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Knut Anders Hatlen commented on DERBY-3362:
-------------------------------------------
The method BTreePostCommit.purgeRowLevelCommittedDeletes() was added
in 10.3.2.1 (DERBY-3216), which explains why this is not seen on
10.3.1.4.
In that issue, I posted the following question after reviewing the
code (no answer from the submitter, though):
In the same method, I see this piece of code:
+ if ((controlRow = ControlRow.get(open_btree, page_number)) == null)
+ return;
As far as I can see, it is impossible that ControlRow.get() returns
null, so by returning successfully when controlRow is null, we might
be hiding future bugs. Wouldn't it be better to skip the null
checking and just let the method fail with an NPE when controlRow is
dereferenced?
Looking at it again, I'm wondering if the check is actually there to
ensure that purgeRowLevelCommittedDeletes() is a no-op if the page
doesn't exist. However, it is wrong since ControlRow.get() will fail
instead of returning null if the page cannot be found.
Would it work if we changed the above mentioned code like this?
Page p = open_btree.container.getPage(page_number);
if (p == null) {
// page doesn't exist, no rows to reclaim
return;
}
controlRow = ControlRow.getControlRowForPage();
In that case, the null check would make sense, and I think the NPE
would go away.
ControlRow NPE
--------------
Key: DERBY-3362
URL: https://issues.apache.org/jira/browse/DERBY-3362
Project: Derby
Issue Type: Bug
Affects Versions: 10.3.2.1
Reporter: James Alan Shepherd
Attachments: derbylog.zip
I have a NPE in Derby 10.3.2.1 (10.3.1.4 does not show this behaviour) that is
probably the same one discussed in DERBY-3216
FATAL 38406 [Main] (Start.java:153) - Start FAILED
org.springframework.transaction.TransactionSystemException: Could not commit
JDBC transaction; nested exception is java.sql.SQLException: Java exception: ':
java.lang.NullPointerException'.
Caused by:
java.sql.SQLException: Java exception: ': java.lang.NullPointerException'.
at
org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.Util.javaException(Unknown Source)
at
org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown
Source)
at
org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown
Source)
at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown
Source)
at org.apache.derby.impl.jdbc.EmbedConnection.commit(Unknown Source)
at
org.apache.commons.dbcp.DelegatingConnection.commit(DelegatingConnection.java:238)
at
org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.commit(PoolingDataSource.java:199)
at
org.springframework.jdbc.datasource.DataSourceTransactionManager.doCommit(DataSourceTransactionManager.java:245)
at
org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:651)
at
org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:621)
at
org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:146)
at com.aaa.bbb.cccFactory$ddd.add(cccFactory.java:324)
at com.aaa.eee.fff.ggg.reload(ggg.java:44)
at com.aaa.eee.fff.ggg.startup(ggg.java:57)
at com.aaa.eee.fff.Start.startupEee(Start.java:170)
at com.aaa.eee.fff.Start.startup(Start.java:146)
at com.aaa.start.Starter.startup(Starter.java:264)
at com.aaa.start.Main.startup(Main.java:270)
at com.aaa.start.Main.main(Main.java:199)
Caused by: java.sql.SQLException: Java exception: ':
java.lang.NullPointerException'.
at
org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
at
org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown
Source)
... 21 more
Caused by: java.lang.NullPointerException
at
org.apache.derby.impl.store.access.btree.ControlRow.getControlRowForPage(Unknown
Source)
at org.apache.derby.impl.store.access.btree.ControlRow.get(Unknown
Source)
at org.apache.derby.impl.store.access.btree.ControlRow.get(Unknown
Source)
at
org.apache.derby.impl.store.access.btree.BTreePostCommit.purgeRowLevelCommittedDeletes(Unknown
Source)
at
org.apache.derby.impl.store.access.btree.BTreePostCommit.performWork(Unknown
Source)
at org.apache.derby.impl.store.raw.xact.Xact.postTermination(Unknown
Source)
at org.apache.derby.impl.store.raw.xact.Xact.completeCommit(Unknown
Source)
at org.apache.derby.impl.store.raw.xact.Xact.commit(Unknown Source)
at org.apache.derby.impl.store.raw.xact.Xact.commit(Unknown Source)
at org.apache.derby.impl.store.access.RAMTransaction.commit(Unknown
Source)
at
org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.doCommit(Unknown
Source)
at
org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.userCommit(Unknown
Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.commit(Unknown
Source)
... 15 more
and derby.log:
2008-01-28 08:26:36.148 GMT Thread[Main,5,main] (XID = 1888), (SESSIONID = 2),
(DATABASE = directory:myDB), (DRDAID = null), Executing prepared statement:
SELECT COUNT(*) FROM ZZZ WHERE nID IS NULL :End prepared statement
2008-01-28 08:26:36.150 GMT Thread[Main,5,main] (XID = 1888), (SESSIONID = 2),
(DATABASE = directory:myDB), (DRDAID = null), Committing
2008-01-28 08:26:36.188 GMT Thread[Main,5,main] (XID = 1888), (SESSIONID = 2),
(DATABASE = directory:myDB), (DRDAID = null), Cleanup action starting
2008-01-28 08:26:36.188 GMT Thread[Main,5,main] (XID = 1888), (SESSIONID = 2),
(DATABASE = directory:myDB), (DRDAID = null), Failed Statement is: null with 2
parameters begin parameter #1: 1 :end parameter begin parameter #2: 1 :end param
eter
java.lang.NullPointerException
at
org.apache.derby.impl.store.access.btree.ControlRow.getControlRowForPage(Unknown
Source)
at org.apache.derby.impl.store.access.btree.ControlRow.get(Unknown
Source)
at org.apache.derby.impl.store.access.btree.ControlRow.get(Unknown
Source)
at
org.apache.derby.impl.store.access.btree.BTreePostCommit.purgeRowLevelCommittedDeletes(Unknown
Source)
at
org.apache.derby.impl.store.access.btree.BTreePostCommit.performWork(Unknown
Source)
at org.apache.derby.impl.store.raw.xact.Xact.postTermination(Unknown
Source)
at org.apache.derby.impl.store.raw.xact.Xact.completeCommit(Unknown
Source)
at org.apache.derby.impl.store.raw.xact.Xact.commit(Unknown Source)
at org.apache.derby.impl.store.raw.xact.Xact.commit(Unknown Source)
at org.apache.derby.impl.store.access.RAMTransaction.commit(Unknown
Source)
at
org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.doCommit(Unknown
Source)
at
org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.userCommit(Unknown
Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.commit(Unknown
Source)
at org.apache.derby.impl.jdbc.EmbedConnection.commit(Unknown Source)
at
org.apache.commons.dbcp.DelegatingConnection.commit(DelegatingConnection.java:238)
at
org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.commit(PoolingDataSource.java:199)
at
org.springframework.jdbc.datasource.DataSourceTransactionManager.doCommit(DataSourceTransactionManager.java:245)
at
org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:651)
at
org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:621)
at
org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:146)
at com.aaa.bbb.cccFactory$ddd.add(cccFactory.java:324)
at com.aaa.eee.fff.ggg.reload(ggg.java:44)
at com.aaa.eee.fff.ggg.startup(ggg.java:57)
at com.aaa.eee.fff.Start.startupEee(Start.java:170)
at com.aaa.eee.fff.Start.startup(Start.java:146)
at com.aaa.start.Starter.startup(Starter.java:264)
at com.aaa.start.Main.startup(Main.java:270)
at com.aaa.start.Main.main(Main.java:199)
Cleanup action completed
This is a long transaction that has suddenly started throwing a NPE.
Nothing strange happens during the transaction, but on closing I get
the NPE.
If I reorder some of the statements in the transaction (keeping
functional equivalence) the NPE is sometimes not thrown.
I have already moved any table/index create statements to a different
(previously committed) transaction. (I have had a few NPE before and locking
issues that led me to this practice).
For a while I thought that shutting down derby after creating tables solved the
problem, but this has been proven false.
I have tried to run with a sane version, but then I am blocked by too many
DERBY-3360.
Also:
On occasion the transaction DOES commit. Or seems to, but then Derby becomes
unresponsive, the db files do not grow, but CPU rises and new connections can
connect but get no response to commands. I don't know if this is really
connected or not, but I thought I would mention it, as this unresponsive
problem is what I am supposed to be diagnosing. When I say seems to commit, I
mean that sometimes commit returns, sometimes it doesn't. Not very helpful, I
know.
