监控空闲连接数 ，活动连接，总连接数，等待连接的线程数是非常短暂的。由于每个统计数据都是时间敏感的，并且是独立收集的，所以在短时间内可能无法“累计”。不要基于这些值进行任何编程决策，它们仅用于监视。‍

@Slf4j
public class DataSourceMonitor {
   private HikariPoolMXBean proxy;


   private boolean hasStarted;


   @Resource
   private HikariDataSource hikariDataSource;


   @Scheduled(cron = "0/1 * * * * *")
  public void monitor() {
      try {
            if (null == proxy) {
                 MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer();
                 ObjectName poolName = new ObjectName("com.zaxxer.hikari:type=Pool (" + hikariDataSource.getPoolName() + ")");
                 proxy = JMX.newMXBeanProxy(mBeanServer, poolName, HikariPoolMXBean.class);
           } else {
                 log.info("{}, {}, {}, {}", proxy.getTotalConnections(), proxy.getActiveConnections(), proxy.getIdleConnections(), proxy.getThreadsAwaitingConnection());
           }
       } catch (Throwable cause) {
           log.error("fail》》", cause);
       }
   }
}

配置 

spring.datasource.hikari.register-mbeans=true

必须得至少获取一个连接, 不然会一直报错

java.lang.reflect.UndeclaredThrowableException: null
at com.sun.proxy.$Proxy174.getTotalConnections(Unknown Source) ~[?:?]
at com.bestpay.redbag.web.controller.MrathenaController.datasource(MrathenaController.java:38) ~[classes/:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_202]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_202]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_202]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_202]
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_202]

可配调整如下配置来测试效果

spring.datasource.hikari.maximum-pool-size=50
spring.datasource.hikari.minimum-idle=50
spring.datasource.hikari.connection-timeout=250

监控 Hikari 连接数的最好实现方式是，参考 源码logPoolState

/**
 * @see HikariPool#logPoolState(java.lang.String...)
 */
public static String poolState(HikariDataSource dataSource, boolean ifLog, String... prefix) {
      String poolName = dataSource.getPoolName();
      HikariPoolMXBean mx = dataSource.getHikariPoolMXBean();
      String format = String.format("%s - %sstats (total=%d, active=%d, idle=%d, waiting=%d)",
            poolName, (prefix.length > 0 ? prefix[0] : ""),
      mx.getTotalConnections(), mx.getActiveConnections(), mx.getIdleConnections(), mx.getThreadsAwaitingConnection());
      return format;
}

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