From a14fa5c51002d676f654945dbed6822336d17ff2 Mon Sep 17 00:00:00 2001
From: ninjaahhh <38544039+ninjaahhh@users.noreply.github.com>
Date: Thu, 6 Aug 2020 13:38:36 -0700
Subject: [PATCH] Use system available ports in cluster test (#915)

---
 quarkchain/cluster/tests/test_utils.py | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/quarkchain/cluster/tests/test_utils.py b/quarkchain/cluster/tests/test_utils.py
index af3b38e25..d52edf14f 100644
--- a/quarkchain/cluster/tests/test_utils.py
+++ b/quarkchain/cluster/tests/test_utils.py
@@ -1,6 +1,6 @@
 import asyncio
-import os
-from contextlib import ContextDecorator
+import socket
+from contextlib import ContextDecorator, closing
 
 from quarkchain.cluster.cluster_config import (
     ClusterConfig,
@@ -288,21 +288,11 @@ def get_shard_state(self, full_shard_id: int) -> ShardState:
         return shard.state
 
 
-# server.close() does not release the port sometimes even after server.wait_closed() is awaited.
-# we have to use unique ports for each test as a workaround.
-# also check if in CircleCI to avoid port collision
-if "CIRCLE_NODE_INDEX" in os.environ:
-    # max parallelism is 4
-    PORT_START = (int(os.environ["CIRCLE_NODE_INDEX"]) + 1) * 10000
-else:
-    PORT_START = 50000
-
-
 def get_next_port():
-    global PORT_START
-    port = PORT_START
-    PORT_START += 1
-    return port
+    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
+        s.bind(("", 0))
+        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        return s.getsockname()[1]
 
 
 def create_test_clusters(