Vova Vysotskyi created ZOOKEEPER-3803:
-----------------------------------------
Summary: FileTxnSnapLog.fastForwardFromEdits() throws NPE if
TestingServer is started from another thread
Key: ZOOKEEPER-3803
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3803
Project: ZooKeeper
Issue Type: Bug
Affects Versions: 3.4.13
Reporter: Vova Vysotskyi
For the case when {{TestingServer.start()}} and {{TestingServer.close()}}
methods are running in different threads (but {{TestingServer.close()}} is
executed after {{TestingServer.start()}} is complited),
{{FileTxnSnapLog.fastForwardFromEdits()}} throws NPE, since
{{FileTxnSnapLog.close()}} was already called in
{{TestingZooKeeperMain.internalRunFromConfig()}} method.
Such a case may be observed in unit tests when start and close methods are
called in methods annotated with {{@Before}} and {{@After}} annotations.
Here is a simple test which helps to reproduce this issue:
{code:java}
@Test
public void testNPE() throws Exception {
for (int i = 0; i < 100; i++) {
TestingServer testingServer = new TestingServer();
Thread thread = new Thread(() -> {
try {
testingServer.start();
} catch (Exception e) {
throw new RuntimeException(e);
}
});
thread.start();
thread.join();
testingServer.close();
}
}
{code}
The stack trace is the following:
{noformat}
java.lang.NullPointerException
at
org.apache.zookeeper.server.persistence.FileTxnSnapLog.fastForwardFromEdits(FileTxnSnapLog.java:269)
at
org.apache.zookeeper.server.ZKDatabase.fastForwardDataBase(ZKDatabase.java:251)
at
org.apache.zookeeper.server.ZooKeeperServer.shutdown(ZooKeeperServer.java:583)
at
org.apache.zookeeper.server.ZooKeeperServer.shutdown(ZooKeeperServer.java:546)
at
org.apache.zookeeper.server.NIOServerCnxnFactory.shutdown(NIOServerCnxnFactory.java:929)
at
org.apache.curator.test.TestingZooKeeperMain.close(TestingZooKeeperMain.java:178)
at
org.apache.curator.test.TestingZooKeeperServer.stop(TestingZooKeeperServer.java:118)
at
org.apache.curator.test.TestingZooKeeperServer.close(TestingZooKeeperServer.java:130)
at org.apache.curator.test.TestingServer.close(TestingServer.java:178)
at
org.apache.drill.exec.coord.zk.TestZookeeperClient.testNPE(TestZookeeperClient.java:109)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at
org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at
org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at
org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at
mockit.integration.junit4.JUnit4TestRunnerDecorator.executeTestMethod(JUnit4TestRunnerDecorator.java:157)
at
mockit.integration.junit4.JUnit4TestRunnerDecorator.invokeExplosively(JUnit4TestRunnerDecorator.java:71)
at
mockit.integration.junit4.FakeFrameworkMethod.invokeExplosively(FakeFrameworkMethod.java:29)
at
org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java)
at
org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at
org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at
org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at
org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at
org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at
com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at
com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at
com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
{noformat}
Looks like this NPE is a regression after ZOOKEEPER-2845, where instead of
using a local variable of {{txnLog}} was used class field.
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