[GitHub] [pulsar] bry00 opened a new issue #5634: Python consumer does not accept receiver_queue_size=0

[GitBox]

bry00 opened a new issue #5634: Python consumer does not accept 
receiver_queue_size=0
URL: https://github.com/apache/pulsar/issues/5634
 
 
   **Describe the bug**
   Python client does not accept receiver queue size equal to 0, but according 
to 
[documentation](https://pulsar.apache.org/docs/v2.0.1-incubating/cookbooks/message-queue#client-configuration-changes):
   > If you’d like to have tight control over message dispatching across 
consumers, set the consumers’ receiver queue size very low (potentially even to 
0 if necessary).
   while other clients (e.g. C++ and Java clients) accept receiver queue size 
equal to 0 and work according to documentation.
   
   **To Reproduce**
   Steps to reproduce the behavior:
   1. Run the following Python code:
   
   ```python
   #!/usr/bin/env python3
   import sys
   import pulsar
   
   client = pulsar.Client('pulsar://localhost:6650')
   consumer = client.subscribe('abcd', subscription_name='xyz',
       consumer_type=pulsar.ConsumerType.Shared,
       receiver_queue_size=0)
   
   msg = consumer.receive()
   print("Received message: %s" % msg.data(), flush=True)
   
   consumer.acknowledge(msg)
   client.close()
   
   ```
   
   2. See error
   
   **Expected behavior**
   Python client consumer API (` client.subscribe`) should accept parameter 
`receiver_queue_size=0` as described in 
[documentation](https://pulsar.apache.org/docs/v2.0.1-incubating/cookbooks/message-queue#client-configuration-changes)
 and as function correctly for other clients (C++, Java).
   
   **Screenshots**
   
   ```console
   2019-11-12 15:11:57.331 INFO  Client:88 | Subscribing on Topic :abcd
   2019-11-12 15:11:57.331 INFO  ConnectionPool:72 | Created connection for 
pulsar://localhost:6650
   2019-11-12 15:11:57.333 INFO  ClientConnection:324 | [[::1]:51100 -> 
[::1]:6650] Connected to broker
   2019-11-12 15:11:57.398 INFO  HandlerBase:52 | 
[persistent://public/default/abcd, xyz, 0] Getting connection from pool
   2019-11-12 15:11:57.423 INFO  ConnectionPool:72 | Created connection for 
pulsar://cfc0ca6995fc:6650
   2019-11-12 15:11:57.424 INFO  ClientConnection:326 | [[::1]:51101 -> 
[::1]:6650] Connected to broker through proxy. Logical broker: 
pulsar://cfc0ca6995fc:6650
   2019-11-12 15:11:57.684 INFO  ConsumerImpl:170 | 
[persistent://public/default/abcd, xyz, 0] Created consumer on broker 
[[::1]:51101 -> [::1]:6650]
   2019-11-12 15:11:57.684 WARN  ConsumerImpl:631 | 
[persistent://public/default/abcd, xyz, 0] Can't use this function if the queue 
size is 0
   Traceback (most recent call last):
     File "tst.py", line 10, in <module>
       msg = consumer.receive()
     File "/python3.7/site-packages/pulsar/__init__.py", line 930, in receive
       msg = self._consumer.receive()
   Exception: Pulsar error: InvalidConfiguration
   ```
   
   **Desktop (please complete the following information):**
    - OS: macOS Catalina (v: 10.15.1)
   
   

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