java HikariCP 连接池立即创建 100 个连接
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HikariCP Connection Pool immediately creates 100 connections
提问by Peter Andersson
I have this code that uses HikariCP Connection Pool:
我有这个使用 HikariCP 连接池的代码：
config.setMaximumPoolSize(100);
config.setDataSourceClassName("com.mysql.jdbc.jdbc2.optional.MysqlDataSource");
config.addDataSourceProperty("serverName", hostname);
config.addDataSourceProperty("port", portnumber);
config.addDataSourceProperty("databaseName", dbname);
config.addDataSourceProperty("user", username);
config.addDataSourceProperty("password", password);
config.setConnectionTimeout(30000);
config.setInitializationFailFast(false);
pooledDataSource = new HikariDataSource(config);
I monitor connections in mysql by issuing command "Show Processlist" and I see that 100 connections is created after line:
我通过发出命令“Show Processlist”来监视 mysql 中的连接，我看到在行之后创建了 100 个连接：
pooledDataSource = new HikariDataSource(config);
...is run. I'm sure this is not meant to happen, right? It should create connections later when I do pooledDataSource.getConnection().
...正在运行。我确定这不会发生，对吧？当我执行 pooledDataSource.getConnection() 时，它应该稍后创建连接。
What am I doing wrong? Why is it creating 100 connections immediately??
我究竟做错了什么？为什么它会立即创建 100 个连接？
回答by brettw
By default HikariCP runs as a fixed-sized pool. You need to set minimumIdle. That's it.
默认情况下，HikariCP 作为固定大小的池运行。您需要设置minimumIdle. 而已。
From the documentation for minimumIdle:
从文档中minimumIdle：
This property controls the minimum number of idle connections that HikariCP tries to maintain in the pool. If the idle connections dip below this value, HikariCP will make a best effort to add additional connections quickly and efficiently. However, for maximum performance and responsiveness to spike demands, we recommend not setting this value and instead allowing HikariCP to act as a fixed size connection pool. Default: same as maximumPoolSize
此属性控制 HikariCP 尝试在池中维护的最小空闲连接数。如果空闲连接低于此值，HikariCP 将尽最大努力快速有效地添加其他连接。但是，为了获得最佳性能和对峰值需求的响应，我们建议不要设置此值，而是允许 HikariCP 充当固定大小的连接池。默认值：与maximumPoolSize 相同
