Re: segfault and onCleanup()

[Ben Abbott]

On Dec 8, 2011, at 6:59 AM, John W. Eaton wrote:

> On  7-Dec-2011, Rik wrote:
> 
> | On 12/07/2011 12:41 PM, John W. Eaton wrote:
> | > I'm not seeing this crash, but I checked in this change as a temporary
> | > fix for those of you who are.
> | >
> | > I don't know that I'll be able to debug this problem unless I can
> | > find a way to reproduce it myself.
> | 
> | I've single-stepped through the segfault.  The trouble is not directly in
> | cleanup_instance().  Rather the code 'delete instance;' triggers the 
> destructor
> | for the class.  The destructor defined in ov-typeinfo.h is empty, but there 
> are
> | a number of Array objects in the class and the destructor for the Array 
> class
> | is called.  It is not the first element of the Array object which triggers 
> the
> | segfault.  It seems to be the 14th but I don't know if that is the 14th 
> element
> | of the Array or the 14th Array object.  It also might simply be a red 
> herring. 
> | The relevant part of the trace is below.
> | 
> | #18 0x00002aaaad757460 in _int_free (av=0x7fffffffd1f0, p=0x0) at 
> malloc.c:5017
> | #19 0x00002aaaab1059cb in ~octave_value (this=0x63ce70, __in_chrg=<value
> | optimized out>) at ov.h:311
> | #20 0x00002aaaab106c8f in ~ArrayRep (this=0x63ce70, __in_chrg=<value 
> optimized
> | out>) at ../liboctave/Array.h:94
> | #21 0x00002aaaab106321 in ~Array (this=0x62cfe8, __in_chrg=<value optimized
> | out>) at ../liboctave/Array.h:235
> | #22 0x00002aaaab5b3582 in ~octave_value_typeinfo (this=0x62cfc0, __in_chrg=
> | <value optimized out>) at ov-typeinfo.h:192
> | #23 0x00002aaaab5b3f67 in octave_value_typeinfo::cleanup_instance () at
> | ov-typeinfo.h:223
> | #24 0x00002aaaac3ea2c8 in ~singleton_cleanup_list (this=0x612380, __in_chrg=
> | <value optimized out>) at singleton-cleanup.cc:39
> | #25 0x00002aaaab4c02a1 in singleton_cleanup_list::cleanup () at 
> ../liboctave/
> | singleton-cleanup.h:26
> | #26 0x00002aaaab4bd280 in clean_up_and_exit (retval=0) at toplev.cc:697
> | #27 0x00002aaaab46f5d1 in octave_main (argc=11, argv=0x7fffffffd1f8, 
> embedded=
> | 0) at octave.cc:904
> | #28 0x0000000000400769 in main (argc=11, argv=0x7fffffffd1f8) at main.c:35
> | 
> | Also, most of the time I can start 'run-octave' and mess around in the
> | interpreter without problems.  However, it is always reproducible with 'make
> | check'.  I did some verification with runtests and the following functions
> | always cause a segfault when exiting octave if I have used 'test XXX'.
> | 
> | ./linear-algebra/onenormest.m
> | ./geometry/griddata3.m
> | ./geometry/delaunay.m
> | ./plot/trisurf.m
> | ./plot/triplot.m
> | ./plot/trimesh.m
> | ./sparse/svds.m
> | ../src/DLD-FUNCTIONS/onCleanup.cc
> | 
> | The common element (clue?) is that they all use onCleanup within a %!test
> | block.  If I comment out the onCleanup () call then the segfault 
> disappears. 
> | Actually, on further trolling through the code, these are the only points 
> where
> | onCleanup is ever used.  I did a quick test with the following in the file
> | blah.m
> | 
> | function blah ()
> |   restore_state = onCleanup (@() disp ("hello"));
> |   disp ("First");
> | endfunction
> | 
> | Calling blah() correctly displays
> | First
> | hello
> | 
> | but this segfaults as well when I exit Octave.  This problem isn't confined 
> to
> | some weirdness of %!test blocks.
> | 
> | I'm of the opinion that the whole onCleanup class is broken.  Perhaps you 
> can
> | see quickly what is wrong.  Otherwise, the %!test blocks can be rewritten to
> | use unwind_protect blocks to accomplish the same task of restoring the 
> random
> | seed.
> 
> I don't see anything really wrong with onCleanup except that it is
> dynamically loaded.  So I checked in a change to build it into
> liboctinterp so that clearing it should not be able to cause trouble.
> 
> I also checked in some changes for gh_manager and reactivated all the
> singleton cleanup_instance functions.  As part of the gh_manager
> changes, errors in closerequestfcn callback functions should be
> handled better than I think they were before.
> 
> You'll need to be sure to remove the obsolete onCleanup.oct file
> from your build directory.
> 
> I'm not seeing any crashes now.  I've run make check multiple times and
> also ran through all the plot demos without seeing Octave crashing
> when it exits.
> 
> If you see failures, please let me know what OS (32 or 64 bit?),
> compiler version, etc. that you are using so I can try to duplicate
> the problems you are seeing.
> 
> jwe

John, I'm getting an error due to missing ov-cleanup.h. Should the #include be 
...

diff --git a/src/ov-oncleanup.cc b/src/ov-oncleanup.cc
--- a/src/ov-oncleanup.cc
+++ b/src/ov-oncleanup.cc
@@ -25,7 +25,7 @@
 #endif
 
 #include "defun.h"
-#include "ov-cleanup.h"
+#include "ov-oncleanup.h"
 #include "ov-fcn.h"
 #include "ov-usr-fcn.h"
 #include "pt-misc.h"

Ben