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https://issues.apache.org/jira/browse/HIVE-11935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15064653#comment-15064653
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Daniel Dai commented on HIVE-11935:
-----------------------------------
Yes, this is about thread synchronization. The test we saw is a concurrency
test. The only reason HS2 throw the exception is isCompatibleWith and close are
called by different threads and mixed temporally. The patch take Sergey's route
which make a local copy of currentMetaVars. There is slight chance that close
get called between check and make local copy, but chance is much smaller since
we are safe in the while loop.
> Access HiveMetaStoreClient.currentMetaVars should be synchronized
> -----------------------------------------------------------------
>
> Key: HIVE-11935
> URL: https://issues.apache.org/jira/browse/HIVE-11935
> Project: Hive
> Issue Type: Bug
> Components: Metastore
> Affects Versions: 1.2.1
> Reporter: Daniel Dai
> Assignee: Daniel Dai
> Attachments: HIVE-11935.1.patch, HIVE-11935.2.patch
>
>
> We saw intermittent failure of the following stack:
> {code}
> java.lang.NullPointerException
> at
> org.apache.hadoop.hive.metastore.HiveMetaStoreClient.isCompatibleWith(HiveMetaStoreClient.java:287)
> at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:497)
> at
> org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.invoke(RetryingMetaStoreClient.java:156)
> at com.sun.proxy.$Proxy9.isCompatibleWith(Unknown Source)
> at org.apache.hadoop.hive.ql.metadata.Hive.get(Hive.java:206)
> at
> org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.createHiveDB(BaseSemanticAnalyzer.java:205)
> at
> org.apache.hadoop.hive.ql.parse.DDLSemanticAnalyzer.<init>(DDLSemanticAnalyzer.java:223)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzerFactory.get(SemanticAnalyzerFactory.java:259)
> at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:409)
> at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:308)
> at org.apache.hadoop.hive.ql.Driver.compileInternal(Driver.java:1122)
> at
> org.apache.hadoop.hive.ql.Driver.compileAndRespond(Driver.java:1116)
> at
> org.apache.hive.service.cli.operation.SQLOperation.prepare(SQLOperation.java:110)
> at
> org.apache.hive.service.cli.operation.SQLOperation.runInternal(SQLOperation.java:181)
> at
> org.apache.hive.service.cli.operation.Operation.run(Operation.java:257)
> at
> org.apache.hive.service.cli.session.HiveSessionImpl.executeStatementInternal(HiveSessionImpl.java:388)
> at
> org.apache.hive.service.cli.session.HiveSessionImpl.executeStatementAsync(HiveSessionImpl.java:375)
> at sun.reflect.GeneratedMethodAccessor21.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:497)
> at
> org.apache.hive.service.cli.session.HiveSessionProxy.invoke(HiveSessionProxy.java:78)
> at
> org.apache.hive.service.cli.session.HiveSessionProxy.access$000(HiveSessionProxy.java:36)
> at
> org.apache.hive.service.cli.session.HiveSessionProxy$1.run(HiveSessionProxy.java:63)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:422)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
> at
> org.apache.hive.service.cli.session.HiveSessionProxy.invoke(HiveSessionProxy.java:59)
> at com.sun.proxy.$Proxy20.executeStatementAsync(Unknown Source)
> at
> org.apache.hive.service.cli.CLIService.executeStatementAsync(CLIService.java:274)
> at
> org.apache.hive.service.cli.thrift.ThriftCLIService.ExecuteStatement(ThriftCLIService.java:486)
> at
> org.apache.hive.service.cli.thrift.TCLIService$Processor$ExecuteStatement.getResult(TCLIService.java:1313)
> at
> org.apache.hive.service.cli.thrift.TCLIService$Processor$ExecuteStatement.getResult(TCLIService.java:1298)
> at org.apache.thrift.ProcessFunction.process(ProcessFunction.java:39)
> at
> org.apache.hive.service.cli.thrift.TCLIService$Processor$ExecuteStatement.getResult(TCLIService.java:1298)
> at org.apache.thrift.ProcessFunction.process(ProcessFunction.java:39)
> at org.apache.thrift.TBaseProcessor.process(TBaseProcessor.java:39)
> at org.apache.thrift.server.TServlet.doPost(TServlet.java:83)
> at
> org.apache.hive.service.cli.thrift.ThriftHttpServlet.doPost(ThriftHttpServlet.java:171)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
> at
> org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:565)
> at
> org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:479)
> at
> org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:225)
> at
> org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1031)
> at
> org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:406)
> at
> org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:186)
> at
> org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:965)
> at
> org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117)
> at
> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:111)
> at org.eclipse.jetty.server.Server.handle(Server.java:349)
> at
> org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:449)
> at
> org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:925)
> at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:857)
> at
> org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
> at
> org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:76)
> at
> org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:609)
> at
> org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:45)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {code}
> HiveMetaStoreClient.isCompatibleWith does a null check of currentMetaVars in
> the beginning, but it is possible HiveMetaStoreClient.close is invoked before
> it gets used, thus we will see the above stack. Access of currentMetaVars
> should be synchronized.
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