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https://issues.apache.org/jira/browse/DERBY-4193?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Knut Anders Hatlen updated DERBY-4193:
--------------------------------------
Attachment: d4193-1b.diff
An alternative to using lockNonScan* methods for the problematic cases is to
add a flag to lockScanRow() to state whether or not the position should be
saved if the latch is released. See the attached patch.
I'll try to write some test cases that trigger the assert from the other
methods mentioned above.
> ASSERT FAILED Scan position already saved with multi-threaded
> insert/update/delete
> -----------------------------------------------------------------------------------
>
> Key: DERBY-4193
> URL: https://issues.apache.org/jira/browse/DERBY-4193
> Project: Derby
> Issue Type: Bug
> Components: Store
> Affects Versions: 10.5.1.1, 10.6.0.0
> Environment: Windows XP, IBM 1.6 SR6, Sun 1.6.0_01-b06
> Reporter: Kathey Marsden
> Assignee: Knut Anders Hatlen
> Attachments: btreemaxscancomments.diff, d4193-1a.diff, d4193-1b.diff,
> ScanPosSaved.java, ScanPosSaved.java
>
>
> The attached program ScanPosSaved.java produces the error below, fairly
> quickly.
> The program has three threads, one doing inserts into a table with an
> identity column, one updating the row with the maximum id, one deleting the
> row with the maximum id.
> To reproduce, run >java ScanPosSaved and <ctrl> <c> out of the program after
> you get the error.
> I saw this 10.5 and trunk sane builds but did not see it on 10.4. With the
> insane build of 10.5.1.1 (RC2) I did not see any symptoms right away, so
> don't know how serious an issue this is for insane builds.
> org.apache.derby.shared.common.sanity.AssertFailure: ASSERT FAILED Scan
> position already saved
> at
> org.apache.derby.shared.common.sanity.SanityManager.ASSERT(SanityManager.java:120)
> at
> org.apache.derby.impl.store.access.btree.BTreeScan.savePositionAndReleasePage(BTreeScan.java:2148)
> at
> org.apache.derby.impl.store.access.btree.BTreeScan.savePositionAndReleasePage(BTreeScan.java:2212)
> at
> org.apache.derby.impl.store.access.btree.BTreeRowPosition.saveMeAndReleasePage(BTreeRowPosition.java:128)
> at
> org.apache.derby.impl.store.access.btree.index.B2IRowLocking3.lockRowOnPage(B2IRowLocking3.java:295)
> at
> org.apache.derby.impl.store.access.btree.index.B2IRowLocking3._lockScanRow(B2IRowLocking3.java:599)
> at
> org.apache.derby.impl.store.access.btree.index.B2IRowLockingRR.lockScanRow(B2IRowLockingRR.java:105)
> at
> org.apache.derby.impl.store.access.btree.BTreeMaxScan.positionAtStartPosition(BTreeMaxScan.java:347)
> at
> org.apache.derby.impl.store.access.btree.BTreeMaxScan.fetchMax(BTreeMaxScan.java:434)
> at
> org.apache.derby.impl.store.access.btree.index.B2I.fetchMaxOnBTree(B2I.java:739)
> at
> org.apache.derby.impl.store.access.RAMTransaction.fetchMaxOnBtree(RAMTransaction.java:1078)
> at
> org.apache.derby.impl.sql.execute.LastIndexKeyResultSet.openCore(LastIndexKeyResultSet.java:189)
> at
> org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(ProjectRestrictResultSet.java:168)
> at
> org.apache.derby.impl.sql.execute.ScalarAggregateResultSet.openCore(ScalarAggregateResultSet.java:133)
> at
> org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(ProjectRestrictResultSet.java:168)
> at
> org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl.open(BasicNoPutResultSetImpl.java:245)
> at
> org.apache.derby.impl.sql.GenericPreparedStatement.executeStmt(GenericPreparedStatement.java:416)
> at
> org.apache.derby.impl.sql.GenericPreparedStatement.execute(GenericPreparedStatement.java:297)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(EmbedStatement.java:1235)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:625)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.executeQuery(EmbedStatement.java:152)
> at ScanPosSaved.updateOperation(ScanPosSaved.java:62)
> at ScanPosSaved$3.run(ScanPosSaved.java:17)
> I discovered this when trying to get a smaller repro for DERBY-4181, but I
> think it is a different issue, because it reproduces on multiple jvms and
> does not reproduce on 10.4. The assertion was added with DERBY-2991. Knut
> could you perhaps assess how serious this is?
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