Add a pid file to avoid running honcho multiple times

manage.py

@@ -13,6 +13,8 @@
 # OR WITHIN THE LOCAL FILE "LICENSE"
 #
 #
+import atexit
+import logging
 import os
 import sys
 
@@ -22,13 +24,14 @@ from sith.composer import start_composer, stop_composer
 from sith.settings import PROCFILE_RUNSERVER
 
 if __name__ == "__main__":
+    logging.basicConfig(encoding="utf-8", level=logging.INFO)
+
     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "sith.settings")
 
     from django.core.management import execute_from_command_line
 
     if os.environ.get(DJANGO_AUTORELOAD_ENV) is None and PROCFILE_RUNSERVER is not None:
         start_composer(PROCFILE_RUNSERVER)
+        _ = atexit.register(stop_composer)
 
     execute_from_command_line(sys.argv)
-
-    stop_composer()

sith/composer.py

@@ -1,26 +1,68 @@
-import os
+import logging
 import signal
 import subprocess
 import sys
 
 import psutil
 
-COMPOSER_PID = "COMPOSER_PID"
+from sith import settings
+
+
+def get_pid() -> int | None:
+    """Read the PID file to get the currently running composer if it exists"""
+    if not settings.COMPOSER_PID_PATH.exists():
+        return None
+    with open(settings.COMPOSER_PID_PATH, "r", encoding="utf8") as f:
+        return int(f.read())
+
+
+def write_pid(pid: int):
+    """Write currently running composer pid in PID file"""
+    if not settings.COMPOSER_PID_PATH.exists():
+        settings.COMPOSER_PID_PATH.parent.mkdir(parents=True, exist_ok=True)
+    with open(settings.COMPOSER_PID_PATH, "w", encoding="utf8") as f:
+        _ = f.write(str(pid))
+
+
+def delete_pid():
+    """Delete PID file for cleanup"""
+    settings.COMPOSER_PID_PATH.unlink(missing_ok=True)
+
+
+def is_composer_running() -> bool:
+    """Check if the process in the PID file is running"""
+    pid = get_pid()
+    if pid is None:
+        return False
+    try:
+        return psutil.Process(pid).is_running()
+    except psutil.NoSuchProcess:
+        return False
 
 
 def start_composer(procfile: str):
     """Starts the composer and stores the PID as an environment variable
     This allows for running smoothly with the django reloader
     """
+    if is_composer_running():
+        logging.info(f"Composer is already running with pid {get_pid()}")
+        logging.info(
+            f"If this is a mistake, please delete {settings.COMPOSER_PID_PATH} and restart the process"
+        )
+        return
     process = subprocess.Popen(
         [sys.executable, "-m", "honcho", "-f", procfile, "start"],
     )
-    os.environ[COMPOSER_PID] = str(process.pid)
+    write_pid(process.pid)
 
 
 def stop_composer():
     """Stops the composer if it was started before"""
-    if (pid := os.environ.get(COMPOSER_PID, None)) is not None:
-        process = psutil.Process(int(pid))
+    if is_composer_running():
+        process = psutil.Process(get_pid())
+        if process.parent() != psutil.Process():
+            logging.info("Currently running composer is controlled by another process")
+            return
         process.send_signal(signal.SIGTERM)
-        process.wait()
+        _ = process.wait()
+        delete_pid()

sith/pytest.py

@@ -1,3 +1,5 @@
+import atexit
+
 import pytest
 
 from .composer import start_composer, stop_composer
@@ -15,7 +17,4 @@ def pytest_load_initial_conftests(early_config, parser, args):
     """Hook that loads the composer before the pytest-django plugin"""
     if PROCFILE_PYTEST is not None:
         start_composer(PROCFILE_PYTEST)
-
-
-def pytest_unconfigure(config):
-    stop_composer()
+        _ = atexit.register(stop_composer)

sith/settings.py

@@ -56,6 +56,9 @@ BASE_DIR = Path(__file__).parent.parent.resolve()
 PROCFILE_RUNSERVER = env.str("PROCFILE_RUNSERVER", None)
 PROCFILE_PYTEST = env.str("PROCFILE_PYTEST", None)
 
+## File path used to avoid running the composer multiple times at the same time
+COMPOSER_PID_PATH = env.path("COMPOSER_PID_PATH", BASE_DIR / "composer.pid")
+
 # Quick-start development settings - unsuitable for production
 # See https://docs.djangoproject.com/en/1.8/howto/deployment/checklist/