loop panic

code:

  struct LogEvent {
  std::string fmt;
  void *udata;
  std::string file_path;
  int line;
  SlogLevel level;
  std::string tag;
  int syslog_triger;

  explicit LogEvent(std::string fmt, void *udata, std::string file_path, int line, SlogLevel level, std::string tag,
                    int syslog_triger = 0)
      : fmt(std::move(fmt)),
        udata(udata),
        file_path(std::move(file_path)),
        line(line),
        level(level),
        tag(std::move(tag)),
        syslog_triger(syslog_triger) {}
};
  
 moodycamel::ConcurrentQueue<LogEvent> log_buffer_;
   static void LogToSyslog(const LogEvent &lev) {
    auto log_t = fmt::format("{}: {}", lev.tag, lev.fmt);
    syslog(LoggerTools::LevelSyslog(lev.level), "%s", log_t.c_str());
  } 
int main() {
   const LogEvent lev{
        formatted, nullptr, file, line, level, tag,
    };
  
    log_buffer_.enqueue(lev);
    while (log_buffer_.size_approx() > 0) {
    LogEvent lev{"", nullptr, "", 0, SlogLevel::DEBUG, ""};
    auto ret = log_buffer_.try_dequeue(lev);
    if (!ret) {
      continue;
    }
    if (lev.level >= default_level_) {
      LogToSyslog(lev);
    }
  }
}

panic info:

#0  std::__atomic_base<unsigned long>::load (__m=std::memory_order_relaxed, this=0x8c618a53ab61cf75) at /home/sinsegye/.conan/data/gcc/8.4.0/_/_/package/c36389a16c86a80fda9a30c45330b881d7951813/include/c++/8.4.0/bits/atomic_base.h:396
#1  moodycamel::ConcurrentQueue<slog::LogEvent, moodycamel::ConcurrentQueueDefaultTraits>::ProducerBase::size_approx (this=0x8c618a53ab61cf55) at /home/sinsegye/.conan/data/concurrentqueue/1.0.4/_/_/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9/include/moodycamel/concurrentqueue.h:1739
#2  0x000000000041721a in moodycamel::ConcurrentQueue<slog::LogEvent, moodycamel::ConcurrentQueueDefaultTraits>::size_approx (this=0x4a3860 <slog::Logger::instance()::inst>)
    at /home/sinsegye/.conan/data/concurrentqueue/1.0.4/_/_/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9/include/moodycamel/concurrentqueue.h:1329
#3  0x0000000000406b36 in slog::Logger::Worker (this=0x4a3860 <slog::Logger::instance()::inst>) at /home/sinsegye/workspace/apps/src/logger/logger.cc:75
#4  0x000000000041b54f in std::__invoke_impl<void, void (slog::Logger::*)(), slog::Logger*> (__f=@0x1397bd0: (void (slog::Logger::*)(slog::Logger * const)) 0x406acc <slog::Logger::Worker()>, __t=@0x1397bc8: 0x4a3860 <slog::Logger::instance()::inst>)
    at /home/sinsegye/.conan/data/gcc/8.4.0/_/_/package/c36389a16c86a80fda9a30c45330b881d7951813/include/c++/8.4.0/bits/invoke.h:73
#5  0x0000000000417a95 in std::__invoke<void (slog::Logger::*)(), slog::Logger*> (__fn=@0x1397bd0: (void (slog::Logger::*)(slog::Logger * const)) 0x406acc <slog::Logger::Worker()>)
    at /home/sinsegye/.conan/data/gcc/8.4.0/_/_/package/c36389a16c86a80fda9a30c45330b881d7951813/include/c++/8.4.0/bits/invoke.h:95
#6  0x000000000045ddae in std::thread::_Invoker<std::tuple<void (slog::Logger::*)(), slog::Logger*> >::_M_invoke<0ul, 1ul> (this=0x1397bc8) at /home/sinsegye/.conan/data/gcc/8.4.0/_/_/package/c36389a16c86a80fda9a30c45330b881d7951813/include/c++/8.4.0/thread:244
#7  0x000000000045d92e in std::thread::_Invoker<std::tuple<void (slog::Logger::*)(), slog::Logger*> >::operator() (this=0x1397bc8) at /home/sinsegye/.conan/data/gcc/8.4.0/_/_/package/c36389a16c86a80fda9a30c45330b881d7951813/include/c++/8.4.0/thread:253
#8  0x000000000045c50e in std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (slog::Logger::*)(), slog::Logger*> > >::_M_run (this=0x1397bc0) at /home/sinsegye/.conan/data/gcc/8.4.0/_/_/package/c36389a16c86a80fda9a30c45330b881d7951813/include/c++/8.4.0/thread:196
#9  0x00007ac349537253 in ?? () from /lib/x86_64-linux-gnu/libstdc++.so.6
#10 0x00007ac3491bfac3 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#11 0x00007ac349250a04 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:100

Start with the reported access in concurrentqueue.h at lines 1329 and 1739, then inspect the caller at logger.cc:75. Reproduce the enqueue and dequeue loop from the issue and determine why size_approx reaches invalid state. Done means the loop no longer panics under the reported usage, with a regression test covering the case.