[hibernate-dev] Missing transaction hangs the testsuite

Steve Ebersole steve at hibernate.org
Fri Jul 17 12:14:55 EDT 2015 

Process != test.  Process here == connection.  You have multiple.

On Fri, Jul 17, 2015, 11:12 AM Sanne Grinovero <sanne at hibernate.org> wrote:

> On 17 July 2015 at 16:25, Steve Ebersole <steve at hibernate.org> wrote:
> > It would seem that this is a regression with ORM, I agree.  However, we
> do
> > not know how recent of a regression.  And that is the problem.  We have
> no
> > idea how far back to look.  Because the ORM CI jobs against MySQL,
> > PostrgreSQL, Oracle, etc have not been running for many months.  IIRC
> even
> > when they were running on the old CI servers we had problems with those
> jobs
> > that were not looked at for some time.
>
> Sure, same problem here: not run these tests for months, and you're
> right I could do a quick check on a slightly older branch which is
> using ORM 4.3 and I have the same problem.
>
> > As far as what you see, I am not convinced it is what you think it is in
> > terms of auto-commit for queries run outside of a transaction.  This part
> > has not changed in 5.0.  Assuming you are using the "built in Connection
> > pool", there is a setting that controls the auto-commit mode of the
> > connections we create (hibernate.connection.autocommit).  That setting
> has
> > always been there, and it has always defaulted to false.  This has not
> > changed.  In fact the same exact code is used in 4.3 and 5.0 for creating
> > these Connections:
> > org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.
> The
> > autoCommit value in there comes from the setting I just mentioned.  The
> > logical outcome is the same even before 4.3, just that it was done
> > differently.  So bottom line, if you are not seeing auto-commit on these
> > Connections now, you never were.  Now it is possible that their are some
> > ancillary changes that cause the lack of auto-commit to now be an issue
> > where it was not before.  So first, I'd need to know whether the
> Connection
> > here is auto-commit or is not.  From there we can start drilling down on
> > what might be a cause.  But keep in mind too, that with hangs and
> deadlocks
> > the process that hangs is often not the culprit; often it is the previous
> > process that is holding locks that is the culprit.
>
> I understand, but in this specific case I can reproduce the issue by
> running a single test.
> Also that psql SQL I shared clearly shows which statement is causing it to
> hang,
> and I could fix the test by just wrapping that statement in a transaction.
>
> >
> > My case is actually different, at least on the surface.  Mine happens on
> > dropping tables after the test is complete (for MySQL anyway).  Which
> got me
> > to looking at schema export and friends and how they handle connections.
> > They handle connections quite differently.  Again the same as they used
> to,
> > but I mean very different from how sessions manage connections.  In
> schema
> > export the connections are always set to auto-commit mode at the start of
> > processing.  Then they never do anything with auto-commit afterwards.  I
> am
> > not sure this is right.
>
> Actually it sounds like you're having the same problem. I debugged the
> PosgreSQL tests first, but I had the same on MySQL (as in the
> stacktrace I shared),
> and the test also hangs on schema drop.
> The problem is that the schema can't be dropped because a previous
> statement - from a session which is now correctly closed - is still
> holding locks.
>
> Thanks,
> Sanne
>
> >
> >
> >
> >
> > On Fri, Jul 17, 2015 at 3:51 AM Sanne Grinovero <sanne at hibernate.org>
> wrote:
> >>
> >> Thanks Steve, I wasn't sure if I had found a problem.
> >> Still, it looks like the Hibernate Search tests are not benefiting
> >> from auto-commit, or I wouldn't have this problem right? Our testing
> >> configuration properties have been the same for years and I'm just
> >> re-enabling tests which haven't been run for a while, so I suspect
> >> something changed in ORM.
> >>
> >> I think I'd expect Hibernate ORM to automatically enable auto-commit
> >> on operations not running within a transaction, to make sure all locks
> >> are released when the Session is closed.
> >>
> >> Thanks,
> >> Sanne
> >>
> >> On 17 July 2015 at 00:14, Steve Ebersole <steve at hibernate.org> wrote:
> >> > For what it is worth, I am running into the same problems on MySQL for
> >> > the
> >> > ORM tests in terms of blocks on dropping tables.  PGSQL at least
> >> > finishes,
> >> > although I run into 55 errors which I still need to triage.
> >> >
> >> > On Thu, Jul 16, 2015 at 5:59 PM Steve Ebersole <steve at hibernate.org>
> >> > wrote:
> >> >>
> >> >> There is really nothing to improve.  What would you suggest as an
> >> >> improvement?  I mean from a ORM perspective, we have an ato-commit
> >> >> Connection (presumably) and run a query.  How on earth would we know
> to
> >> >> expect that the database is holding locks for that?
> >> >>
> >> >> As far as "requiring transactions" I have tried to fly that plane
> >> >> multiple
> >> >> times in the past.  I think it is absolutely ridiculous to allow
> these
> >> >> auto-commit use cases.  In fact I personally wanted to take it to the
> >> >> more
> >> >> extreme case of always using JTA and simply mimicking "single
> resource
> >> >> JTA
> >> >> transactions" internally in the "JDBC transaction" case.  Gavin and I
> >> >> both
> >> >> did in fact.  But we got a lot of push back.
> >> >>
> >> >> So I am not sure exactly what the improvement here might be.  What is
> >> >> it
> >> >> you were thinking specifically?
> >> >>
> >> >> On Thu, Jul 16, 2015 at 5:36 PM Sanne Grinovero <sanne at hibernate.org
> >
> >>
> >> >> wrote:
> >> >>>
> >> >>> I finally got to re-enable MariaDB and PostgreSQL based tests for
> >> >>> Hibernate Search - which has been running on H2 only for some
> months -
> >> >>> and had to debug a case of a single test hanging for a long time.
> >> >>>
> >> >>> Essentially it would block - for hours - on the
> SessionFactory#close()
> >> >>> method, attempting to drop the database schema with the following
> >> >>> statement:
> >> >>>   > alter table AncientBook_alternativeTitles drop constraint
> >> >>> FKn8hhkmhof1mdgc4oi77ccq989
> >> >>>
> >> >>> Dumping threads I would get a very similar stack trace on both
> >> >>> databases; initially I thought someone had copy/pasted a socket
> >> >>> handling bug from one JDBC driver to the other ;-)
> >> >>>
> >> >>> The PostgreSQL testsuite hanging:
> >> >>>
> >> >>> "main" prio=10 tid=0x00007f0f40009000 nid=0x5f7c runnable
> >> >>> [0x00007f0f48956000]
> >> >>>    java.lang.Thread.State: RUNNABLE
> >> >>> at java.net.SocketInputStream.socketRead0(Native Method)
> >> >>> at java.net.SocketInputStream.read(SocketInputStream.java:152)
> >> >>> at java.net.SocketInputStream.read(SocketInputStream.java:122)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:145)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:114)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:73)
> >> >>> at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:274)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1660)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:257)
> >> >>> - locked <0x00000007c11e3860> (a
> >> >>> org.postgresql.core.v3.QueryExecutorImpl)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:500)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:374)
> >> >>> at
> >> >>>
> >> >>>
> org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:302)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.tool.hbm2ddl.DatabaseExporter.export(DatabaseExporter.java:47)
> >> >>> at
> >> >>>
> org.hibernate.tool.hbm2ddl.SchemaExport.perform(SchemaExport.java:476)
> >> >>> at
> >> >>>
> org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:430)
> >> >>> at
> org.hibernate.tool.hbm2ddl.SchemaExport.drop(SchemaExport.java:375)
> >> >>> at
> org.hibernate.tool.hbm2ddl.SchemaExport.drop(SchemaExport.java:371)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.internal.SessionFactoryImpl.close(SessionFactoryImpl.java:1069)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.search.test.util.FullTextSessionBuilder.close(FullTextSessionBuilder.java:149)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.search.test.util.FullTextSessionBuilder$1.evaluate(FullTextSessionBuilder.java:248)
> >> >>> at org.junit.rules.RunRules.evaluate(RunRules.java:20)
> >> >>> at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)
> >> >>>
> >> >>> The MariaDB testsuite hanging:
> >> >>>
> >> >>> "main" prio=10 tid=0x00007f8ca0009000 nid=0x4043 runnable
> >> >>> [0x00007f8ca5f5c000]
> >> >>>    java.lang.Thread.State: RUNNABLE
> >> >>> at java.net.SocketInputStream.socketRead0(Native Method)
> >> >>> at java.net.SocketInputStream.read(SocketInputStream.java:152)
> >> >>> at java.net.SocketInputStream.read(SocketInputStream.java:122)
> >> >>> at
> >> >>>
> >> >>>
> com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)
> >> >>> at
> >> >>>
> >> >>>
> com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)
> >> >>> at
> >> >>>
> >> >>>
> com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)
> >> >>> - locked <0x00000007c0baa518> (a
> >> >>> com.mysql.jdbc.util.ReadAheadInputStream)
> >> >>> at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2499)
> >> >>> at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2952)
> >> >>> at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2941)
> >> >>> at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3489)
> >> >>> at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1959)
> >> >>> at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2113)
> >> >>> at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2562)
> >> >>> - locked <0x00000007c0baa850> (a java.lang.Object)
> >> >>> at
> com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1664)
> >> >>> - locked <0x00000007c0baa850> (a java.lang.Object)
> >> >>> at
> com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1583)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.tool.hbm2ddl.DatabaseExporter.export(DatabaseExporter.java:47)
> >> >>> at
> >> >>>
> org.hibernate.tool.hbm2ddl.SchemaExport.perform(SchemaExport.java:476)
> >> >>> at
> >> >>>
> org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:430)
> >> >>> at
> org.hibernate.tool.hbm2ddl.SchemaExport.drop(SchemaExport.java:375)
> >> >>> at
> org.hibernate.tool.hbm2ddl.SchemaExport.drop(SchemaExport.java:371)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.internal.SessionFactoryImpl.close(SessionFactoryImpl.java:1069)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.search.test.util.FullTextSessionBuilder.close(FullTextSessionBuilder.java:149)
> >> >>> at
> >> >>>
> >> >>>
> org.hibernate.search.test.util.FullTextSessionBuilder$1.evaluate(FullTextSessionBuilder.java:248)
> >> >>> at org.junit.rules.RunRules.evaluate(RunRules.java:20)
> >> >>> at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
> >> >>> at
> >> >>>
> >> >>>
> org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)
> >> >>>
> >> >>> On Gail's suggestion I went looking for database level locks; I
> hadn't
> >> >>> thought of that as I assumed it would have timed out more
> aggressively
> >> >>> rather than have me wait for hours.
> >> >>> It turns out she was right and the reason for blocking was a simple
> >> >>> "count *" query being run as a post-test assertion, which we had
> >> >>> forgotten to wrap in an "open transaction & commit" statements pair.
> >> >>> The test assertion would be successful, but apparently it would hold
> >> >>> on the table lock beyond closing the Session and, then fail to drop
> >> >>> the database at the teardown of the test.
> >> >>>
> >> >>> I'm wondering if this is expected, or if there's something in the
> new
> >> >>> transaction handling code which could be improved? It took me
> several
> >> >>> hours to figure this out; maybe I'm just not using ORM as frequently
> >> >>> as once :)
> >> >>> If it's this critical to have the transaction, maybe it should be
> >> >>> mandatory?
> >> >>>
> >> >>> And as a memo for next time, this is the query to figure out details
> >> >>> about locks on our testing db:
> >> >>>  > SELECT * FROM pg_locks pl LEFT JOIN pg_stat_activity psa ON
> pl.pid
> >> >>> = psa.pid where datname = 'testingdb';
> >> >>>
> >> >>> Thanks,
> >> >>> Sanne
> >> >>> _______________________________________________
> >> >>> hibernate-dev mailing list
> >> >>> hibernate-dev at lists.jboss.org
> >> >>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>

More information about the hibernate-dev mailing list