Re: [log4cxx-users] Singleton class causes segfault at termination

[Stefan Borovac]

Hi Oscar,

just a guess. You are using an auto_pointer. That's
not necessary as LoggerPtr is already a smart pointer.

I had similar problems in the past. I have also designed a singleton
which wrapps log4cxx and end up in massive termination problems.

Maybe it helps.

Cheers
  Stefan

Oscar Pereira wrote:

Hello all,

I have developed a C++ class (a sort of singleton..) to allow the same instance of the logger to be used in several places. The code is shown at the end of the email message.

In main, I just do this:

int main()
{
 LOG4CXX_WARN(CLogger::GetLoggerInstance(), "hello");
 return 0;
}

and the program segfaults. Running it inside gdb yields this backtrace:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1219492160 (LWP 18963)]
0xb7aa6cfa in apr_pool_destroy () from /usr/lib/libapr-1.so.0
(gdb) bt
#0  0xb7aa6cfa in apr_pool_destroy () from /usr/lib/libapr-1.so.0
#1  0xb7e5e4f5 in ~Pool (this=0x805f234) at pool.cpp:46

#2 0xb7de7504 in ~AppenderSkeleton (this=0x805f200, __vtt_parm=0xb7f020e4) at ../../../src/main/include/log4cxx/appenderskeleton.h:48

#3  0xb7e8540d in ~SyslogAppender (this=0x805f200) at syslogappender.cpp:93

#4 0xb7e4c6f5 in log4cxx::helpers::ObjectImpl::releaseRef (this=0x805f254) at objectimpl.cpp:46 #5 0xb7de0bc2 in log4cxx::AppenderSkeleton::releaseRef (this=0x805f200) at appenderskeleton.cpp:68 #6 0xb7de002e in ~ObjectPtrT (this=0x805e810) at ../../../src/main/include/log4cxx/helpers/objectptr.h:100 #7 0xb7de0377 in ~AppenderAttachableImpl (this=0x805f048) at /usr/include/c++/4.1.3/bits/stl_construct.h:107 #8 0xb7e4c6f5 in log4cxx::helpers::ObjectImpl::releaseRef (this=0x805f05c) at objectimpl.cpp:46 #9 0xb7ddef82 in log4cxx::helpers::AppenderAttachableImpl::releaseRef (this=0x805f048) at appenderattachableimpl.cpp:41 #10 0xb7e3ad93 in ~Logger (this=0x8057ab0) at ../../../src/main/include/log4cxx/helpers/objectptr.h:100 #11 0xb7e4c6f5 in log4cxx::helpers::ObjectImpl::releaseRef (this=0x8057ae8) at objectimpl.cpp:46 #12 0xb7e365d2 in log4cxx::Logger::releaseRef (this=0x8057ab0) at logger.cpp:62 #13 0xb7de7d27 in ~ObjectPtrT (this=0x804b6f0) at ../../../src/main/include/log4cxx/helpers/objectptr.h:100 #14 0x08049355 in ~auto_ptr (this=0x804ae90) at /usr/include/c++/4.1.3/memory:259

#15 0x08049100 in __tcf_1 () at CLogger.cpp:15
#16 0xb7afd594 in exit () from /lib/tls/i686/cmov/libc.so.6
#17 0xb7ae6058 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#18 0x08049071 in _start ()

(gdb) Can anyone make any sense of this? The logmanager part is something that I tried to see if that kept the program from segfaulting...

Thanks in advance,
Oscar

-----------Singleton Code-------------------

//file CLogger.hh
#pragma once

#include <log4cxx/logger.h>

class CLogger
{
 public:
   static log4cxx::LoggerPtr& GetLoggerInstance(void);
   static void initializeMpsLogger(const char* configure_path);
   ~CLogger(void) { }
   static void quit(void);

 private:
   static std::auto_ptr<log4cxx::LoggerPtr> m_pLoggerInstance;
   static const char* m_cConfigurationFile;
   CLogger(void);
};

//CLogger.cpp
#include "CLogger.hh"

#include <iostream> /* for stderr */

#include <log4cxx/propertyconfigurator.h>
#include <log4cxx/logmanager.h>

using std::cerr;
using std::endl;

using log4cxx::LoggerPtr;
using log4cxx::Logger;
using log4cxx::PropertyConfigurator;

std::auto_ptr<log4cxx::LoggerPtr> CLogger::m_pLoggerInstance;
const char* CLogger::m_cConfigurationFile="./log4cxx.config";

CLogger::CLogger(void){
}

LoggerPtr& CLogger::GetLoggerInstance(void){
 if (m_pLoggerInstance.get() == 0){
   m_pLoggerInstance.reset(new LoggerPtr(Logger::getLogger("mps")));
   try{
     PropertyConfigurator::configure(m_cConfigurationFile);
   }catch(std::exception& e){

cerr << "Error while configuring logger using conf file "<< m_cConfigurationFile << endl;

   }
 }
 return *m_pLoggerInstance;
}

void CLogger::initializeMpsLogger(const char* configure_path)
{
 m_cConfigurationFile = configure_path;
}

void CLogger::quit(void){
 log4cxx::LogManager::shutdown();
}