Fix possible hang when "complete()" called twice and crashed thread

See #647. The initial fix didn't prevented "complete()" to hang
if it was called a second time.

loguru/_handler.py

@@ -72,6 +72,7 @@ def __init__(
         self._confirmation_lock = None
         self._owner_process_pid = None
         self._thread = None
+        self._is_thread_dead = None
 
         if self._is_formatter_dynamic:
             if self._colorize:
@@ -90,6 +91,7 @@ def __init__(
             self._confirmation_event = multiprocessing.Event()
             self._confirmation_lock = multiprocessing.Lock()
             self._owner_process_pid = os.getpid()
+            self._is_thread_dead = multiprocessing.Event()
             self._thread = Thread(
                 target=self._queued_writer, daemon=True, name="loguru-writer-%d" % self._id
             )
@@ -218,6 +220,8 @@ def complete_queue(self):
             return
 
         with self._confirmation_lock:
+            if self._is_thread_dead.is_set():
+                return
             self._queue.put(True)
             self._confirmation_event.wait()
             self._confirmation_event.clear()
@@ -292,6 +296,7 @@ def _queued_writer(self):
             except Exception:
                 with lock:
                     if not self._error_interceptor.should_catch():
+                        self._is_thread_dead.set()
                         self._confirmation_event.set()
                         raise
                     self._error_interceptor.print(None)
@@ -309,6 +314,7 @@ def _queued_writer(self):
                     self._sink.write(message)
                 except Exception:
                     if not self._error_interceptor.should_catch():
+                        self._is_thread_dead.set()
                         self._confirmation_event.set()
                         raise
                     self._error_interceptor.print(message.record)

tests/test_add_option_enqueue.py

@@ -179,6 +179,7 @@ def test_not_caught_exception_sink_write_then_complete(capsys):
     with default_threading_excepthook():
         logger.bind(fail=True).info("Bye bye...")
         logger.complete()
+        logger.complete()  # Called twice to ensure it's re-usable.
         logger.remove()
 
     out, err = capsys.readouterr()
@@ -194,6 +195,7 @@ def test_not_caught_exception_queue_get_then_complete(writer, capsys):
     with default_threading_excepthook():
         logger.bind(broken=NotUnpicklable()).info("Bye bye...")
         logger.complete()
+        logger.complete()
         logger.remove()
 
     out, err = capsys.readouterr()