HiKariCP数据库连接池

HiKariCP是数据库连接池的一个后起之秀，号称性能最好，可以完美地PK掉其他连接池

官网：https://github.com/brettwooldridge/HikariCP

Java 8 maven artifact:

    <dependency>
        <groupId>com.zaxxergroupId>
        <artifactId>HikariCPartifactId>
        <version>2.6.2version>
    dependency>

Java 9 Early Access maven artifact:

    <dependency>
        <groupId>com.zaxxergroupId>
        <artifactId>HikariCP-java9eaartifactId>
        <version>2.6.1version>
    dependency>

Java 7 maven artifact (maintenance mode):

    <dependency>
        <groupId>com.zaxxergroupId>
        <artifactId>HikariCP-java7artifactId>
        <version>2.4.12version>
    dependency>

Java 6 maven artifact (maintenance mode):

    <dependency>
        <groupId>com.zaxxergroupId>
        <artifactId>HikariCP-java6artifactId>
        <version>2.3.13version>
    dependency

Initialization

You can use the HikariConfig class like so1:

HikariConfig config = new HikariConfig();
config.setJdbcUrl("jdbc:mysql://localhost:3306/simpsons");
config.setUsername("bart");
config.setPassword("51mp50n");
config.addDataSourceProperty("cachePrepStmts", "true");
config.addDataSourceProperty("prepStmtCacheSize", "250");
config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");

HikariDataSource ds = new HikariDataSource(config);

 1 MySQL-specific example, do not copy verbatim.

or directly instantiate a HikariDataSource like so:

HikariDataSource ds = new HikariDataSource();
ds.setJdbcUrl("jdbc:mysql://localhost:3306/simpsons");
ds.setUsername("bart");
ds.setPassword("51mp50n");
...

or property file based:

// Examines both filesystem and classpath for .properties file
HikariConfig config = new HikariConfig("/some/path/hikari.properties");
HikariDataSource ds = new HikariDataSource(config);

Example property file:

dataSourceClassName=org.postgresql.ds.PGSimpleDataSource
dataSource.user=test
dataSource.password=test
dataSource.databaseName=mydb
dataSource.portNumber=5432
dataSource.serverName=localhost

or java.util.Properties based:

Properties props = new Properties();
props.setProperty("dataSourceClassName", "org.postgresql.ds.PGSimpleDataSource");
props.setProperty("dataSource.user", "test");
props.setProperty("dataSource.password", "test");
props.setProperty("dataSource.databaseName", "mydb");
props.put("dataSource.logWriter", new PrintWriter(System.out));

HikariConfig config = new HikariConfig(props);
HikariDataSource ds = new HikariDataSource(config);

There is also a System property available, hikaricp.configurationFile, that can be used to specify the location of a properties file. If you intend to use this option, construct a HikariConfig or HikariDataSource instance using the default constructor and the properties file will be loaded.

Spring配置文件

HikariCP所做的一些优化，总结如下：

• 字节码精简：优化代码，直到编译后的字节码最少，这样，CPU缓存可以加载更多的程序代码；
• 优化代理和拦截器：减少代码，例如HikariCP的Statement proxy只有100行代码，只有BoneCP的十分之一；
• 自定义数组类型（FastStatementList）代替ArrayList：避免每次get()调用都要进行range check，避免调用remove()时的从头到尾的扫描；
• 自定义集合类型（ConcurrentBag）：提高并发读写的效率；
• 其他针对BoneCP缺陷的优化，比如对于耗时超过一个CPU时间片的方法调用的研究（但没说具体怎么优化）。