我有一个 web 应用程序（Tomcat/Hibernate/DBCP 1.4），它运行对 MySQL 的查询，这对于特定的负载很有效，比如每秒 50 个查询。当我通过 HAProxy 路由相同的中等负载（仍然只使用一个数据库）时，我会失败，可能每 500 次查询就会失败。我的应用报告：
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 196,898 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago.
at sun.reflect.GeneratedConstructorAccessor210.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3567)
...
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3017) …