[MXS-2311] connection_keepalive and error : (4852) Unexpected internal state: received response 0x00 from server Created: 2019-01-31  Updated: 2020-08-25  Resolved: 2019-02-08

Status: Closed
Project: MariaDB MaxScale
Component/s: Protocol
Affects Version/s: 2.2.19, 2.3.3
Fix Version/s: 2.2.20, 2.3.4

Type: Bug Priority: Major
Reporter: Chris Calender (Inactive) Assignee: markus makela
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MXS-2461 Unexpected internal state with ReadWr... Closed
Sprint: MXS-SPRINT-75

 Description   

We saw the following error logged in MaxScale 2.3.3:

error : (4852) Unexpected internal state: received response 0x00 from server 'mariadb-server' when no response was expected. Command: 0x03 Query: <not available>

As I understand it, this should not have any negative side effects, but it seems to indicate a problem with the connection_keepalive ping mechanism.

A potential work-around/solution to avoid this to set the value of `connection_timeout` to a value close to `wait_timeout` to hopefully reduce the chance of logging these warnings.



 Comments   
Comment by markus makela [ 2019-02-08 ]

This was caused by the connection_keepalive parameter and a very slow master server. If the master was too slow to respond between pings or the ping could not be written fast enough, one ping would account for multiple pings resulting in unexpected responses.

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