#60 Cywin program core's on "log4cpp::Catergory::shutdown()".

[Anonymous]

This program was built and executed under Cygwin. It
generates a segmentation fault and core dumps on the
"log4cpp::Catergory::shutdown()" instruction.

#include "Category.hh"
#include "FileAppender.hh"
#include "OstreamAppender.hh"
#include "BasicLayout.hh"
#include <iostream>
#include <signal.h>
#include <unistd.h>

int main(int argc, char* argv[])
{
// Handle these signals
signal(SIGUSR1, SignalHandler);
signal(SIGUSR2, SignalHandler);

// 1 instantiate an appender object that
// will append to a log file
log4cpp::Appender* app = new
log4cpp::FileAppender("FileAppender",
"/logs/testlog4cpp.log");
log4cpp::Appender* app2 = new
log4cpp::OstreamAppender("OstreamAppender",
&std::cerr);

// 2. Instantiate a layout object
// Two layouts come already available in log4cpp
// unless you create your own.
// BasicLayout includes a time stamp
log4cpp::Layout* layout =
new log4cpp::BasicLayout();

// 3. attach the layout object to the
// appender object
app->setLayout(layout);
app2->setLayout(layout);

// 4. Instantiate the category object
// you may extract the root category, but it is
// usually more practical to directly instance
// a child category
log4cpp::Category& main_cat =
log4cpp::Category::getInstance("main_cat");
log4cpp::Category& debug_cat =
log4cpp::Category::getInstance("debug_cat");

// 5. Step 1
// an Appender when added to a category becomes
// an additional output destination unless
// Additivity is set to false when it is false,
// the appender added to the category replaces
// all previously existing appenders
main_cat.setAdditivity(false);
debug_cat.setAdditivity(false);

// 5. Step 2
// this appender becomes the only one
main_cat.setAppender(app);
debug_cat.setAppender(app2);

// 6. Set up the priority for the category
// and is given INFO priority
// attempts to log DEBUG messages will fail
main_cat.setPriority(log4cpp::Priority::INFO);
debug_cat.setPriority(log4cpp::Priority::DEBUG);

// so we log some examples
main_cat.info("This is some info");
main_cat.debug("This debug message will fail to
write");
main_cat.alert("All hands abandon ship");
debug_cat.debug("This debug message will fail
to write");

// you can log by using a log() method with
// a priority
main_cat.log(log4cpp::Priority::WARN, "This
will be a logged warning");

// gives you some programmatic control over
// priority levels
log4cpp::Priority::PriorityLevel priority;
bool this_is_critical = true;
if(this_is_critical)
priority = log4cpp::Priority::CRIT;
else
priority = log4cpp::Priority::DEBUG;

// this would not be logged if priority
// == DEBUG, because the category priority is
// set to INFO
main_cat.log(priority,"Importance depends on
context");

// You may also log by using stream style
// operations on
main_cat.critStream() << "This will show up <<
as " << 1
<< " critical message"
<<
log4cpp::CategoryStream::ENDLINE;
main_cat.emergStream() << "This will show up as "
<< 1 << " emergency message" <<
log4cpp::CategoryStream::ENDLINE;
debug_cat.debugStream() << "File " << __FILE__
<< " line "
<< __LINE__
<< ": This is a
streamed debug message"
<<
log4cpp::CategoryStream::ENDLINE;

// Stream operations can be used directly
// with the main object, but are
// preceded by the severity level
main_cat << log4cpp::Priority::ERROR
<< "And this will be an error"
<< log4cpp::CategoryStream::ENDLINE;

// This illustrates a small bug in version
// 2.5 of log4cpp
main_cat.debug("debug"); // this is correctly
// skipped
debug_cat.debug("debug");
main_cat.info("info");
main_cat.notice("notice");
main_cat.warn("warn");
main_cat.error("error");
main_cat.crit("crit"); // this prints ALERT
// main_cat : crit
main_cat.alert("alert");// this prints PANIC
// main_cat : alert
main_cat.emerg("emerg");// this prints UNKOWN
// main_cat : emerg

main_cat.debug("Shutting down");// this will
// be skipped
debug_cat.debug("Shutting down");

// clean up and flush all appenders
log4cpp::Category::shutdown();
std::cout << "After shutdown()" << std::endl;
return 0;
}

[Glenn Zickert]

Logged In: YES
user_id=735375

app and app2 are both setting the same layout object.
Because the appenders take ownership of the layout object,
each appender must have its own layout object. This
analysis was confirmed by adding:

log4cpp::Layout* dbLayout = new log4cpp::BasicLayout();
// and changing: app2->setLayout(layout); to
app2->setLayout(dbLayout);

I recommend closure of this problem report.