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Django Server Hangs During Startup/Shutdown Due to Blocking LogtailHandler.flush() #35

@vikram-typeset

Description

@vikram-typeset

Problem

Django server hangs indefinitely during startup/shutdown when LogtailHandler is enabled. When commenting out the logtail configuration, the server works fine. This issue occurs consistently but not always - depends on timing and network conditions.

Root Cause

The LogtailHandler.flush() method blocks indefinitely in an infinite loop without timeout:

# logtail/flusher.py lines 80-84
def flush(self):
    self._flushing = True
    while not self._clean or not self.pipe.empty():
        time.sleep(self.check_interval)  # Infinite loop!
    self._flushing = False

Reproduction

  1. Add LogtailHandler to Django logging configuration
  2. Start Django server: python manage.py runserver
  3. Stop server with Ctrl+C
  4. Result: Server hangs and must be force-killed

Workaround: Commenting out logtail handler makes Django work normally.

Error When Force-Interrupted

Traceback (most recent call last):
  File "/usr/lib/python3.11/logging/__init__.py", line 2185, in shutdown
    h.flush()
  File "logtail/flusher.py", line 83, in flush
    time.sleep(self.check_interval)
KeyboardInterrupt:

Environment

  • Python 3.11, Django 3.2.8+, logtail 0.3.3

Proposed Fix

Add a flush_timeout parameter (default 5 seconds) to prevent infinite waiting:

def flush(self):
    self._flushing = True
    start_time = time.time()
    while not self._clean or not self.pipe.empty():
        if time.time() - start_time > self.flush_timeout:
            break  # Exit after timeout
        time.sleep(self.check_interval)
    self._flushing = False

Impact

  • Prevents graceful Django shutdown
  • Affects development workflow and deployment scripts
  • Forces developers to kill processes manually

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