Druid连接池优化，TPS提升50%

概述

对Nginx域名转发做了个压测，结果不大理想，jmeter哗哗的报错，Nginx连接全是超时，tps波动剧烈，如下图

tps在490的时候开始剧烈抖动

大致的错误信息如下

{ : "timestamp":"2021-09-22T07:52:22.178+0000", : "status":500, : "error":"Internal Server Error", : "message":"\n### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure\n\nThe last packet successfully received from the server was 10,949 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago.\n### The error may exist in class path resource [mybatis/mapper/UserMapper.xml]\n### The error may involve defaultParameterMap\n### The error occurred while setting parameters\n### SQL: SELECT user_id,user_name,user_nickname,user_password,user_realname,user_gender,user_birthday,user_profile_picture_src,user_address,user_homeplace FROM user WHERE user_name = ? and user_password = ?\n### Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure\n\nThe last packet successfully received from the server was 10,949 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago.\n; Communications link failure\n\nThe last packet successfully received from the server was 10,949 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago.; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure\n\nThe last packet successfully received from the server was 10,949 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago.", : "path":"/tmall/login/doLogin" }

看错误信息是因为jdbc连接池异常中断导致的，检查一下连接池的配置

考虑到系统使用的人很少，几乎不会有多少jdbc并发，所以连接池的最大连接数有点高了，可能会资源浪费。改小一点再做调试

spring.datasource.druid.initial-size=3

spring.datasource.druid.min-idle=3

spring.datasource.druid.max-active=10

Tps基本保持稳定，jmeter不再报错。但是偶尔还是会有波动

linux能看到一些错误信息，如下

The last packet successfully received from the server was 11,938 milliseconds ago. The last packet sent successfully to the server was 1 milliseconds ago.; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure


The last packet successfully received from the server was 11,938 milliseconds ago. The last packet sent successfully to the server was 1 milliseconds ago.] with root cause 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:3014) ~[mysql-connector-java-5.1.47.jar:5.1.47] at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3472) ~[mysql-connector-java-5.1.47.jar:5.1.47] at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3462) ~[mysql-connector-java-5.1.47.jar:5.1.47] at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3905) ~[mysql-connector-java-5.1.47.jar:5.1.47] at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2530) ~[mysql-connector-java-5.1.47.jar:5.1.47] at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2683) ~[mysql-connector-java-5.1.47.jar:5.1.47] at

调用login方法的时候，mysql的IO队列阻塞了，数据包回不来。直接检查login调用的user表，看索引。这张表里面对username加了索引，但是没有对password加，也没对realname加。实际上登录执行的是realname字段！