I have a very weird issue with an older MySQL server (v5.0.45) and a Java application.
From time to time getting a connection from the database takes 7 seconds, 15 seconds, 30 seconds etc (most of them are 15 seconds) or sometimes times out. This happens just from time to time. I don't see a pattern when it does happen. The rest of the time connections are created in 2-3 milliseconds.
The database is running on Linux CentOS 6.4. The servers that have issues while connecting are on Linux CentOS 7. I'm using the latest MySQL connector (currently at v5.1.38), Java 8, with a connection pool (be it that of Tomcat or c3p0) or with no connection pool (just opening and closing connections), server in load or with few clients, a few simultaneous connections or up to 100 connections. It's the same result.
Multiple applications on multiple servers connect to this database. Only on two of them this occurs, the rest have no issues, the network seems fine, the other machines are in the same network.
- How can I debug this issue and find the cause?
- Has anyone seen this behaviour before?
EDIT: We've norrowed down the issue to the actual servers. Don't know if it's a hardware problem or an OS/kernel/drivers one. Still investigating.