchpoint 2: -location header->interpreter Old value = <unreadable> Thread 1 "perl" hit Hardware watchpoint 2: -location header->interpreter Old value = (PerlInterpreter *) 0xd40ae0 Thread 1 "perl" hit Breakpoint 1, Perl_safesysfree (where=0xd3b3e0) at |
From @iabynOn Thu, Apr 13, 2017 at 09:48:09PM -0600, Karl Williamson wrote:
Aha, that was the vital info I needed. Turns out the @INC changes were a commit defb77b threads::shared: alloc arenas with correct context Affected files ... Differences ... Inline Patchdiff --git a/dist/threads-shared/lib/threads/shared.pm b/dist/threads-shared/lib/threads/shared.pm
index 5a203b0..73c4dd9 100644
--- a/dist/threads-shared/lib/threads/shared.pm
+++ b/dist/threads-shared/lib/threads/shared.pm
@@ -7,7 +7,7 @@ use warnings;
use Scalar::Util qw(reftype refaddr blessed);
-our $VERSION = '1.55'; # Please update the pod, too.
+our $VERSION = '1.56'; # Please update the pod, too.
my $XS_VERSION = $VERSION;
$VERSION = eval $VERSION;
@@ -195,7 +195,7 @@ threads::shared - Perl extension for sharing data structures between threads
=head1 VERSION
-This document describes threads::shared version 1.55
+This document describes threads::shared version 1.56
=head1 SYNOPSIS
diff --git a/dist/threads-shared/shared.xs b/dist/threads-shared/shared.xs
index dab5e36..3c1b5e6 100644
--- a/dist/threads-shared/shared.xs
+++ b/dist/threads-shared/shared.xs
@@ -1104,8 +1104,9 @@ sharedsv_array_mg_CLEAR(pTHX_ SV *sv, MAGIC *mg)
if (!sv) continue;
if ( (SvOBJECT(sv) || (SvROK(sv) && (sv = SvRV(sv))))
&& SvREFCNT(sv) == 1 ) {
- SV *tmp = Perl_sv_newmortal(caller_perl);
+ SV *tmp;
PERL_SET_CONTEXT((aTHX = caller_perl));
+ tmp = sv_newmortal();
sv_upgrade(tmp, SVt_RV);
get_RV(tmp, sv);
PERL_SET_CONTEXT((aTHX = PL_sharedsv_space));
@@ -1384,8 +1385,9 @@ STORESIZE(SV *obj,IV count)
if ( (SvOBJECT(sv) || (SvROK(sv) && (sv = SvRV(sv))))
&& SvREFCNT(sv) == 1 )
{
- SV *tmp = Perl_sv_newmortal(caller_perl);
+ SV *tmp;
PERL_SET_CONTEXT((aTHX = caller_perl));
+ tmp = sv_newmortal();
sv_upgrade(tmp, SVt_RV);
get_RV(tmp, sv);
PERL_SET_CONTEXT((aTHX = PL_sharedsv_space));
diff --git a/dist/threads-shared/t/object2.t b/dist/threads-shared/t/object2.t
index 3d795b9..31c3797 100644
--- a/dist/threads-shared/t/object2.t
+++ b/dist/threads-shared/t/object2.t
@@ -17,7 +17,7 @@ use ExtUtils::testlib;
BEGIN {
$| = 1;
- print("1..131\n"); ### Number of tests that will be run ###
+ print("1..133\n"); ### Number of tests that will be run ###
};
use threads;
@@ -445,6 +445,28 @@ ok($destroyed[$ID], 'Scalar object removed from shared scalar');
::ok($count == $n, "remove array object by undef");
}
+# RT #131124
+# Emptying a shared array creates new temp SVs. If there are no spare
+# SVs, a new arena is allocated. shared.xs was mallocing a new arena
+# with the wrong perl context set, meaning that when the arena was later
+# freed, it would "panic: realloc from wrong pool"
+#
+
+{
+ threads->new(sub {
+ my @a :shared;
+ push @a, bless &threads::shared::share({}) for 1..1000;
+ undef @a; # this creates lots of temp SVs
+ })->join;
+ ok(1, "#131124 undef array doesnt panic");
+
+ threads->new(sub {
+ my @a :shared;
+ push @a, bless &threads::shared::share({}) for 1..1000;
+ @a = (); # this creates lots of temp SVs
+ })->join;
+ ok(1, "#131124 clear array doesnt panic");
+}
-- The optimist believes that he lives in the best of all possible worlds. |
From @khwilliamsonFixed by defb77b |
|
@khwilliamson - Status changed from 'open' to 'resolved' |
Migrated from rt.perl.org#131124 (status was 'resolved')
Searchable as RT131124$
The text was updated successfully, but these errors were encountered: