Java程序数据库连接满问题的排查指南

// 获取HikariCP连接池状态
HikariPoolMXBean pool = dataSource.getHikariPoolMXBean();
System.out.printf("连接池状态: 活跃=%d, 空闲=%d, 等待=%d, 总=%d%n",
    pool.getActiveConnections(),
    pool.getIdleConnections(),
    pool.getThreadsAwaitingConnection(),
    pool.getTotalConnections());

-- MySQL
SHOW STATUS LIKE 'Threads_connected';
SHOW PROCESSLIST;

-- PostgreSQL
SELECT count(*) FROM pg_stat_activity;
SELECT * FROM pg_stat_activity WHERE state = 'active';

-- Oracle
SELECT count(*) FROM v$session;
SELECT sid, serial#, username, status FROM v$session WHERE type = 'USER';

// HikariCP泄漏检测配置(单位毫秒)
spring.datasource.hikari.leak-detection-threshold=60000

// Druid泄漏检测
spring.datasource.druid.remove-abandoned=true
spring.datasource.druid.remove-abandoned-timeout=60

// 反例1：未关闭ResultSet/Statement
Connection conn = dataSource.getConnection();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM table");
// 忘记调用rs.close(), stmt.close(), conn.close()

// 反例2：try-with-resources使用不当
try (Connection conn = dataSource.getConnection()) {
    Statement stmt = conn.createStatement(); // 未包含在try中
    // ...
} // stmt不会被自动关闭

-- MySQL长事务查询
SELECT trx_id, trx_started, TIMEDIFF(NOW(), trx_started) duration, 
       trx_query, trx_state 
FROM information_schema.INNODB_TRX 
ORDER BY trx_started ASC;

// 标准写法
try (Connection conn = dataSource.getConnection();
     Statement stmt = conn.createStatement();
     ResultSet rs = stmt.executeQuery(sql)) {
    // 处理结果集
} // 自动关闭所有资源

// Spring事务正确用法
@Transactional
public void serviceMethod() {
    // 只包含数据库操作
    repository.update(data);
    // 不包含: 文件IO、网络请求、长时间计算
}

# 推荐HikariCP配置
spring:
  datasource:
    hikari:
      maximum-pool-size: 20      # 根据DB负载能力调整
      minimum-idle: 5            # 可减少初始连接数
      connection-timeout: 30000  # 30秒获取连接超时
      max-lifetime: 1800000      # 30分钟连接最大存活
      idle-timeout: 600000       # 10分钟空闲超时
      leak-detection-threshold: 60000 # 60秒泄漏检测

-- 终止问题连接(MySQL示例)
KILL <process_id>;

-- 批量终止空闲连接
SELECT concat('KILL ', id, ';') 
FROM information_schema.processlist 
WHERE Command = 'Sleep' AND Time > 300;

<!-- SpotBugs插件检测资源泄漏 -->
<plugin>
    <groupId>com.github.spotbugs</groupId>
    <artifactId>spotbugs-maven-plugin</artifactId>
    <version>4.7.3</version>
</plugin>

// 使用JMeter模拟并发场景
@Test
public void testConnectionPoolUnderLoad() {
    // 模拟100并发持续请求
    StressTestUtils.concurrentTest(100, () -> {
        service.processRequest(testData);
    });
}

# 监控方法调用
watch com.example.service.*Service * '{params, returnObj, throwExp}' -n 5 -x 3

# 追踪连接获取
trace javax.sql.DataSource getConnection

# 生成线程dump
jstack <pid> > thread_dump.log

# 分析持有连接的线程
grep -A 30 "java.sql.Connection" thread_dump.log