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https://issues.apache.org/jira/browse/DERBY-2861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12577233#action_12577233
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Kathey Marsden commented on DERBY-2861:
---------------------------------------
I can't seem to reproduce this on trunk or latest on 10.3. I get only lock
timeouts. e.g.
java.sql.SQLException: A lock could not be obtained within the time requested
at
org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(SQLExceptionFactory.java:45)
at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Util.java:201)
at
org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(TransactionResourceImpl.java:391)
at
org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(TransactionResourceImpl.java:346)
at
org.apache.derby.impl.jdbc.EmbedConnection.handleException(EmbedConnection.java:2082)
at
org.apache.derby.impl.jdbc.ConnectionChild.handleException(ConnectionChild.java:81)
at
org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(EmbedStatement.java:1325)
at
org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:625)
at
org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:555)
at
TestEmbeddedMultiThreading.executeStatement(TestEmbeddedMultiThreading.java:124)
at
TestEmbeddedMultiThreading.access$100(TestEmbeddedMultiThreading.java:25)
at
TestEmbeddedMultiThreading$ViewCreatorDropper.run(TestEmbeddedMultiThreading.java:189)
at java.lang.Thread.run(Thread.java:803)
Caused by: ERROR 40XL1: A lock could not be obtained within the time requested
at
org.apache.derby.iapi.error.StandardException.newException(StandardException.java:276)
at
org.apache.derby.impl.services.locks.ConcurrentLockSet.lockObject(ConcurrentLockSet.java:602)
at
org.apache.derby.impl.services.locks.AbstractPool.lockObject(AbstractPool.java:117)
at
org.apache.derby.impl.services.locks.ConcurrentPool.lockObject(ConcurrentPool.java:28)
at
org.apache.derby.impl.store.raw.xact.RowLocking2.lockRecordForRead(RowLocking2.java:165)
at
org.apache.derby.impl.store.access.btree.index.B2IRowLocking3._lockScan(B2IRowLocking3.java:127)
at
org.apache.derby.impl.store.access.btree.index.B2IRowLocking3.lockScan(B2IRowLocking3.java:739)
at
org.apache.derby.impl.store.access.btree.index.B2IRowLocking3._lockScanRow(B2IRowLocking3.java:662)
at
org.apache.derby.impl.store.access.btree.index.B2IRowLockingRR.lockScanRow(B2IRowLockingRR.java:112)
at
org.apache.derby.impl.store.access.btree.BTreeScan.positionAtStartForForwardScan(BTreeScan.java:436)
at
org.apache.derby.impl.store.access.btree.BTreeForwardScan.positionAtStartPosition(BTreeForwardScan.java:71)
at
org.apache.derby.impl.store.access.btree.BTreeForwardScan.fetchRows(BTreeForwardScan.java:123)
at
org.apache.derby.impl.store.access.btree.BTreeScan.next(BTreeScan.java:1756)
at
org.apache.derby.impl.sql.execute.IndexChanger.doDelete(IndexChanger.java:335)
at
org.apache.derby.impl.sql.execute.IndexChanger.delete(IndexChanger.java:544)
at
org.apache.derby.impl.sql.execute.IndexSetChanger.delete(IndexSetChanger.java:250)
at
org.apache.derby.impl.sql.execute.RowChangerImpl.deleteRow(RowChangerImpl.java:476)
at
org.apache.derby.impl.sql.catalog.TabInfoImpl.deleteRows(TabInfoImpl.java:750)
at
org.apache.derby.impl.sql.catalog.TabInfoImpl.deleteRow(TabInfoImpl.java:581)
at
org.apache.derby.impl.sql.catalog.DataDictionaryImpl.dropColumnDescriptorCore(DataDictionaryImpl.java:2950)
at
org.apache.derby.impl.sql.catalog.DataDictionaryImpl.dropAllColumnDescriptors(DataDictionaryImpl.java:2452)
at
org.apache.derby.iapi.sql.dictionary.ViewDescriptor.drop(ViewDescriptor.java:411)
at
org.apache.derby.impl.sql.execute.DropViewConstantAction.executeConstantAction(DropViewConstantAction.java:13
4)
at
org.apache.derby.impl.sql.execute.MiscResultSet.open(MiscResultSet.java:64)
at
org.apache.derby.impl.sql.GenericPreparedStatement.execute(GenericPreparedStatement.java:372)
at
org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(EmbedStatement.java:1235)
... 6 more
Are the lock timeouts expected? Can anyone still reproduce this?
> Thread safety issue in TableDescriptor
> --------------------------------------
>
> Key: DERBY-2861
> URL: https://issues.apache.org/jira/browse/DERBY-2861
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Environment: Tested on a dual-core 3GHz Pentium machine running
> Windows Vista Business, using JDK 1.4.2_13 and Derby trunk revision 548822.
> Reporter: Jeff Clary
> Attachments: TestEmbeddedMultiThreading.java
>
>
> A NullPointerException occurs in
> org.apache.derby.iapi.sql.dictionary.TableDescriptor.getObjectName when
> accessing the same object on many threads (each with its own connection).
> The attached test program starts N threads each creating and then dropping a
> separate view against the same source view, repeated M times. I can
> reproduce the problem with N=100 and M=100 on my machine, but not every run.
> An instance member named referencedColumnMap is checked for null at the top
> of the getObjectName method, but later when it is dereferenced it is null,
> because it was set to null by another thread. I am not sure what
> getObjectName is used for other than error reporting. I have considered a
> fix of just saving the non-null reference as a method variable, to avoid the
> later NullPointerException. But I don't know what unintended consequences
> this may have.
> When the test program does show the exception, the stack trace looks like
> this:
> java.lang.NullPointerException
> at
> org.apache.derby.iapi.sql.dictionary.TableDescriptor.getObjectName(TableDescriptor.java:758)
> at
> org.apache.derby.impl.sql.depend.BasicDependencyManager.getPersistentProviderInfos(BasicDependencyManager.java:677)
> at
> org.apache.derby.impl.sql.compile.CreateViewNode.bindViewDefinition(CreateViewNode.java:287)
> at
> org.apache.derby.impl.sql.compile.CreateViewNode.bind(CreateViewNode.java:183)
> at
> org.apache.derby.impl.sql.GenericStatement.prepMinion(GenericStatement.java:345)
> at
> org.apache.derby.impl.sql.GenericStatement.prepare(GenericStatement.java:119)
> at
> org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.prepareInternalStatement(GenericLanguageConnectionContext.java:745)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:568)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:517)
> at
> TestEmbeddedMultiThreading.executeStatement(TestEmbeddedMultiThreading.java:109)
> at
> TestEmbeddedMultiThreading.access$100(TestEmbeddedMultiThreading.java:10)
> at
> TestEmbeddedMultiThreading$ViewCreatorDropper.run(TestEmbeddedMultiThreading.java:173)
> at java.lang.Thread.run(Thread.java:534)
>
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