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代码使用更多最大JDBC连接池的Hibernate（MySQL的）比预期
Session session = sessionFactorty.openSession();
session.beginTransaction();
session.save(userDetails);
session.save(userDetails1);
session.getTransaction().commit();
session.close();
Hibernate配置
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
对于这种配置，我得到错误：内部连接池已达到其最大尺寸
INFO: HHH000476: Executing import script 'org.hiber[email protected]2b4c1d96'Exception in thread "main" org.hibernate.HibernateException: The internal connection pool has reached its maximum size and no connection is currently available!
at org.hibernate.engine.jdbc.connections.internal.PooledConnections.poll(PooledConnections.java:82)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.getConnection(DriverManagerConnectionProviderImpl.java:186)
at org.hibernate.internal.NonContextualJdbcConnectionAccess.obtainConnection(NonContextualJdbcConnectionAccess.java:35)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcIsolationDelegate.delegateWork(JdbcIsolationDelegate.java:48)
at org.hibernate.id.enhanced.TableStructure$1.getNextValue(TableStructure.java:125)
at org.hibernate.id.enhanced.NoopOptimizer.generate(NoopOptimizer.java:40)
at org.hibernate.id.enhanced.SequenceStyleGenerator.generate(SequenceStyleGenerator.java:432)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:105)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:682)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:674)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:669)
将connection.pool_size增加到2解决了问题。我期望它只使用一个连接。
问题：是一种预期的行为？为什么它发生？
嗯，我会说这是**预计不会建立一个连接池只有一个连接**。无论如何，[似乎]（https://github.com/hibernate/hibernate-orm/blob/master/hibernate-core/src/main/java/org/hibernate/engine/jdbc/connections/internal/PooledConnections.java# L73）没有可用的连接，并且在引发此异常时不可能* addConnection *。您可能需要检查* size（）*以查看是否有可用连接... –