Avoid 100% CPU usage while socket is closed

.travis.yml

@@ -6,6 +6,7 @@ python:
     - 2.7
     - 3.4
     - 3.7
+    - 3.8
     - pypy2.7-6.0
 
 env:

docs/compatibility.rst

@@ -16,6 +16,6 @@ Although kafka-python is tested and expected to work on recent broker versions,
 not all features are supported. Specifically, authentication codecs, and
 transactional producer/consumer support are not fully implemented. PRs welcome!
 
-kafka-python is tested on python 2.7, 3.4, 3.7, and pypy2.7.
+kafka-python is tested on python 2.7, 3.4, 3.7, 3.8 and pypy2.7.
 
 Builds and tests via Travis-CI.  See https://travis-ci.org/dpkp/kafka-python

kafka/client_async.py

@@ -635,6 +635,9 @@ def _poll(self, timeout):
             self._sensors.select_time.record((end_select - start_select) * 1000000000)
 
         for key, events in ready:
+            if key.fileobj.fileno() < 0:
+                self._selector.unregister(key.fileobj)
+
             if key.fileobj is self._wake_r:
                 self._clear_wake_fd()
                 continue

requirements-dev.txt

@@ -1,6 +1,6 @@
 flake8==3.4.1
-pytest==3.10.0
-pytest-cov==2.6.0
+pytest==5.4.3
+pytest-cov==2.10.0
 docker-py==1.10.6
 coveralls==1.5.1
 Sphinx==1.6.4
@@ -9,8 +9,8 @@ xxhash==1.3.0
 python-snappy==0.5.3
 tox==3.5.3
 mock==3.0.5
-pylint==1.9.3
-pytest-pylint==0.12.3
+pylint==2.5.3
+pytest-pylint==0.17.0
 pytest-mock==1.10.0
 sphinx-rtd-theme==0.2.4
 crc32c==1.7

setup.py

@@ -56,6 +56,7 @@ def run(cls):
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: Implementation :: PyPy",
         "Topic :: Software Development :: Libraries :: Python Modules",
     ]

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py{26,27,34,35,36,37,py}, docs
+envlist = py{26,27,34,35,36,37,38,py}, docs
 
 [pytest]
 testpaths = kafka test
@@ -8,10 +8,10 @@ log_format = %(created)f %(filename)-23s %(threadName)s %(message)s
 
 [testenv]
 deps =
-    pytest<4.0
+    pytest
     pytest-cov
-    py{27,34,35,36,37,py}: pylint
-    py{27,34,35,36,37,py}: pytest-pylint
+    py{27,34,35,36,37,38,py}: pylint
+    py{27,34,35,36,37,38,py}: pytest-pylint
     pytest-mock
     mock
     python-snappy