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Posted to commits@cassandra.apache.org by "João Reis (Jira)" <ji...@apache.org> on 2026/06/01 16:07:00 UTC
[jira] [Assigned] (CASSGO-125) Many "Pool connection error" with small Session.Timeout
[ https://issues.apache.org/jira/browse/CASSGO-125?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
João Reis reassigned CASSGO-125:
--------------------------------
Assignee: João Reis
> Many "Pool connection error" with small Session.Timeout
> -------------------------------------------------------
>
> Key: CASSGO-125
> URL: https://issues.apache.org/jira/browse/CASSGO-125
> Project: Apache Cassandra Go driver
> Issue Type: Bug
> Components: Core
> Reporter: João Reis
> Assignee: João Reis
> Priority: Normal
> Fix For: 2.1.2
>
>
> {quote}Version of driver: *v2.0.0* (latest)
> Go version: *1.24*
> Cassandra version: *5.0.4*
> If set global {{Session}} {{Timeout}} equal {{1*time.Second}} or less in logs we can see a lot of messages:
> {{"message":"Pool connection error.","addr":"10.239.171.143:9042","err":"read tcp 10.221.55.21:53299->10.229.171.143:9042: i/o timeout"}}
>
> The same thing happens with long timeouts, but less often.
> I tracked the full error flow:
> {{Conn.serve}} -> {{Conn.recv}} -> {{Conn.processFrame}} -> {{readHeader}} -> {{connReader.Read}} -> {{Conn.serve}} -> {{Conn.closeWithError}} ->{{{}hostConnPool.HandleError {}}}
> So the driver keeps getting read/timeout errors and closes the connection with error and establishes a new one (and so on all the time).
> The most surprising thing is that Cassandra's response time doesn't exceed 40ms at 99.9p. The go client isn't under any load.
> Also I've found, the Heartbeat connection is established with a general timeout, not a Connect timeout (which isn't entirely accurate). However, debugging has shown that this isn't the reason the connection is closed.
> Constant client-side reconnects put a strain on Cassandra.
> {quote}
> User report in [https://github.com/apache/cassandra-gocql-driver/issues/1919]
> We should get rid of the connection read deadline altogether. Maybe in a follow up ticket we can do a more comprehensive rework of the timeout settings (maybe add a readtimeout if someone really wants a read deadline for some reason).
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