Merge pull request #505 from HackSoftware/blog/celery-non-concurrent-tasks

Blog example: Non-concurrent Celery task

Author: RadoRado

styleguide_example/blog_examples/celery_non_concurrent/tasks.py

@@ -0,0 +1,48 @@
+import logging
+from functools import wraps
+
+from celery import shared_task
+
+from styleguide_example.tasks import celery_app
+
+inspect = celery_app.control.inspect
+
+logger = logging.getLogger(__name__)
+
+
+def non_concurrent_task(_func=None, *args, **kwargs):
+    def wrapper(func):
+        @wraps(func)
+        def inner(_bound_self, *_func_args, **_func_kwargs):
+            running_task_count = 0
+
+            queues = inspect().active()
+
+            if queues is None:
+                queues = {}
+
+            for running_tasks in queues.values():
+                for task in running_tasks:
+                    if task["name"] == _bound_self.name:
+                        running_task_count += 1
+
+                    if running_task_count > 1:
+                        logger.warning(f"[non_concurrent_task] Task {_bound_self.name} is already running")
+                        return
+
+            return func(*_func_args, **_func_kwargs)
+
+        return shared_task(bind=True, *args, **kwargs)(inner)
+
+    if _func is None:
+        return wrapper
+
+    return wrapper(_func)
+
+
+@non_concurrent_task
+def test_non_concurrent_task():
+    logger.info("A non-concurrent task is running")
+    import time
+    time.sleep(10)
+    logger.info("A non-concurrent task finished")

styleguide_example/blog_examples/tasks.py

@@ -0,0 +1,2 @@
+# ruff: noqa
+from styleguide_example.blog_examples.celery_non_concurrent.tasks import test_non_concurrent_task