[PR] CASSANDRA-21539: Remove hostname from ClientsTable and GossipInfoTable to avoid reverse-DNS lookups (4.0) [cassandra]

["nivykani (via GitHub)" <gi...@apache.org>]

nivykani opened a new pull request, #4989:
URL: https://github.com/apache/cassandra/pull/4989

   The current code uses getHostName(), which has the known effect: This method may trigger a name service reverse lookup if the address was created with a literal IP address. This field in both ClientsTable and GossipInfoTable was constructed with addresses to begin with, not names, so getHostName() was always doing a blocking reverse-DNS lookup on row reads for the first call.
   
   This is a potentially slow blocking call, and we want to avoid doing any DNS lookups here because repeatedly querying this table could potentially overwhelm DNS, especially with frequently-changing client connections.
   
   We could instead use getHostName, but the primary key of both ClientsTable and GossipInfoTable is (address, port), where address is type inet. Thus, this field is redundant.
   
   To the best of my searching, no in-repo consumer depends on this column having a resolved name (and instead use an address-only path), and nodetool clientstats already doesn't display the hostname column.
   
   The [Cassandra Jira](https://issues.apache.org/jira/browse/CASSANDRA-21539)


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Re: [PR] CASSANDRA-21539: Remove hostname from ClientsTable and GossipInfoTable to avoid reverse-DNS lookups (4.0) [cassandra]

["smiklosovic (via GitHub)" <gi...@apache.org>]

smiklosovic closed pull request #4989: CASSANDRA-21539: Remove hostname from ClientsTable and GossipInfoTable to avoid reverse-DNS lookups (4.0)
URL: https://github.com/apache/cassandra/pull/4989


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