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: 10.4.1.3, 10.3.3.0, 10.3.2.1
Environment: Linux amd64 or Windows 32bit
Reporter: Svata Dedic
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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