数据库连接池泄漏问题与解决办法

问题

启动后每运行一段时间，就会开始报错，且一直就是这个错误了：

java.sql.SQLTransientConnectionException: HikariPool-2 - Connection is not available, request timed out after 60000ms.
        at com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:689)
        at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:196)
        at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:161)
        at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:128)
        at com.huizhaofang.stats.service.processor.CompanyBasicsProcessor.getData(CompanyBasicsProcessor.java:36)
        at com.huizhaofang.stats.service.impl.CompanyBasicsServiceImpl.sendData(CompanyBasicsServiceImpl.java:33)
        at com.huizhaofang.stats.handler.qftstats.CompanyBasicsHandler.execute(CompanyBasicsHandler.java:25)
        at com.xxl.job.core.thread.JobThread$1.call(JobThread.java:134)
        at com.xxl.job.core.thread.JobThread$1.call(JobThread.java:131)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.lang.Thread.run(Thread.java:745)

看字面意思是超时，其实是连接池满了。通过在 config/logback.xml 调整 HikariPool 日志级别看看到：

    <Logger name="com.zaxxer.hikari" level="DEBUG">
        <appender-ref ref="STDOUT" />
    </Logger>

可观察到日志：

DEBUG com.zaxxer.hikari.pool.HikariPool:417 - HikariPool-1 - Pool stats (total=10, active=10, idle=0, waiting=0)

说明连接池由于泄漏导致耗尽了。

解决办法

务必在 finally 关闭 Connection

Connection conn = null;
try {
    conn = jdbcTemplate.getDataSource().getConnection();
    // 处理逻辑....
    return table;
} catch (IOException | SQLException e) {
    log.error("Exception:{}", e);
} finally {
    if (null != conn) {
        try {
            conn.close();
        } catch (SQLException e) {
        }
    }
}