Hibernate统计日志记录

Question

我在解释Hibernate会话日志时有点卡住了。我的主要问题是许多查询有点慢 - 基于我实现的一些 TimeWatch 日志记录。为了进一步跟踪问题，我启用了Hibernate会话日志记录，目的是查看执行查询或获取连接的时间是否浪费（我猜这意味着配置错误）。

关于用例——Oracle DB、Spring、Hibernate。在“繁忙时间”，最多有15个线程对数据库执行查询。我想没什么特别的。

现在我看到hibernate会话日志如下。

2017-03-30 13:35:13.834+0200 [process-documents-task-6] I [/] o.h.e.i.StatisticalLoggingSessionEventListener - Session Metrics {
    636713687 nanoseconds spent acquiring 1 JDBC connections;
    57993 nanoseconds spent releasing 1 JDBC connections;
    636859879 nanoseconds spent preparing 1 JDBC statements;
    2231526 nanoseconds spent executing 1 JDBC statements;
    0 nanoseconds spent executing 0 JDBC batches;
    0 nanoseconds spent performing 0 L2C puts;
    0 nanoseconds spent performing 0 L2C hits;
    0 nanoseconds spent performing 0 L2C misses;
    0 nanoseconds spent executing 0 flushes (flushing a total of 0 entities and 0 collections);
    9261 nanoseconds spent executing 1 partial-flushes (flushing a total of 0 entities and 0 collections)

或

2017-03-30 13:35:16.073+0200 [process-documents-task-8] I [/] o.h.e.i.StatisticalLoggingSessionEventListener - Session Metrics {
    2893793341 nanoseconds spent acquiring 1 JDBC connections;
    22196 nanoseconds spent releasing 1 JDBC connections;
    2893869403 nanoseconds spent preparing 1 JDBC statements;
    1509926 nanoseconds spent executing 1 JDBC statements;
    0 nanoseconds spent executing 0 JDBC batches;
    0 nanoseconds spent performing 0 L2C puts;
    0 nanoseconds spent performing 0 L2C hits;
    0 nanoseconds spent performing 0 L2C misses;
    0 nanoseconds spent executing 0 flushes (flushing a total of 0 entities and 0 collections);
    4056 nanoseconds spent executing 1 partial-flushes (flushing a total of 0 entities and 0 collections)

但是这到底是什么意思呢？

我现在的解读

• 执行查询的 1509926 纳秒（1.5 毫秒）：似乎没问题
• 获取连接的2893793341纳秒（2.8 秒）：不行:(
• 准备语句的2893869403纳秒（2.8 秒）：不行:(

准备语句是什么意思？从我从javadoc中读到的内容来看，它可能意味着查询被发送到数据库进行优化。但是为什么总是在获取连接需求的时候呢？

关于如何进一步追踪问题，根本原因的任何建议？

或者关于问题可能是什么的任何提示？

谢谢你的帮助！

最诚挚的问候，斯特凡

Answer 1

默认的HiberNate统计信息不是很丰富。我们计划在HiberNate的未来版本中增强这方面。

但是，您可以提供自己的统计实现，该实现构建在Dropw的指标之上。

简而言之，假设你有一个扩展org.hibernate.stat.internal.ConcurrentStatisticsImpl的TransactionStatistics类：

public class TransactionStatistics extends ConcurrentStatisticsImpl {

    private static final ThreadLocal<AtomicLong> startNanos = new ThreadLocal<AtomicLong>() {
        @Override protected AtomicLong initialValue() {
            return new AtomicLong();
        }
    };

    private static final ThreadLocal<AtomicLong> connectionCounter = new ThreadLocal<AtomicLong>() {
        @Override protected AtomicLong initialValue() {
            return new AtomicLong();
        }
    };

    private StatisticsReport report = new StatisticsReport();

    @Override public void connect() {
        connectionCounter.get().incrementAndGet();
        startNanos.get().compareAndSet(0, System.nanoTime());
        super.connect();
    }

    @Override public void endTransaction(boolean success) {
        try {
            report.transactionTime(System.nanoTime() - startNanos.get().get());
            report.connectionsCount(connectionCounter.get().get());
            report.generate();
        } finally {
            startNanos.remove();
            connectionCounter.remove();
        }
        super.endTransaction(success);
    }
}

您需要创建一个< code>StatisticsFactory实现:

public class TransactionStatisticsFactory implements StatisticsFactory {

    @Override
    public StatisticsImplementor buildStatistics(SessionFactoryImplementor sessionFactory) {
        return new TransactionStatistics();
    }
}

并像这样配置它：

<property 
    name="hibernate.stats.factory", 
    value="com.vladmihalcea.book.hpjp.hibernate.statistics.TransactionStatisticsFactory"
/> 

等等！

现在，您可以监控统计数据并将其导出为 Dropwizard Metrics 支持的任何格式。而且，Dropwizard 指标使用各种水库，因此您可以为您的用例选择最佳水库。

要查看Dropwizard Metrics的真正功能，请查看FlexyPool。