Add profiling for celery tasks

src/pretix/base/services/async.py

@@ -7,11 +7,38 @@ Usage:
     @task(base=TransactionAwareTask)
     def task_…():
 """
-from celery import Task
+import cProfile
+import os
+import random
+import time
+
+from django.conf import settings
 from django.db import transaction
 
+from pretix.celery import app
 
-class TransactionAwareTask(Task):
+
+class ProfiledTask(app.Task):
+    abstract = True
+
+    def __call__(self, *args, **kwargs):
+
+        if settings.PROFILING_RATE > 0 and random.random() < settings.PROFILING_RATE / 100:
+            profiler = cProfile.Profile()
+            profiler.enable()
+            starttime = time.time()
+            ret = super().__call__(*args, **kwargs)
+            profiler.disable()
+            tottime = time.time() - starttime
+            profiler.dump_stats(os.path.join(settings.PROFILE_DIR, '{time:.0f}_{tottime:.3f}_celery_{t}.pstat'.format(
+                t=self.name, tottime=tottime, time=time.time()
+            )))
+            return ret
+        else:
+            return super().__call__(*args, **kwargs)
+
+
+class TransactionAwareTask(ProfiledTask):
     """
     Task class which is aware of django db transactions and only executes tasks
     after transaction has been committed