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https://issues.apache.org/jira/browse/CASSANDRA-8086?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14345289#comment-14345289
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Joshua McKenzie commented on CASSANDRA-8086:
--------------------------------------------
It appears you've double-decremented on the connectionsPerClient record when
the IP's over the limit:
{code}
if (perIpCount.incrementAndGet() > perIpLimit)
{
perIpCount.decrementAndGet();
// The decrement will be done in channelClosed(...)
{code}
While counter is decremented in channelClosed and likely what that comment
refers to, you're also decrementing the connectionsPerClient record again for
the address in question.
Other than that, LGTM.
> Cassandra should have ability to limit the number of native connections
> -----------------------------------------------------------------------
>
> Key: CASSANDRA-8086
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8086
> Project: Cassandra
> Issue Type: Bug
> Reporter: Vishy Kasar
> Assignee: Norman Maurer
> Fix For: 2.1.4
>
> Attachments:
> 0001-CASSANDRA-8086-Allow-to-limit-the-number-of-native-c-2.0.patch,
> 0001-CASSANDRA-8086-Allow-to-limit-the-number-of-native-c-final.patch,
> 0001-CASSANDRA-8086-Allow-to-limit-the-number-of-native-c.patch,
> 0001-CASSANDRA-8086-Allow-to-limit-the-number-of-native-c.txt
>
>
> We have a production cluster with 72 instances spread across 2 DCs. We have a
> large number ( ~ 40,000 ) of clients hitting this cluster. Client normally
> connects to 4 cassandra instances. Some event (we think it is a schema change
> on server side) triggered the client to establish connections to all
> cassandra instances of local DC. This brought the server to its knees. The
> client connections failed and client attempted re-connections.
> Cassandra should protect itself from such attack from client. Do we have any
> knobs to control the number of max connections? If not, we need to add that
> knob.
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