MySQL Bugs: #115586: When upgrading to mysql connetor/j-8.4.0, creating a connection becomes too slow

Bug #115586	When upgrading to mysql connetor/j-8.4.0, creating a connection becomes too slow
Submitted:	15 Jul 2024 3:36	Modified:	6 Dec 2024 16:18
Reporter:	chen yi (OCA)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / J	Severity:	S1 (Critical)
Version:	8.4.0	OS:	Windows (windows 11)
Assigned to:		CPU Architecture:	x86 (13th Gen Intel(R) Core(TM) i7-13700H 2.40 GHz)
Tags:	slow

Description:
When upgrading to mysql connetor/j-8.4.0, creating a connection becomes too slow

use 8.3.0 create a connection about 10-100ms
use 8.4.0 create a connection more than 10s

mysql server version : mysql  Ver 8.0.35 for Linux on x86_64 (MySQL Community Server - GPL)

How to repeat:
		Driver driver = DriverManager.getDriver("jdbc:mysql:replication://192.168.1.233,192.168.1.233/PRICING?useUnicode=true&characterEncoding=utf8");
		Properties properties = new Properties();
		properties.put("user", "nextop");
		properties.put("password", "nextop");
		properties.put("tcpRcvBuf", "524288");
		properties.put("tcpSndBuf", "524288");
		properties.put("cachePrepStmts", "true");
		properties.put("prepStmtCacheSize", "128");
		properties.put("allowMultiQueries", "true");
		properties.put("maintainTimeStats", "false");
		properties.put("elideSetAutoCommits", "true");
		properties.put("useLocalSessionState", "true");
		properties.put("prepStmtCacheSqlLimit", "4096");
		properties.put("nullCatalogMeansCurrent", "true");
		properties.put("rewriteBatchedStatements", "true");
		properties.put("useOldAliasMetadataBehavior", "true");
		long st = System.currentTimeMillis();
		Connection connection = driver.connect("jdbc:mysql:replication://192.168.1.233,192.168.1.233/PRICING?useUnicode=true&characterEncoding=utf8", properties);
		connection.close();
		System.out.println(System.currentTimeMillis() - st);

The root cause is in ConnectionImpl L#458

this.connectionSpan.setAttribute(TelemetryAttribute.NETWORK_PEER_ADDRESS, inetSocketAddress.getHostName());

inetSocketAddress.getHostName() resolve host name too slow.

When we configured DNS reverse lookup, the time taken to create connections dropped to milliseconds. However, most of our internal mysql servers currently do not have reverse lookup configured.

Hello chen yi,

Thank you for the report and feedback.

regards,
Umesh

Bug #115736 marked as duplicate of this one

Posted by developer:
 
Added the following entry to the Connector/J 9.2.0 changelog: 

"It might take a long time to create a connection to a server with Connector/J 8.4.0 or later. It was because Connector/J 8.4.0 and later always performed a reverse DNS lookup on the host IP address. With this patch, the lookup is only performed when OpenTelemetry is used, in which case the lookup is required."