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我们有一大组测试运行在内存数据库中。每个测试都会创建其模式。单元测试在内存中H2 db非常慢
到目前为止，我们对HSQL DB运行这些测试，但由于H2应该更快，我们尝试切换到H2。
查看执行时间H2实际上明显更快（10-50％）。但是当进行大量测试时，H2似乎需要休息一下，导致整体性能比HSQLDB（800-900％）差得多。
任何想法如何保持整个测试套件单一测试的良好性能？
这些都是我们试图为H2的网址：
jdbc:h2:mem:testdb
jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1
jdbc:h2:mem:testdb;MVCC=true
jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;MODE=Oracle;MVCC=true
这就是我们与HSQL DB使用：
jdbc:hsqldb:mem:testdb
编辑：
我试着写一个reprodocable测试用例，但这并不容易，因为当我们只使用简单的jdbc时，我们似乎没有问题。大约500次测试都使用休眠后，测试变得缓慢。
我注意到VisualVM唯一的事情就是CPU的使用率下降到接近于零，同时测试开始时速度很慢。
编辑2：
JStack输出：
2011-11-21 08:42:34
Full thread dump Java HotSpot(TM) Client VM (16.3-b01 mixed mode):
"ReaderThread" prio=6 tid=0x18e47400 nid=0x318 runnable [0x190ef000]
java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:129)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:264)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:306)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158)
- locked <0x099d61c0> (a java.io.InputStreamReader)
at java.io.InputStreamReader.read(InputStreamReader.java:167)
at java.io.BufferedReader.fill(BufferedReader.java:136)
at java.io.BufferedReader.readLine(BufferedReader.java:299)
- locked <0x099d61c0> (a java.io.InputStreamReader)
at java.io.BufferedReader.readLine(BufferedReader.java:362)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner$ReaderThread.run(RemoteTestRunner.java:140)
Locked ownable synchronizers:
- None
"Low Memory Detector" daemon prio=6 tid=0x0244c400 nid=0x908 runnable [0x00000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"CompilerThread0" daemon prio=10 tid=0x02447800 nid=0x10fc waiting on condition [0x00000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"Attach Listener" daemon prio=10 tid=0x02446400 nid=0x930 waiting on condition [0x00000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"Signal Dispatcher" daemon prio=10 tid=0x02443400 nid=0xf08 runnable [0x00000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"Finalizer" daemon prio=8 tid=0x02412400 nid=0x13cc in Object.wait() [0x186bf000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x099d6410> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:118)
- locked <0x099d6410> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:134)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)
Locked ownable synchronizers:
- None
"Reference Handler" daemon prio=10 tid=0x0240d800 nid=0xbe4 in Object.wait() [0x1862f000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x099d6498> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:485)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)
- locked <0x099d6498> (a java.lang.ref.Reference$Lock)
Locked ownable synchronizers:
- None
"main" prio=6 tid=0x0011e000 nid=0x1028 in Object.wait() [0x003ce000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x09efc2a0> (a org.h2.engine.Database)
at org.h2.table.RegularTable.doLock(RegularTable.java:520)
at org.h2.table.RegularTable.lock(RegularTable.java:434)
- locked <0x09efc2a0> (a org.h2.engine.Database)
at org.h2.command.ddl.AlterTableAddConstraint.tryUpdate(AlterTableAddConstraint.java:93)
at org.h2.command.ddl.AlterTableAddConstraint.update(AlterTableAddConstraint.java:68)
at org.h2.command.CommandContainer.update(CommandContainer.java:73)
at org.h2.command.Command.executeUpdate(Command.java:219)
- locked <0x09efc2a0> (a org.h2.engine.Database)
at org.h2.jdbc.JdbcStatement.executeUpdateInternal(JdbcStatement.java:125)
- locked <0x0b69dd50> (a org.h2.engine.Session)
at org.h2.jdbc.JdbcStatement.executeUpdate(JdbcStatement.java:110)
at org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:421)
at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:379)
at org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:273)
at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:219)
at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:372)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1845)
at de.xyz.dps.server.core.database.HibernateUtil.createSessionFactory(HibernateUtil.java:55)
at de.xyz.dps.server.core.database.HibernateUtil.getSessionFactory(HibernateUtil.java:40)
at de.xyz.dps.server.core.database.TransactionContext.getContext(TransactionContext.java:52)
at de.xyz.dps.server.core.serviceimpl.AbstractDatabaseService.getSession(AbstractDatabaseService.java:53)
at de.xyz.dps.server.core.serviceimpl.AbstractDatabaseService.save(AbstractDatabaseService.java:36)
at de.xyz.dps.server.core.serviceimpl.AbstractDatabaseService.save(AbstractDatabaseService.java:31)
at de.xyz.dps.server.authentication.serviceimpl.DatabaseUserServiceTest.prepareAndSaveATechnicalSectionTO(DatabaseUserServiceTest.java:328)
at de.xyz.dps.server.authentication.serviceimpl.DatabaseUserServiceTest.setup(DatabaseUserServiceTest.java:87)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)
at de.xyz.dps.server.core.database.SessionFactoryRule$1.evaluate(SessionFactoryRule.java:90)
at de.xyz.dps.common.util.ThreadRegistryRule$1.evaluate(ThreadRegistryRule.java:34)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Locked ownable synchronizers:
- None
"VM Thread" prio=10 tid=0x0240a400 nid=0x102c runnable
"VM Periodic Task Thread" prio=10 tid=0x0245e400 nid=0xdf4 waiting on condition
JNI global references: 967
似乎创建模式时的测试正在等待某些DB锁。
编辑3：
这似乎是与多个连接的问题。当我用jdbc：h2：mem：（未命名的私有;一个连接）替换jdbc：h2：mem：test（一个进程中的多个连接）时，一切正常（但比hsql db慢10％）。
编辑4：
好吧，我跑对文件分贝测试，并能找到这样的跟踪文件。这里的问题是一样的。 trace file
我不知道可能是什么原因。你能发布一个可重复的测试用例吗？如果没有，你可以运行一个分析工具来找出问题出在哪里？ –
我已经做了一些与VisualVM分析，更新问题。 – snieke
使用内存数据库时，CPU使用率低*非常奇怪...你可以得到一些完整的线程转储（'jstack -l'），如果是这种情况并发布它们？ –