python-api_client.py.patch

--- a/kubernetes/client/api_client.py
+++ b/kubernetes/client/api_client.py
@@ -58,13 +58,15 @@ class ApiClient(object):
         'datetime': datetime,
         'object': object,
     }
+    _pool = None
 
-    def __init__(self, configuration=None, header_name=None, header_value=None, cookie=None):
+    def __init__(self, configuration=None, header_name=None, header_value=None,
+                 cookie=None, pool_threads=None):
         if configuration is None:
             configuration = Configuration()
         self.configuration = configuration
+        self.pool_threads = pool_threads
 
-        self.pool = ThreadPool()
         self.rest_client = RESTClientObject(configuration)
         self.default_headers = {}
         if header_name is not None:
@@ -74,8 +76,19 @@ class ApiClient(object):
         self.user_agent = 'Swagger-Codegen/8.0.0-snapshot/python'
     
     def __del__(self):
-        self.pool.close()
-        self.pool.join()
+        if self._pool:
+            self._pool.close()
+            self._pool.join()
+            self._pool = None
+
+    @property
+    def pool(self):
+        """Create thread pool on first request
+         avoids instantiating unused threadpool for blocking clients.
+        """
+        if self._pool is None:
+            self._pool = ThreadPool(self.pool_threads)
+        return self._pool
 
     @property
     def user_agent(self):