Close unclosed ports (#388)

pynecone/pc.py

@@ -87,10 +87,14 @@ def run(
     assert frontend_cmd and backend_cmd, "Invalid env"
 
     # Run the frontend and backend.
-    if frontend:
+    try:
-        frontend_cmd(app.app, Path.cwd(), port)
+        if frontend:
-    if backend:
+            frontend_cmd(app.app, Path.cwd(), port)
-        backend_cmd(app.__name__, loglevel=loglevel)
+        if backend:
+            backend_cmd(app.__name__, loglevel=loglevel)
+    finally:
+        utils.kill_process_on_port(os.environ["PORT"])
+        utils.kill_process_on_port(utils.get_api_port())
 
 
 @cli.command()

pynecone/utils.py

@@ -30,7 +30,7 @@ from typing import (
     Union,
 )
 from urllib.parse import urlparse
-
+import psutil
 import plotly.graph_objects as go
 import typer
 import uvicorn
@@ -582,6 +582,22 @@ def get_api_port() -> int:
     return port
 
 
+def kill_process_on_port(port):
+    """Kill the process on the given port.
+
+    Args:
+        port: The port.
+    """
+    for proc in psutil.process_iter(["pid", "name", "cmdline"]):
+        try:
+            for conns in proc.connections(kind="inet"):
+                if conns.laddr.port == port:
+                    proc.kill()
+                    return
+        except (psutil.NoSuchProcess, psutil.AccessDenied, psutil.ZombieProcess):
+            pass
+
+
 def run_backend(app_name: str, loglevel: constants.LogLevel = constants.LogLevel.ERROR):
     """Run the backend.