feat: configurable limit of simultaneous connections (python/asyncio) (#3200)

* feat: configurable limit of simultaneous connections (python/asyncio)

* fix: remove unused import (python/asyncio)

modules/openapi-generator/src/main/resources/python/asyncio/rest.mustache

@@ -38,8 +38,11 @@ class RESTResponse(io.IOBase):
 
 class RESTClientObject(object):
 
-    def __init__(self, configuration, pools_size=4, maxsize=4):
+    def __init__(self, configuration, pools_size=4, maxsize=None):
+
         # maxsize is number of requests to host that are allowed in parallel
+        if maxsize is None:
+            maxsize = configuration.connection_pool_maxsize
 
         # ca_certs
         if configuration.ssl_ca_cert:

modules/openapi-generator/src/main/resources/python/configuration.mustache

@@ -6,7 +6,9 @@ from __future__ import absolute_import
 
 import copy
 import logging
+{{^asyncio}}
 import multiprocessing
+{{/asyncio}}
 import sys
 import urllib3
 
@@ -116,6 +118,13 @@ class Configuration(six.with_metaclass(TypeWithDefault, object)):
         """Set this to True/False to enable/disable SSL hostname verification.
         """
 
+        {{#asyncio}}
+        self.connection_pool_maxsize = 100
+        """This value is passed to the aiohttp to limit simultaneous connections.
+           Default values is 100, None means no-limit.
+        """
+        {{/asyncio}}
+        {{^asyncio}}
         self.connection_pool_maxsize = multiprocessing.cpu_count() * 5
         """urllib3 connection pool's maximum number of connections saved
            per pool. urllib3 uses 1 connection as default value, but this is
@@ -123,6 +132,7 @@ class Configuration(six.with_metaclass(TypeWithDefault, object)):
            requests to the same host, which is often the case here.
            cpu_count * 5 is used as default value to increase performance.
         """
+        {{/asyncio}}
 
         self.proxy = None
         """Proxy URL

samples/client/petstore/python-asyncio/petstore_api/configuration.py

@@ -14,7 +14,6 @@ from __future__ import absolute_import
 
 import copy
 import logging
-import multiprocessing
 import sys
 import urllib3
 
@@ -115,12 +114,9 @@ class Configuration(six.with_metaclass(TypeWithDefault, object)):
         """Set this to True/False to enable/disable SSL hostname verification.
         """
 
-        self.connection_pool_maxsize = multiprocessing.cpu_count() * 5
+        self.connection_pool_maxsize = 100
-        """urllib3 connection pool's maximum number of connections saved
+        """This value is passed to the aiohttp to limit simultaneous connections.
-           per pool. urllib3 uses 1 connection as default value, but this is
+           Default values is 100, None means no-limit.
-           not the best value when you are making a lot of possibly parallel
-           requests to the same host, which is often the case here.
-           cpu_count * 5 is used as default value to increase performance.
         """
 
         self.proxy = None

samples/client/petstore/python-asyncio/petstore_api/rest.py

@@ -46,8 +46,11 @@ class RESTResponse(io.IOBase):
 
 class RESTClientObject(object):
 
-    def __init__(self, configuration, pools_size=4, maxsize=4):
+    def __init__(self, configuration, pools_size=4, maxsize=None):
+
         # maxsize is number of requests to host that are allowed in parallel
+        if maxsize is None:
+            maxsize = configuration.connection_pool_maxsize
 
         # ca_certs
         if configuration.ssl_ca_cert: