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https://issues.apache.org/jira/browse/CASSANDRA-17411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17514118#comment-17514118
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Pere Balaguer commented on CASSANDRA-17411:
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Hey [~brandon.williams],
I am going to do a bit of an assumption with my comment, please correct me if
I'm wrong.
If you kept the app running for a few more minutes you should have seen other
"got x/y ... timeouts/total_rqs" where (x>0) entries, highlighting the client
still sends requests to the DOWN node which didn't happen in c3. In c3 after in
flight requests are concluded, no more traffic is sent to the DOWN node until
it goes back UP
This behavior (sending queries to a DOWN node) is specially bad when counters
are involved as those do not seem trigger speculative retries and always result
in query timeouts for the client.
> Network partition causes write ONE timeouts when using counters in Cassandra 4
> ------------------------------------------------------------------------------
>
> Key: CASSANDRA-17411
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17411
> Project: Cassandra
> Issue Type: Bug
> Components: Consistency/Coordination
> Reporter: Pere Balaguer
> Assignee: Brandon Williams
> Priority: Normal
> Fix For: 4.0.x
>
> Attachments: app.py
>
>
> h5. Affected versions:
> * 4.x
> h5. Observed behavior:
> When executing CL=ONE writes on a table with a counter column, if one of the
> nodes is network partitioned from the others, clients keep sending requests
> to it.
> Even though this may be a "driver" problem, I've been able to reproduce it
> with both java and python datastax drivers using their latest available
> versions and given the behavior only changes depending on the Cassandra
> version, well, here I am.
> h5. Expected behavior:
> In Cassandra 3 after all inflight requests fail (expected), no new requests
> are sent to the partitioned node. The expectation is that Cassandra 4 behaves
> the same way.
> h5. How to reproduce:
> {noformat}
> # Create a cluster with the desired version, will go with 4.x for this example
> ccm create bug-report -v 4.0.3
> ccm populate -n 2:2:2
> ccm start
> # Create schemas and so on
> CQL=$(cat <<END
> CONSISTENCY ALL;
> DROP KEYSPACE IF EXISTS demo;
> CREATE KEYSPACE demo WITH REPLICATION = {'class': 'NetworkTopologyStrategy',
> 'dc1': 2, 'dc2': 2, 'dc3': 2};
> CREATE TABLE demo.demo (pk uuid PRIMARY KEY, count counter) WITH compaction =
> {'class': 'LeveledCompactionStrategy'};
> END
> )
> ccm node1 cqlsh --verbose --exec="${CQL}"
> # Launch the attached app.py
> # requires cassandra-driver
> python3 app.py "127.0.0.1" "9042"
> # Wait a bit for the app to settle, proceed to next step once you see 3
> messages in stdout like:
> # 2022-03-01 15:41:51,557 - target-dc2 - __main__ - INFO - Got 0/572
> (0.000000) timeouts/total_rqs in the last 1 minute
> # Partition one node with iptables
> iptables -A INPUT -p tcp --destination 127.0.0.1 --destination-port 7000 -j
> DROP; iptables -A INPUT -p tcp --destination 127.0.0.1 --destination-port
> 9042 -j DROP
> {noformat}
> Some time after executing the iptables command in cassandra-3 the output
> should be similar to:
> {noformat}
> 2022-03-01 15:41:51,557 - target-dc2 - __main__ - INFO - Got 0/572 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:41:51,576 - target-dc3 - __main__ - INFO - Got 0/572 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:41:58,032 - target-dc1 - __main__ - INFO - Got 6/252 (2.380952)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:42:51,560 - target-dc2 - __main__ - INFO - Got 0/570 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:42:51,620 - target-dc3 - __main__ - INFO - Got 0/570 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:42:58,101 - target-dc1 - __main__ - INFO - Got 2/354 (0.564972)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:43:51,602 - target-dc2 - __main__ - INFO - Got 0/571 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:43:51,672 - target-dc3 - __main__ - INFO - Got 0/571 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:43:58,153 - target-dc1 - __main__ - INFO - Got 0/572 (0.000000)
> timeouts/total_rqs in the last 1 minute
> {noformat}
> as the timeouts/rqs shows, in about 2 minutes the partitioned node stops
> receiving traffic
> while as in cassandra-4
> {noformat}
> 2022-03-01 15:49:39,068 - target-dc3 - __main__ - INFO - Got 0/566 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:49:39,107 - target-dc2 - __main__ - INFO - Got 0/566 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:49:41,206 - target-dc1 - __main__ - INFO - Got 2/444 (0.450450)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:50:39,095 - target-dc3 - __main__ - INFO - Got 0/569 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:50:39,148 - target-dc2 - __main__ - INFO - Got 0/569 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:50:42,589 - target-dc1 - __main__ - INFO - Got 7/13 (53.846154)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:51:39,125 - target-dc3 - __main__ - INFO - Got 0/567 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:51:39,159 - target-dc2 - __main__ - INFO - Got 0/567 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:51:44,902 - target-dc1 - __main__ - INFO - Got 12/22
> (54.545455) timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:52:39,188 - target-dc2 - __main__ - INFO - Got 0/567 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:52:39,202 - target-dc3 - __main__ - INFO - Got 0/568 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:52:46,994 - target-dc1 - __main__ - INFO - Got 12/20
> (60.000000) timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:53:39,202 - target-dc2 - __main__ - INFO - Got 0/568 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:53:39,238 - target-dc3 - __main__ - INFO - Got 0/568 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:53:48,765 - target-dc1 - __main__ - INFO - Got 12/17
> (70.588235) timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:54:39,203 - target-dc2 - __main__ - INFO - Got 0/568 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:54:39,291 - target-dc3 - __main__ - INFO - Got 0/568 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:54:51,291 - target-dc1 - __main__ - INFO - Got 12/24
> (50.000000) timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:55:39,258 - target-dc2 - __main__ - INFO - Got 0/570 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:55:39,327 - target-dc3 - __main__ - INFO - Got 0/570 (0.000000)
> timeouts/total_rqs in the last 1 minute
> 2022-03-01 15:55:53,365 - target-dc1 - __main__ - INFO - Got 12/20
> (60.000000) timeouts/total_rqs in the last 1 minute
> {noformat}
> as the timeouts/rqs shows, the partitioned node keeps receving traffic until
> the iptables rules are removed
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