db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5894) NPE in OnlineBackupTest1 while backing up in stubFileToRemoveAfterCheckPoint
Date Thu, 13 Dec 2012 09:49:23 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5894?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-5894:
--------------------------------------

    Attachment: d5894-1b-minimal-privileges.diff
                d5894-1a-minimal-change.diff

I'm attaching two alternative fixes for this issue.

d5894-1a-minimal-change.diff implements the minimal change to resolve the race condition.
It makes backupContainer() have its own privileged action, so that there's no state shared
with the other privileged operations, and hence no synchronization needed since there is no
race.

However, the current approach (not changed by the 1a patch) invokes the entire privBackupContainer()
method in a privileged block. It's a relatively big method, and only some portions actually
need to run with privileges.

The alternative patch d5894-1b-minimal-privileges.diff changes backupContainer() so that it
doesn't invoke all code in a privileged block. Instead, it uses helper methods with small
privileged blocks that do as little as possible apart from invoking the operations that need
privileges. In some cases existing helper methods could be used, but it also needed to add
some new ones (for copying a file, removing a file, and creating a RandomAccessFile).

Although the 1b patch adds more code than the 1a patch, I prefer the 1b patch, as it reduces
the risk of accidentally giving permissions to code that's not supposed to have them. Both
patches should solve the race condition, as they both ensure that backupContainer() does not
use any shared state without synchronization. (I haven't reproduced the NPE, though, so I
can't verify it.)

Regression tests ran cleanly with both of the patches.
                
> NPE in OnlineBackupTest1 while backing up in stubFileToRemoveAfterCheckPoint
> ----------------------------------------------------------------------------
>
>                 Key: DERBY-5894
>                 URL: https://issues.apache.org/jira/browse/DERBY-5894
>             Project: Derby
>          Issue Type: Bug
>          Components: Store
>            Reporter: Dag H. Wanvik
>            Assignee: Knut Anders Hatlen
>              Labels: derby_triage10_10
>         Attachments: d5894-1a-minimal-change.diff, d5894-1b-minimal-privileges.diff,
d5894.zip
>
>
> Saw this while running OnlineBackupTest1 trying to repro DERBY-973.
> ERROR 38000: The exception 'java.lang.NullPointerException' was thrown while evaluating
an expression.
>         at org.apache.derby.iapi.error.StandardException.newException(StandardException.java:288)
>         at org.apache.derby.iapi.error.StandardException.unexpectedUserException(StandardException.java:575)
>         at org.apache.derby.impl.services.reflect.ReflectMethod.invoke(ReflectMethod.java:63)
>         at org.apache.derby.impl.sql.execute.CallStatementResultSet.open(CallStatementResultSet.java:75)
>         at org.apache.derby.impl.sql.GenericPreparedStatement.executeStmt(GenericPreparedStatement.java:443)
>         at org.apache.derby.impl.sql.GenericPreparedStatement.execute(GenericPreparedStatement.java:324)
>         at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(EmbedStatement.java:1242)
>         at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(EmbedPreparedStatement.java:1715)
>         at org.apache.derby.impl.jdbc.EmbedCallableStatement.executeStatement(EmbedCallableStatement.java:118)
>         at org.apache.derby.impl.jdbc.EmbedPreparedStatement.execute(EmbedPreparedStatement.java:1370)
>         at org.apache.derbyTesting.functionTests.tests.store.OnlineBackup.performBackup(OnlineBackup.java:89)
>         at org.apache.derbyTesting.functionTests.tests.store.OnlineBackup.run(OnlineBackup.java:60)
>         at java.lang.Thread.run(Thread.java:637)
> Caused by: java.lang.NullPointerException
>         at java.util.Hashtable.put(Hashtable.java:401)
>         at org.apache.derby.impl.store.raw.data.BaseDataFileFactory.stubFileToRemoveAfterCheckPoint(BaseDataFileFactory.java:1613)
>         at org.apache.derby.impl.store.raw.data.RAFContainer.run(RAFContainer.java:1651)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at org.apache.derby.impl.store.raw.data.RAFContainer.backupContainer(RAFContainer.java:983)
>         at org.apache.derby.impl.store.raw.data.BaseContainerHandle.backupContainer(BaseContainerHandle.java:1031)
>         at org.apache.derby.impl.store.raw.data.BaseDataFileFactory.backupDataFiles(BaseDataFileFactory.java:2466)
>         at org.apache.derby.impl.store.raw.RawStore.backup(RawStore.java:978)
>         at org.apache.derby.impl.store.raw.RawStore.backup(RawStore.java:649)
>         at org.apache.derby.impl.store.access.RAMAccessManager.backup(RAMAccessManager.java:964)
>         at org.apache.derby.impl.db.BasicDatabase.backup(BasicDatabase.java:430)
>         at org.apache.derby.catalog.SystemProcedures.SYSCS_BACKUP_DATABASE(SystemProcedures.java:961)
>         at org.apache.derby.exe.acf33d40c7x0138x6d7cx6df3x0000720ad17b0.g0(Unknown Source)
>         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:592)
>         at org.apache.derby.impl.services.reflect.ReflectMethod.invoke(ReflectMethod.java:46)
>         ... 10 more

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message