Start pyroscope only after uwsgi fork (#1607)

# What this PR does
Currently main uwsgi process sends spans while being idle, which make
graphs unreadable
<img width="494" alt="Screenshot 2023-03-23 at 18 00 21"
src="https://user-images.githubusercontent.com/2262529/227168746-125f2329-bfaa-4989-a391-712a230e0087.png">

## Which issue(s) this PR fixes

## Checklist

- [ ] Tests updated
- [ ] Documentation added
- [ ] `CHANGELOG.md` updated

engine/engine/wsgi.py

@@ -40,3 +40,22 @@ if settings.OTEL_TRACING_ENABLED and settings.OTEL_EXPORTER_OTLP_ENDPOINT:
     except ModuleNotFoundError:
         # Only works under uwsgi web server environment
         pass
+
+if settings.PYROSCOPE_PROFILER_ENABLED:
+    try:
+        import pyroscope
+        from uwsgidecorators import postfork
+
+        @postfork
+        def init_pyroscope():
+            pyroscope.configure(
+                application_name=settings.PYROSCOPE_APPLICATION_NAME,
+                server_address=settings.PYROSCOPE_SERVER_ADDRESS,
+                auth_token=settings.PYROSCOPE_AUTH_TOKEN,
+                detect_subprocesses=True,
+                tags={"celery_worker": settings.PYROSCOPE_CELERY_WORKER_QUEUE},
+            )
+
+    except ModuleNotFoundError:
+        # Only works under uwsgi web server environment
+        pass

engine/settings/base.py

@@ -678,15 +678,7 @@ MIGRATION_LINTER_OPTIONS = {"exclude_apps": ["social_django", "silk", "fcm_djang
 MIGRATION_LINTER_OVERRIDE_MAKEMIGRATIONS = True
 
 PYROSCOPE_PROFILER_ENABLED = getenv_boolean("PYROSCOPE_PROFILER_ENABLED", default=False)
-if PYROSCOPE_PROFILER_ENABLED:
-    import pyroscope
-
-    pyroscope.configure(
-        application_name=os.getenv("PYROSCOPE_APPLICATION_NAME", "oncall"),
-        server_address=os.getenv("PYROSCOPE_SERVER_ADDRESS", "http://pyroscope:4040"),
-        auth_token=os.getenv("PYROSCOPE_AUTH_TOKEN", ""),
-        detect_subprocesses=True,
-        tags={
-            "celery_worker": os.getenv("CELERY_WORKER_QUEUE", None),
-        },
-    )
+PYROSCOPE_APPLICATION_NAME = os.getenv("PYROSCOPE_APPLICATION_NAME", "oncall")
+PYROSCOPE_SERVER_ADDRESS = os.getenv("PYROSCOPE_SERVER_ADDRESS", "http://pyroscope:4040")
+PYROSCOPE_AUTH_TOKEN = os.getenv("PYROSCOPE_AUTH_TOKEN", "")
+PYROSCOPE_CELERY_WORKER_QUEUE = os.getenv("CELERY_WORKER_QUEUE", None)