為什么 Hibernate 在一段時間后變慢？

Question

在執行相同的查詢（只讀）后，休眠速度變慢的原因可能是什么？

日志：

   368588 nanoseconds spent acquiring 1 JDBC connections;
   0 nanoseconds spent releasing 0 JDBC connections;
   158339 nanoseconds spent preparing 3 JDBC statements;
   33855736 nanoseconds spent executing 3 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);
   9437 nanoseconds spent executing 3 partial-flushes (flushing a total of 0 entities and 0 collections)
}
2020-03-24 09:02:54.488  INFO 12024 --- [io-8064-exec-10] i.StatisticalLoggingSessionEventListener : Session Metrics {
   44640 nanoseconds spent acquiring 1 JDBC connections;
   0 nanoseconds spent releasing 0 JDBC connections;
   134337 nanoseconds spent preparing 3 JDBC statements;
   33256438 nanoseconds spent executing 3 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);
   9156 nanoseconds spent executing 3 partial-flushes (flushing a total of 0 entities and 0 collections)
}
2020-03-24 09:02:56.143  INFO 12024 --- [nio-8064-exec-1] i.StatisticalLoggingSessionEventListener : Session Metrics {
   47060 nanoseconds spent acquiring 1 JDBC connections;
   0 nanoseconds spent releasing 0 JDBC connections;
   123461 nanoseconds spent preparing 3 JDBC statements;
   468759882 nanoseconds spent executing 3 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);
   9680 nanoseconds spent executing 3 partial-flushes (flushing a total of 0 entities and 0 collections)
}

從日志中可以看出，執行時間增加了十倍

Answer 1

可以配置 Hibernate c3p0 以提高效率。 連接池對性能有好處，因為它可以防止 Java 應用程序每次與數據庫交互時都創建連接，並最大限度地減少打開和關閉連接的成本。

嘗試使用此鏈接在您的應用程序中配置休眠 c3p0：

https://mkyong.com/hibernate/how-to-configure-the-c3p0-connection-pool-in-hibernate/