CPU improvements + step() API

client/python/projectairsim/pyproject.toml

@@ -63,6 +63,10 @@ bonsai = [
 datacollection = [
   "albumentations==1.3.0",
 ]
+tests = [
+  "pytest",
+  "psutil>=5.9.0",
+]
 
 [tool.setuptools]
 # Source layout: packages live under src/

client/python/projectairsim/src/projectairsim/client.py

@@ -78,9 +78,6 @@ def connect(self):
             )
         projectairsim_log().info("Connection opened.")
         self.state = True
-        self.recv_topic_thread = threading.Thread(target=self.__recv_topic)
-        self.recv_topic_thread.start()
-        projectairsim_log().info("Started the pub-sub topic receiving thread.")
 
     def get_topic_info(self):
         """This is used by World to get the list of topic info on reload scene."""
@@ -125,6 +122,12 @@ def subscribe(self, topic, callback, reliability=1.0):
             topic (str): the name of the topic
             callback (callable): function to call when data is received
         """
+        # Lazily start the recv thread on first subscribe call
+        if self.recv_topic_thread is None:
+            self.socket_topics.recv_timeout = 100  # ms — bounded block for clean shutdown
+            self.recv_topic_thread = threading.Thread(target=self.__recv_topic)
+            self.recv_topic_thread.start()
+
         if topic in self.subs:
             self.subs[topic]["callbacks"].append(callback)
             self.subs[topic]["reliability"] = reliability
@@ -479,9 +482,10 @@ def __make_message_frame(self, topic, message):
 
     def __recv_topic_frame(self):
         try:
-            # Check if new data is ready to be received with non-blocking recv() call
-            frame_packed = self.socket_topics.recv(block=False)
-        except pynng.exceptions.TryAgain:
+            # Blocking recv with timeout (set on socket in subscribe()).
+            # Returns None on timeout so the loop can check self.state.
+            frame_packed = self.socket_topics.recv()
+        except (pynng.exceptions.TryAgain, pynng.exceptions.Timeout):
             return
 
         # If data was ready to be received, process and return it.

client/python/projectairsim/src/projectairsim/world.py

@@ -334,7 +334,34 @@ def continue_for_single_step(self, wait_until_complete: bool = True) -> int:
         single_step_result: str = self.client.request(single_step_req)
         return single_step_result
 
-    def list_actors(self) -> List[str]:
+    def step(self, dt_ns: int) -> dict:
+        """Advance sim by dt_ns nanoseconds and return bundled state + events.
+
+        This is the pull API entry point. The sim advances time, then returns
+        per-drone kinematics and any events (collisions) that
+        occurred during the step.
+
+        Actions should be sent to individual drones via their existing move
+        methods before calling step().
+
+        Args:
+            dt_ns: simulation time to advance, in nanoseconds
+
+        Returns:
+            dict with keys:
+                sim_time_ns (int): current sim time after the step
+                drones (dict): per-drone data keyed by drone ID, each containing:
+                    state (dict): position, orientation, linear_velocity, angular_velocity
+                    events (list): collision and gate_pass events with sim_time_ns ordering
+        """
+        step_req: dict = {
+            "method": f"{self.parent_topic}/Step",
+            "params": {"dt_ns": dt_ns},
+            "version": 1.0,
+        }
+        return self.client.request(step_req)
+
+    def list_actors(self) -> list[str]:
         """List actor names in the scene
 
         Returns: