Check timeout type in KafkaClient constructor

If a future was passed as the only positional parameter it would
be assigned to the "timeout_ms" parameter erroneously. This mistake
would not raise any exception but would lead to odd behaviour later,
what could make it extremely difficult to troubleshoot.

Adding a type check ensures that an exception is raise earlier to
notify the user about the problem.

1 files changed, 2 insertions, 0 deletions

diff --git a/kafka/client_async.py b/kafka/client_async.py
index 24a5bef..58155b8 100644
--- a/kafka/client_async.py
+++ b/kafka/client_async.py
@@ -545,6 +545,8 @@ class KafkaClient(object):
             timeout_ms = 100
         elif timeout_ms is None:
             timeout_ms = self.config['request_timeout_ms']
+        elif not isinstance(timeout_ms, (int, float)):
+            raise RuntimeError('Invalid type for timeout: %s' % type(timeout_ms))
 
         # Loop for futures, break after first loop if None
         responses = []