Error if connections_max_idle_ms not larger than request_timeout_msverify-timeouts-set-correctly

`connections_max_idle_ms` must always be larger than `request_timeout_ms`
to avoid potentially unexpected behavior.

Fix #1680.

2 files changed, 12 insertions, 4 deletions

diff --git a/kafka/consumer/group.py b/kafka/consumer/group.py
index 531c107..f521891 100644
--- a/kafka/consumer/group.py
+++ b/kafka/consumer/group.py
@@ -313,11 +313,15 @@ class KafkaConsumer(six.Iterator):
                         new_config, self.config['auto_offset_reset'])
             self.config['auto_offset_reset'] = new_config
 
+        connections_max_idle_ms = self.config['connections_max_idle_ms']
         request_timeout_ms = self.config['request_timeout_ms']
         fetch_max_wait_ms = self.config['fetch_max_wait_ms']
-        if request_timeout_ms <= fetch_max_wait_ms:
-            raise KafkaConfigurationError("Request timeout (%s) must be larger than fetch-max-wait-ms (%s)" %
-                                          (request_timeout_ms, fetch_max_wait_ms))
+        if not (fetch_max_wait_ms < request_timeout_ms < connections_max_idle_ms):
+            raise KafkaConfigurationError(
+                "connections_max_idle_ms ({}) must be larger than "
+                "request_timeout_ms ({}) which must be larger than "
+                "fetch_max_wait_ms ({})."
+                .format(connections_max_idle_ms, request_timeout_ms, fetch_max_wait_ms))
 
         metrics_tags = {'client-id': self.config['client_id']}
         metric_config = MetricConfig(samples=self.config['metrics_num_samples'],
diff --git a/test/test_consumer.py b/test/test_consumer.py
index 4ea01c8..0b0d708 100644
--- a/test/test_consumer.py
+++ b/test/test_consumer.py
@@ -15,12 +15,16 @@ from kafka.structs import (
 class TestKafkaConsumer:
     def test_session_timeout_larger_than_request_timeout_raises(self):
         with pytest.raises(KafkaConfigurationError):
-            KafkaConsumer(bootstrap_servers='localhost:9092', api_version=(0,9), group_id='foo', session_timeout_ms=60000, request_timeout_ms=40000)
+            KafkaConsumer(bootstrap_servers='localhost:9092', api_version=(0, 9), group_id='foo', session_timeout_ms=60000, request_timeout_ms=40000)
 
     def test_fetch_max_wait_larger_than_request_timeout_raises(self):
         with pytest.raises(KafkaConfigurationError):
             KafkaConsumer(bootstrap_servers='localhost:9092', fetch_max_wait_ms=41000, request_timeout_ms=40000)
 
+    def test_connections_max_idle_ms_smaller_than_request_timeout_raises(self):
+        with pytest.raises(KafkaConfigurationError):
+            KafkaConsumer(bootstrap_servers='localhost:9092', connections_max_idle_ms=69000, request_timeout_ms=40000)
+
     def test_subscription_copy(self):
         consumer = KafkaConsumer('foo', api_version=(0, 10))
         sub = consumer.subscription()