Bug 228 - mono-sgen crashes with assertion at sgen-major-scan-object.h:81
Summary: mono-sgen crashes with assertion at sgen-major-scan-object.h:81
Alias: None
Product: Runtime
Classification: Mono
Component: GC ()
Version: unspecified
Hardware: Macintosh Mac OS
: Highest critical
Target Milestone: ---
Assignee: Mark Probst
Depends on:
Reported: 2011-08-08 08:58 UTC by Daniel Kirstenpfad
Modified: 2012-01-09 17:49 UTC (History)
7 users (show)

Tags: crash
Is this bug a regression?: ---
Last known good build:

log / screen output with complete crash dump (9.90 KB, text/plain)
2011-08-08 08:58 UTC, Daniel Kirstenpfad
crash with current master (9.14 KB, application/octet-stream)
2011-08-17 07:43 UTC, Daniel Kirstenpfad
Small test case to reproduce this crash. (2.78 KB, application/octet-stream)
2011-11-30 14:14 UTC, Brian Luczkiewicz
Stacktrace from Terminal (3.80 KB, text/plain)
2012-01-05 13:37 UTC, PJ

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Description Daniel Kirstenpfad 2011-08-08 08:58:18 UTC
Created attachment 85 [details]
log / screen output with complete crash dump

Description of Problem:

I am using a rather complex graph database application benchmark and I want to create a number of vertices and egdes. Doing so crashes the sgen garbage collector. Using boehm-gc works without a glitch.

All sourcecode to reproduce the problem is available as open-source.

Steps to reproduce the problem:
1. clone sourcecode from here: https://github.com/sones/benchmark
2. init and update submodules
3. run "buildbenchmark.sh"
4. run "mono-sgen GraphDBBenchmark.exe in GraphDBBenchmark/bin/Debug/"
6. behold teh crash

Actual Results:


Expected Results:

not crashing

How often does this happen? 


Additional Information:
Comment 1 Mark Probst 2011-08-10 05:34:44 UTC
This works for me with mono master on darwin.  There's been a few sgen bugfixes committed recently, so if your mono is older, could you please try with master?
Comment 2 Daniel Kirstenpfad 2011-08-10 07:26:51 UTC
i've checked with the currently stable versions (2.10.3 and today 2.10.4) and had that behaviour - I will do a compile run of the master asap - which will be at last on next monday. Would be great if the bug is already patched in master and may be included in the next releases...
Comment 3 Daniel Kirstenpfad 2011-08-17 07:43:54 UTC
Created attachment 148 [details]
crash with current master
Comment 4 Daniel Kirstenpfad 2011-08-17 07:45:27 UTC
I compiled from master and got this version:

Mono JIT compiler version 2.11 (master/409d4ac Mi 17 Aug 2011 12:38:36 CEST)
Copyright (C) 2002-2011 Novell, Inc, Xamarin, Inc and Contributors. www.mono-project.com
	TLS:           normal
	SIGSEGV:       normal
	Notification:  kqueue
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	LLVM:          supported, not enabled.
	GC:            sgen

After recompiling my benchmark project I get a new crash directly at start-up - see http://bugzilla.xamarin.com/attachment.cgi?id=148
Comment 5 Daniel Kirstenpfad 2011-09-02 07:11:51 UTC
stable 2.10.5 is also crashing with the same error message
Comment 6 Miguel de Icaza [MSFT] 2011-11-12 11:11:49 UTC

Your instructions to build the benchmark are incomplete and the module does not build when I use "sh buildbenchmark.sh" there are hundreds of missing references to your libraries.

Please provide detailed build instructions.
Comment 7 Brian Luczkiewicz 2011-11-30 14:14:28 UTC
Created attachment 976 [details]
Small test case to reproduce this crash.

To reproduce:

$ dmcs t.cs && mono-sgen t.exe
Comment 8 Brian Luczkiewicz 2011-11-30 14:15:18 UTC
I've attached a small test case for this bug.

The sgen code at this location has a FIXME that seems to indicate that someone has anticipated this problem:

        case DESC_TYPE_COMPLEX:
                // FIXME:
                g_assert_not_reached ();                      <-------- line 81

The gist seems to be that valuetypes with very complicated memory layouts blow up the collector. I distilled this test case out of a much larger program, and indeed, the crash seems to happen when scanning arrays of complex valuetypes.
Comment 9 Miguel de Icaza [MSFT] 2011-11-30 14:57:46 UTC
Reopening now that we have a test case.
Comment 10 Paolo Molaro 2011-12-01 11:56:37 UTC
Fixed for the mono-2-10 branch (master has different code and the program works fine there).
Comment 11 PJ 2012-01-05 13:37:22 UTC
Created attachment 1130 [details]
Stacktrace from Terminal

Stacktrace after running "dmcs t.cs && mono-sgen t.exe" on the provided t.cs.
Comment 12 PJ 2012-01-05 13:39:51 UTC
Re-opening. Duplicated bug on:
Mono 2.10.8
MonoTouch 5.0.4
MacOS 10.7.2
Comment 13 Miguel de Icaza [MSFT] 2012-01-09 15:22:39 UTC
PJ, what you are experiencing is a different bug.   The original bug was related to the GC lacking support for certain kinds of types, and what you seem to be triggering is a bug somewhere else.

I filed a new bug for this problem 2810, but I am unable to reproduce it myself.
Comment 14 PJ 2012-01-09 17:49:54 UTC
I've added info to 2810. If anyone has a suggestion on how to verify this particular bug let me know. Thanks!