Hang inside call to PoolManager request

dummyserver/handlers.py

@@ -106,7 +106,11 @@ def _call_method(self):
 
     def index(self, _request):
         "Render simple message"
-        return Response("Dummy server!")
+        data = "Dummy server!"
+        if "page" in _request.arguments:
+            page = _request.arguments["page"][0]
+            data += " page %s" % page.decode()
+        return Response(data)
 
     def certificate(self, request):
         """Return the requester's certificate."""

src/urllib3/connectionpool.py

@@ -36,7 +36,7 @@
     BaseSSLError,
 )
 from .request import RequestMethods
-from .response import HTTPResponse
+from .response import HTTPResponse, drain_conn
 
 from .util.connection import is_connection_dropped
 from .util.request import set_file_position
@@ -765,21 +765,6 @@ def urlopen(
                 **response_kw
             )
 
-        def drain_and_release_conn(response):
-            try:
-                # discard any remaining response body, the connection will be
-                # released back to the pool once the entire response is read
-                response.read()
-            except (
-                TimeoutError,
-                HTTPException,
-                SocketError,
-                ProtocolError,
-                BaseSSLError,
-                SSLError,
-            ):
-                pass
-
         # Handle redirect?
         redirect_location = redirect and response.get_redirect_location()
         if redirect_location:
@@ -790,15 +775,11 @@ def drain_and_release_conn(response):
                 retries = retries.increment(method, url, response=response, _pool=self)
             except MaxRetryError:
                 if retries.raise_on_redirect:
-                    # Drain and release the connection for this response, since
-                    # we're not returning it to be released manually.
-                    drain_and_release_conn(response)
+                    drain_conn(response)
                     raise
                 return response
 
-            # drain and return the connection to the pool before recursing
-            drain_and_release_conn(response)
-
+            drain_conn(response)
             retries.sleep_for_retry(response)
             log.debug("Redirecting %s -> %s", url, redirect_location)
             return self.urlopen(
@@ -824,15 +805,11 @@ def drain_and_release_conn(response):
                 retries = retries.increment(method, url, response=response, _pool=self)
             except MaxRetryError:
                 if retries.raise_on_status:
-                    # Drain and release the connection for this response, since
-                    # we're not returning it to be released manually.
-                    drain_and_release_conn(response)
+                    drain_conn(response)
                     raise
                 return response
 
-            # drain and return the connection to the pool before recursing
-            drain_and_release_conn(response)
-
+            drain_conn(response)
             retries.sleep(response)
             log.debug("Retry: %s", url)
             return self.urlopen(

src/urllib3/poolmanager.py

@@ -7,6 +7,7 @@
 from ._collections import RecentlyUsedContainer
 from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool
 from .connectionpool import port_by_scheme
+
 from .exceptions import (
     HTTPWarning,
     LocationValueError,
@@ -17,6 +18,7 @@
 from .packages import six
 from .packages.six.moves.urllib.parse import urljoin
 from .request import RequestMethods
+from .response import drain_conn
 from .util.url import parse_url
 from .util.retry import Retry
 
@@ -384,13 +386,16 @@ def urlopen(self, method, url, redirect=True, **kw):
             retries = retries.increment(method, url, response=response, _pool=conn)
         except MaxRetryError:
             if retries.raise_on_redirect:
+                drain_conn(response)
                 raise
             return response
 
         kw["retries"] = retries
         kw["redirect"] = redirect
 
         log.info("Redirecting %s -> %s", url, redirect_location)
+
+        drain_conn(response)
         return self.urlopen(method, redirect_location, **kw)
 
 

src/urllib3/response.py

@@ -20,6 +20,7 @@
     ResponseNotChunked,
     IncompleteRead,
     InvalidHeader,
+    HTTPError,
 )
 from .packages.six import string_types as basestring, PY3
 from .packages.six.moves import http_client as httplib
@@ -29,6 +30,17 @@
 log = logging.getLogger(__name__)
 
 
+def drain_conn(response):
+    """
+    Read and discard any remaining HTTP response data from the connection.
+    Unread data in the HTTPResponse connection blocks the connection from being released back to the pool
+    """
+    try:
+        response.read()
+    except (HTTPError, SocketError, BaseSSLError, HTTPException):
+        pass
+
+
 class DeflateDecoder(object):
     def __init__(self):
         self._first_try = True

test/with_dummyserver/test_poolmanager.py

@@ -22,6 +22,27 @@ def setup_class(cls):
         cls.base_url = "http://%s:%d" % (cls.host, cls.port)
         cls.base_url_alt = "http://%s:%d" % (cls.host_alt, cls.port)
 
+    def test_redirect_preload(self):
+        def build_request(number, preload):
+            return http.request(
+                "GET",
+                "%s/redirect" % self.base_url,
+                fields={"target": "%s/?page=%d" % (self.base_url, number)},
+                preload_content=preload,
+            )
+
+        with PoolManager(block=True, maxsize=3) as http:
+            for j in range(1, 5):
+                r1 = build_request(number=j, preload=True)
+                r2 = build_request(number=j, preload=False)
+
+                data = b"Dummy server! page %d" % j
+                assert r1.status == 200
+                assert r2.status == 200
+                assert r1.data == data
+                assert r2.data == data
+                r2.release_conn()  # Only need to release for preload=False
+
     def test_redirect(self):
         with PoolManager() as http:
             r = http.request(