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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3693) Deadlocks accessing DB metadata
Date Thu, 21 Aug 2008 11:50:46 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3693?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-3693:
--------------------------------------

    Attachment: nested_transaction_v2.diff

Here's a new version of the patch. Changes from the previous patch:

  1) only invalidate in a nested transaction for INTERNAL_RECOMPILE_REQUEST

  2) added regression test

Although (1) fixed most of the internal timeouts that were seen with the previous patch, I
still see one timeout in GrantRevokeDDLTest (no error, since the retry in the parent transaction
succeeds), so I don't think the patch should be committed yet. The timeout apparently happens
because GrantRevokeConstantAction invalidates statements with INTERNAL_RECOMPILE_REQUEST while
it's probably holding a lock in SYSSTATEMENTS.

The best way to fix this problem would be if we could make the logic to prevent waiting for
locks in SPSDescriptor.updateSYSSTATEMENTS() work for row locks. Currently, it only prevents
waiting for table locks. See also some discussion in DERBY-177.

> Deadlocks accessing DB metadata
> -------------------------------
>
>                 Key: DERBY-3693
>                 URL: https://issues.apache.org/jira/browse/DERBY-3693
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC
>    Affects Versions: 10.3.2.1, 10.3.3.0, 10.4.1.3
>         Environment: Linux amd64 or Windows 32bit
>            Reporter: Svata Dedic
>            Assignee: Knut Anders Hatlen
>         Attachments: d3693.java, deadlock.diff, derby.log, GetTables.java, nested_transaction.diff,
nested_transaction_v2.diff
>
>
> My code changes DB structure (create a column), then immediately after setting autocommit
back to true, the code rescans the DB metadata
> DatabaseMetaData.getColumns(catalog, schemaName, tableName, null);
> I am sometimes getting a deadlock with these operations:
> 2008-04-16 19:50:47.833 GMT Thread[Default RequestProcessor,1,system] (XID = 569844),
(SESSIONID = 2), (DATABASE = /..../a3/.config/localdb/db), (DRDAID = null), Cleanup action
starting 2008-04-16 19:50:47.833 GMT Thread[Default RequestProcessor,1,system] (XID = 569844),
(SESSIONID = 2),  (DATABASE = /..../IJCProjects/a3/.config/localdb/db), (DRDAID = null), Failed
Statement is: EXECUTE STATEMENT SYS."getColumns" ERROR 40XL2: A lock could not be obtained
within the time requested.
> The lockTable dump is:
> 2008-04-16 19:50:47.796 GMT
> XID       |TYPE         |MODE|LOCKCOUNT|LOCKNAME                                    
            |STATE|TABLETYPE /LOCKOBJ                   |INDEXNAME / CONTAINER_ID / MODE for
LATCH only)  |TABLENAME / CONGLOM_ID                |
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> *** The following row is the victim ***
> 569852    |ROW          |X   |0        |(44,7)                                      
         |WAIT |S                      |NULL |SYSSTATEMENTS                         | 
> *** The above row is the victim ***
> The stacktrace of the operation causing the deadlock is 
>         at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
>         at org.apache.derby.impl.services.locks.Timeout.createException(Unknown Source)
>         at org.apache.derby.impl.services.locks.Timeout.buildException(Unknown Source)
>         at org.apache.derby.impl.services.locks.ConcurrentLockSet.lockObject(Unknown
Source)
>         at org.apache.derby.impl.services.locks.AbstractPool.lockObject(Unknown Source)
>         at org.apache.derby.impl.services.locks.ConcurrentPool.lockObject(Unknown Source)
>         at org.apache.derby.impl.store.raw.xact.RowLocking3.lockRecordForWrite(Unknown
Source)
>         at org.apache.derby.impl.store.access.heap.HeapController.lockRow(Unknown Source)
>         at org.apache.derby.impl.store.access.heap.HeapController.lockRow(Unknown Source)
>         at org.apache.derby.impl.store.access.btree.index.B2IRowLocking3.lockRowOnPage(Unknown
Source)
>         at org.apache.derby.impl.store.access.btree.index.B2IRowLocking3._lockScanRow(Unknown
Source)
>         at org.apache.derby.impl.store.access.btree.index.B2IRowLockingRR.lockScanRow(Unknown
Source)
>         at org.apache.derby.impl.store.access.btree.BTreeForwardScan.fetchRows(Unknown
Source)
>         at org.apache.derby.impl.store.access.btree.BTreeScan.fetchNext(Unknown Source)

>         at org.apache.derby.impl.sql.catalog.TabInfoImpl.updateRow(Unknown Source) 
>         at org.apache.derby.impl.sql.catalog.TabInfoImpl.updateRow(Unknown Source)
>         at org.apache.derby.impl.sql.catalog.DataDictionaryImpl.updateSPS(Unknown Source
)
>         at org.apache.derby.iapi.sql.dictionary.SPSDescriptor.updateSYSSTATEMENTS(Unknown
Source)
>         at org.apache.derby.iapi.sql.dictionary.SPSDescriptor.getPreparedStatement(Unknown
Source)
>         at org.apache.derby.iapi.sql.dictionary.SPSDescriptor.getPreparedStatement(Unknown
Source)
>         at org.apache.derby.impl.sql.compile.ExecSPSNode.generate(Unknown Source)
>         at org.apache.derby.impl.sql.GenericStatement.prepMinion(Unknown Source)
>         at org.apache.derby.impl.sql.GenericStatement.prepare(Unknown Source)
>         at org.apache.derby.impl.sql.GenericPreparedStatement.rePrepare(Unknown Source)
>         at org.apache.derby.impl.sql.GenericPreparedStatement.execute(Unknown Source)
>         at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(Unknown Source)
>         at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Unknown
Source)
>         at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeQuery(Unknown Source)

>         at org.apache.derby.impl.jdbc.EmbedDatabaseMetaData.doGetCols(Unknown Source)
>         at org.apache.derby.impl.jdbc.EmbedDatabaseMetaData.getColumns(Unknown Source)
> I've seen the deadlock occur during several get-metadata operations (getImportedKeys,
...), each time waiting on the SYSSTATEMENTS apparently because of internally constructed
PreparedStatement. The lock eventually times out and the locked out operation completes without
error.
> When the deadlock occurs, the "real" SQL into systables is being compiled (I traced this
sql to be the value of "getColumns" key in org/apache/derby/impl/jdbc/metadata.properties
file):
> ---------%<-----------------------%<--------------
> Begin compiling prepared statement: SELECT CAST ('' AS VARCHAR(128)) AS PKTABLE_CAT,
S.SCHEMANAME AS PKTABLE_SCHEM, TABLENAME AS
> PKTABLE_NAME, COLS.COLUMNNAME AS PKCOLUMN_NAME, CAST ('' AS VARCHAR(128)) AS FKTABLE_CAT,
FKTABLE_SCHEM, FKTABLE_NAME, FKCOLUMN_NAME, CAST ...
> ---------%<-----------------------%<--------------

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