Breakpad does not catch crash in QThread

[Kristian Karl]

Hi,

I have following code:

============== crasch.cpp ======================
#include <QThread>
#include "client/linux/handler/exception_handler.h"

class MyThread : public QThread {
public:
virtual void run();
void crash();
};

void MyThread::run() {
crash();
}

void MyThread::crash() {
volatile int* a = (int*)(NULL);
*a = 1;
}

static bool dumpCallback(const char* dump_path, const char*
minidump_id, void*, bool succeeded) {
if (succeeded) {
printf("Dump path: %s/%s.dmp\n", dump_path, minidump_id);
} else {
printf("Failed to write crash dump\n");
}
return succeeded;
}

int main(int, char **){
google_breakpad::ExceptionHandler eh("/tmp", NULL, dumpCallback,
NULL, true);
MyThread a;
a.start();
return 0;
}
============== end of crasch.cpp ======================

============== crasch.pro ======================
TEMPLATE = app
SOURCES = crash.cpp
CONFIG += console
INCLUDEPATH += /home/krikar/Tools/google-breakpad/trunk/src
============== end of crasch.pro ======================

Now when I build an run the code:
krikar@krikar-desktop:~/foo$ qmake crash.pro
krikar@krikar-desktop:~/foo$ make
g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -
DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/
include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I../
Tools/google-breakpad/trunk/src -I. -o crash.o crash.cpp
g++ -Wl,-O1 -o crash crash.o -L/usr/lib -lbreakpad_client -lQtGui -
lQtCore -lpthread
krikar@krikar-desktop:~/foo$ ./crash
QThread: Destroyed while thread is still running
krikar@krikar-desktop:~/foo$

Google breakpad does not catch the crash. Why? I have similar problmes
in other QThread apps, where breakpad actually catches a crash in a
thread, but writes empty minidump files.

[Kristian Karl]

And I forgot to tell you, that I ran this on a 64-bit ubuntu using
libqt4-dev 4.7.0 with svn r774 from breakpad.
/Kristian

[Jimmy Bahuleyan]

There is nothing wrong with breakpad here. You must stop your
application from exiting before the child thread gets a chance to
execute. Try adding a.wait() below a.start()

-jb

[Kristian Karl]

> There is nothing wrong with breakpad here. You must stop your
> application from exiting before the child thread gets a chance to
> execute. Try adding a.wait() below a.start()
>
> -jb

You're absolutely right! I forgot a.wait(); But when I run the updated
version below, I get:

Failed to write crash dump

Segmentation fault

And in the /tmp folder, there is an empty dump file:

ls -ltr /tmp/
-rw------- 1 krikar krikar 0 2011-03-07 14:51
6b99e91c-7b50-65d5-67ad3454-7860368c.dmp

============== crasch.cpp ======================
#include <QThread>
#include "client/linux/handler/exception_handler.h"

class MyThread : public QThread {
public:
virtual void run();
void crash();
};

void MyThread::run() {
crash();
}

void MyThread::crash() {
volatile int* a = (int*)(NULL);
*a = 1;
}

static bool dumpCallback(const char* dump_path, const char*
minidump_id, void*, bool succeeded) {
if (succeeded) {
printf("Dump path: %s/%s.dmp\n", dump_path, minidump_id);
} else {
printf("Failed to write crash dump\n");
}
return succeeded;
}

int main(int, char **){
google_breakpad::ExceptionHandler eh("/tmp", NULL, dumpCallback,
NULL, true);
MyThread a;
a.start();

a.wait();

return 0;
}
============== end of crasch.cpp ======================

============== crasch.pro ======================
TEMPLATE = app
SOURCES = crash.cpp
CONFIG += console

INCLUDEPATH += /home/krikar/Tools/breakpad/trunk/src
LIBS += -L/usr/local/lib -lbreakpad_client

[Kristian Karl]

Running with elevated privileges helps.
sudo ./crash
Dump path: /tmp/3d24d02e-add3-bfba-7fc4513e-474f4124.dmp
Segmentation fault

I found this:
http://groups.google.com/group/google-breakpad-dev/browse_thread/thread/38091af0d8695a5/fa0fe29bb3fc42e9?lnk=gst&q=ptrace#fa0fe29bb3fc42e9

I'm running Ubuntu 10.10
uname -r => 2.6.35-28-generic


On Mar 7, 4:20 pm, Kristian Karl <kristian.hermann.k...@gmail.com>
wrote:

[Ted Mielczarek]

On Mon, Mar 7, 2011 at 11:39 AM, Kristian Karl
<kristian.h...@gmail.com> wrote:
> Running with elevated privileges helps.
>  sudo ./crash
>  Dump path: /tmp/3d24d02e-add3-bfba-7fc4513e-474f4124.dmp
>  Segmentation fault
>
> I found this:
> http://groups.google.com/group/google-breakpad-dev/browse_thread/thread/38091af0d8695a5/fa0fe29bb3fc42e9?lnk=gst&q=ptrace#fa0fe29bb3fc42e9
>
> I'm running Ubuntu 10.10
> uname -r => 2.6.35-28-generic

Those changes landed a while back:
http://code.google.com/p/google-breakpad/source/detail?r=673

CCing Chris Coulson, who wrote the patch. AFAIK things should work on
Ubuntu 10.10.

-Ted

[Kristian Karl]

Actually may be a bug in ubuntu
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/729839
/Kristian

[Chris Coulson]

(Trying a second time - my first mail got rejected).

Quite possibly. I know that Breakpad does not work from Chrome on Ubuntu
at the moment, although it does work for Firefox. At some point this
week I'll be investigating that, but the bug report you've pointed out
might be a good starting point for me.

Regards
Chris

[Lei Zhang]

On Maverick, Chromium has problems with dumping renderer crashes when
the renderer is sandboxed. There's no problem with dumping browser
crashes. This is http://crbug.com/56730.