为什么 Hibernate 在一段时间后变慢？

Question

What could be a reason that hibernate slows down after while executing the same queries (read only)?

logs:

   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)
}

as you can see from the logs, the execution time increases tenfold

Answer 1

Hibernate c3p0 can be configured in order to increase efficiency. Connection pool is good for performance, as it prevents Java application create a connection each time when interact with database and minimizes the cost of opening and closing connections.

Try this link for configuring hibernate c3p0 in your application :

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