前言
Springboot让Java开发更加美好，更加简洁，更加简单。Spring Boot 2.x中使用HikariCP作为默认的数据连接池。 HikariCP使用Javassist字节码操作库来实现动态代理，优化并精简了字节码，同时内部使用 com.zaxxer.hikari.util.FastList 代替ArrayList、使用了更好的并发集合类 com.zaxxer.hikari.util.ConcurrentBag ，“号称”是目前最快的数据库连接池。
下面话不多说了，来一起看看详细的介绍吧
基本使用
在Spring Boot 2.x中使用HikariCP十分简单，只需引入依赖 implementation 'org.springframework.boot:spring-boot-starter-jdbc' ：
pluginManagement {
repositories {
gradlePluginPortal()
}
}
rootProject.name = 'datasource-config'
plugins {
id 'org.springframework.boot' version '2.1.3.RELEASE'
id 'java'
}
apply plugin: 'io.spring.dependency-management'
group = 'spring-boot-guides'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'
repositories {
mavenCentral()
}
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-jdbc'
runtimeOnly 'com.h2database:h2'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
}
配置文件如下：
spring: datasource: url: jdbc:h2:mem:demodb username: sa password: hikari: # https://github.com/brettwooldridge/HikariCP (uses milliseconds for all time values) maximumPoolSize: 10 minimumIdle: 2 idleTimeout: 600000 connectionTimeout: 30000 maxLifetime: 1800000
关于连接池的具体配置参数详见 HikariCP 。
示例代码如下：
package springbootguides.datasourceconfig;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import javax.sql.DataSource;
import java.sql.Connection;
@SpringBootApplication
public class DatasourceConfigApplication implements CommandLineRunner {
@Autowired
private DataSource datasource;
@Override
public void run(String... args) throws Exception {
try(Connection conn = datasource.getConnection()) {
System.out.println(conn);
}
}
public static void main(String[] args) {
SpringApplication.run(DatasourceConfigApplication.class, args);
}
}
实现原理
Spring Boot使用如下方式整合HikariCP：入口是 org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration ，通过 org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration.Hikari 中的 @Bean 方式创建 com.zaxxer.hikari.HikariDataSource ：
/**
* Hikari DataSource configuration.
*/
@ConditionalOnClass(HikariDataSource.class)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource", matchIfMissing = true)
static class Hikari {
@Bean
@ConfigurationProperties(prefix = "spring.datasource.hikari")
public HikariDataSource dataSource(DataSourceProperties properties) {
HikariDataSource dataSource = createDataSource(properties,
HikariDataSource.class);
if (StringUtils.hasText(properties.getName())) {
dataSource.setPoolName(properties.getName());
}
return dataSource;
}
}
@ConfigurationProperties(prefix = "spring.datasource.hikari") 会自动把 spring.datasource.hikari.* 相关的连接池配置信息注入到创建的HikariDataSource实例中。
HikariCP的监控和遥测
因为在我们的微服务体系中使用的监控系统是Prometheus，这里以Prometheus为例。
注意spring boot 2.0对spring boot 1.x的metrics进行了重构，不再向后兼容，主要是在spring-boot-acutator中使用了micrometer，支持了更多的监控系统：Atlas、Datadog、Ganglia、Graphite、Influx、JMX、NewRelic、Prometheus、SignalFx、StatsD、Wavefront。Spring boot 2.0的metrics对比spring boot 1.x除了引入micrometer外，更大的体现是支持了tag，这也说明Prometheus、Influx等支持Tag的时序监控数据模型的监控系统已经成为主流。
在前面示例中的build.gradle中加入如下依赖：
implementation 'org.springframework.boot:spring-boot-starter-web' implementation 'org.springframework.boot:spring-boot-starter-actuator' implementation 'io.micrometer:micrometer-registry-prometheus'
配置文件applycation.yaml中加入对actuator的配置：
management: endpoints: web: exposure: include: "health,info,prometheus" server: port: 8079 servlet: context-path: /
注意这里引入了web和actuator依赖，通过配置 management.server.port 指定actuator的web端点为8089端口，通过 management.endpoints.include 对外开放 /actuator/prometheus ，在引入 io.micrometer:micrometer-registry-prometheus 依赖之后，端点 /actuator/prometheus 当即生效。
curl http://localhost:8079/actuator/prometheus | grep hikari
# TYPE hikaricp_connections_acquire_seconds summary
hikaricp_connections_acquire_seconds_count{pool="HikariPool-1",} 3.0
hikaricp_connections_acquire_seconds_sum{pool="HikariPool-1",} 0.001230082
# HELP hikaricp_connections_acquire_seconds_max Connection acquire time
# TYPE hikaricp_connections_acquire_seconds_max gauge
hikaricp_connections_acquire_seconds_max{pool="HikariPool-1",} 0.0
# HELP hikaricp_connections_min Min connections
# TYPE hikaricp_connections_min gauge
hikaricp_connections_min{pool="HikariPool-1",} 2.0
# TYPE hikaricp_connections_timeout_total counter
hikaricp_connections_timeout_total{pool="HikariPool-1",} 0.0
# HELP hikaricp_connections_pending Pending threads
# TYPE hikaricp_connections_pending gauge
hikaricp_connections_pending{pool="HikariPool-1",} 0.0
# HELP hikaricp_connections_usage_seconds Connection usage time
# TYPE hikaricp_connections_usage_seconds summary
hikaricp_connections_usage_seconds_count{pool="HikariPool-1",} 3.0
hikaricp_connections_usage_seconds_sum{pool="HikariPool-1",} 0.06
# HELP hikaricp_connections_usage_seconds_max Connection usage time
# TYPE hikaricp_connections_usage_seconds_max gauge
hikaricp_connections_usage_seconds_max{pool="HikariPool-1",} 0.0
# HELP hikaricp_connections_max Max connections
# TYPE hikaricp_connections_max gauge
hikaricp_connections_max{pool="HikariPool-1",} 10.0
# HELP hikaricp_connections Total connections
# TYPE hikaricp_connections gauge
hikaricp_connections{pool="HikariPool-1",} 2.0
# HELP hikaricp_connections_creation_seconds_max Connection creation time
# TYPE hikaricp_connections_creation_seconds_max gauge
hikaricp_connections_creation_seconds_max{pool="HikariPool-1",} 0.0
# HELP hikaricp_connections_creation_seconds Connection creation time
# TYPE hikaricp_connections_creation_seconds summary
hikaricp_connections_creation_seconds_count{pool="HikariPool-1",} 1.0
hikaricp_connections_creation_seconds_sum{pool="HikariPool-1",} 0.001
# HELP hikaricp_connections_idle Idle connections
# TYPE hikaricp_connections_idle gauge
hikaricp_connections_idle{pool="HikariPool-1",} 2.0
# HELP hikaricp_connections_active Active connections
# TYPE hikaricp_connections_active gauge
hikaricp_connections_active{pool="HikariPool-1",} 0.0
参考
• HikariCP
总结
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