From dcb1f9a9e70a57a0466f749f9e8762965f210939 Mon Sep 17 00:00:00 2001
From: Min RK <benjaminrk@gmail.com>
Date: Wed, 11 Nov 2015 13:22:08 +0100
Subject: [PATCH] CurlAsyncHTTPClient: free_list starvation if setup fails

If `_curl_setup_request` fails,
the failing curl instance would be permanently excluded from free_list,
because `_finish` will never be called.
Once this has happens `max_clients` times,
no future request will ever complete.
---
 tornado/curl_httpclient.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tornado/curl_httpclient.py b/tornado/curl_httpclient.py
index 22f250232..6dadedd9f 100644
--- a/tornado/curl_httpclient.py
+++ b/tornado/curl_httpclient.py
@@ -221,6 +221,7 @@ class CurlAsyncHTTPClient(AsyncHTTPClient):
                         # _process_queue() is called from
                         # _finish_pending_requests the exceptions have
                         # nowhere to go.
+                        self._free_list.append(curl)
                         callback(HTTPResponse(
                             request=request,
                             code=599,
-- 
2.47.2