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From Dave Birdsall <dave.birds...@esgyn.com>
Subject RE: log4cxx crashes on application exit
Date Mon, 22 May 2017 18:48:07 GMT
Hi,

Looking at your stack more carefully, it looks like the ObjectPtrT global object is created
by the log4cxx code itself. Which makes things harder. It looks like it is trying to destroy
some underlying objects. The Hierarchy destructor seems to be making use of ObjectPtrT and
some other things. Perhaps there is a way to clean out the Hierarchy object first so that
there is nothing for it to destroy?

Dave

From: Dave Birdsall [mailto:dave.birdsall@esgyn.com]
Sent: Monday, May 22, 2017 11:43 AM
To: Log4CXX User <log4cxx-user@logging.apache.org>
Subject: RE: log4cxx crashes on application exit

I am not a log4cxx expert, but this looks a bit like the old global-object-destructor problem.

After a C++ program calls exit(), the destructors for all global objects are called. The order
is non-deterministic, and cannot be influenced by the programmer. The order is determined
at link edit time. Up until now, you have been lucky and the destructors were called in a
nice order. But now it appears they are not.

In your case, it looks like an ObjectPtrT object is being destroyed.

The best way to avoid these kinds of problems is to avoid using global C++ objects. If you
simply must, one workaround is to use a global pointer to a C++ object, initialized to null,
and wrap all accesses to that pointer with code that checks for null, creates the object if
so, and stores the pointer. Then at exit time, you can write code to explicitly destroy the
object (if you care), before calling exit(). This workaround is not ideal; it is not thread-safe,
for example. But you can cause object instances to be created in your main before spinning
up other threads.

Dave

From: Bonneau, Guy [mailto:Guy.Bonneau@grassvalley.com]
Sent: Monday, May 22, 2017 11:31 AM
To: log4cxx-user@logging.apache.org<mailto:log4cxx-user@logging.apache.org>
Subject: log4cxx crashes on application exit


We have used log4cxx V0_10_0 since a few years with both Linux and Windows without any issues
until now. We have a setup to compile and build the log4cxx shared library on both Linux and
Window. We made a solution (sln) that can build with Microsoft VS 2008 up to VS 2013. Our
log4cxx is build under gentoo for Linux.



We recently started to have a crash with a testing application under Linux Gentoo when a testing
application exit and the destruction of the static singletons of the log4cxx library proceed.
However the same testing application doesn't crash under Windows with VS 2013. We would appreciate
at any hints that could help us fix the crash issue under Linux. The stack of the crash is:

#0  0x00007f2cde67d805 in ?? () from /lib64/libc.so.6
#1  0x00007f2cde67e878 in ?? () from /lib64/libc.so.6
#2  0x00007f2ce7b829b3 in std::_Rb_tree<std::string, std::pair<std::string const, log4cxx::helpers::ObjectPtrT<log4cxx::Logger>
>, std::_Select1st<std::pair<std::string const, log4cxx::helpers::ObjectPtrT<log4cxx::Logger>
> >, std::less<std::string>, std::allocator<std::pair<std::string const,
log4cxx::helpers::ObjectPtrT<log4cxx::Logger> > > >::_M_erase(std::_Rb_tree_node<std::pair<std::string
const, log4cxx::helpers::ObjectPtrT<log4cxx::Logger> > >*) () from /usr/lib64/liblog4cxx.so.10
#3  0x00007f2ce7b80940 in log4cxx::Hierarchy::~Hierarchy() () from /usr/lib64/liblog4cxx.so.10
#4  0x00007f2ce7b80b99 in log4cxx::Hierarchy::~Hierarchy() () from /usr/lib64/liblog4cxx.so.10
#5  0x00007f2ce7b98c46 in log4cxx::spi::DefaultRepositorySelector::~DefaultRepositorySelector()
() from /usr/lib64/liblog4cxx.so.10
#6  0x00007f2ce7b989c0 in log4cxx::helpers::ObjectPtrT<log4cxx::spi::RepositorySelector>::~ObjectPtrT()
() from /usr/lib64/liblog4cxx.so.10
#7  0x00007f2cde63beef in __cxa_finalize () from /lib64/libc.so.6
#8  0x00007f2ce7b4ab33 in ?? () from /usr/lib64/liblog4cxx.so.10‚Äč



Thanks

Guy Bonneau




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