Don't init profile / meter damon threads when not active. (#295)

* only init profile / meter when active

Don't init profile / meter damon threads when not active, since thread is expensive in python.

* only profiling when active

Don't run profiling when config.agent_profile_active set to False.

Author: ZEALi

skywalking/agent/__init__.py

@@ -259,8 +259,10 @@ def start(self) -> None:
             import grpc.experimental.gevent as grpc_gevent
             grpc_gevent.init_gevent()
 
-        profile.init()
-        meter.init(force=True)  # force re-init after fork()
+        if config.agent_profile_active:
+            profile.init()
+        if config.agent_meter_reporter_active:
+            meter.init(force=True)  # force re-init after fork()
 
         self.__bootstrap()  # calls init_threading
 

skywalking/trace/context.py

@@ -149,7 +149,7 @@ def new_entry_span(self, op: str, carrier: Optional[Carrier] = None, inherit: Op
 
         parent = self.peek()
         # start profiling if profile_context is set
-        if self.profile_status is None:
+        if config.agent_profile_active and self.profile_status is None:
             self.profile_status = profile.profile_task_execution_service.add_profiling(self,
                                                                                        self.segment.segment_id,
                                                                                        op)
@@ -192,6 +192,8 @@ def new_exit_span(self, op: str, peer: str,
         return span
 
     def profiling_recheck(self, span: Span, op_name: str):
+        if not config.agent_profile_active:
+            return
         # only check first span, e.g, first opname is correct.
         if span.sid != 0:
             return