Another clue:

Exception in thread "Thread-1637" java.lang.IllegalMonitorStateException at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryRelease(ReentrantReadWriteLock.java:374) at java.util.concurrent.locks.AbstractQueuedSynchronizer.release(AbstractQueuedSynchronizer.java:1260) at java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.unlock(ReentrantReadWriteLock.java:1131) at org.basex.core.DBLocking.release(DBLocking.java:219) at org.basex.core.Context.unregister(Context.java:249) at org.basex.core.Command.execute(Command.java:104) at org.basex.core.Command.execute(Command.java:117) at org.basex.server.ClientListener.execute(ClientListener.java:384) at org.basex.server.ClientListener.add(ClientListener.java:355) at org.basex.server.ClientListener.run(ClientListener.java:100) Exception in thread "Thread-2277" java.lang.IllegalMonitorStateException at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryRelease(ReentrantReadWriteLock.java:374) at java.util.concurrent.locks.AbstractQueuedSynchronizer.release(AbstractQueuedSynchronizer.java:1260) at java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.unlock(ReentrantReadWriteLock.java:1131) at org.basex.core.DBLocking.release(DBLocking.java:219) at org.basex.core.Context.unregister(Context.java:249) at org.basex.core.Command.execute(Command.java:104) at org.basex.server.ClientListener.run(ClientListener.java:145)

This seems to be at the moment of freezing.

On Thu, Sep 18, 2014 at 9:41 AM, Gerald de Jong gerald@delving.eu wrote:

Ah I found out how to remove the lock from http://docs.basex.org/wiki/Transaction_Management. Just deleted the upd file.

After that and a restart it seems to be working again, but the reality is that it died on me. I still need clues to figure out why. Are there some tricks, like increasing memory or something, which will prevent it being overwhelmed? (if that's what happened).

On Wed, Sep 17, 2014 at 7:58 PM, Gerald de Jong gerald@delving.eu wrote:

...

Hello Folks,

Is there anything I can do when opening my database results in "Datbase blabla is being updated, or update was not completed."?

A program was pumping serious amounts of XML into BaseX with a few processes concurrently and then things seem to have gone haywire - big CPU usage for a long time but that's all. Nothing seems to tell me what's wrong, and now I don't know how to find out, or maybe hopefully repair.

I've killed the server, and now I just run bin/basex to look around. But it seems I can't even find out what went wrong.

I'd like to know what went on I can prevent this next time. Do you think the problem was too much concurrency, or not enough memory, or something else?

Any clues?

• Gerald

PS. My project is in Cultural Heritage. https://github.com/delving/narthex

-- Delving BV, Vasteland 8, Rotterdam http://www.delving.eu http://twitter.com/fluxe skype: beautifulcode +31629339805

-- Delving BV, Vasteland 8, Rotterdam http://www.delving.eu http://twitter.com/fluxe skype: beautifulcode +31629339805

Hi Christian,

The client code is tiny and is all based on the Java API (although it's in Scala). Even for people not familar with Scala it should be readable. I'm curious if somebody sees a fatal flaw or something that could be improved.

This is it:

def withSession[T](block: ClientSession => T): T = { val session = new ClientSession(host, port, user, pass) try { block(session) } finally { session.close() } }

def withDbSession[T](database: String)(block: ClientSession => T): T = { withSession { session => session.execute(new Open(database)) session.execute(new Set("autoflush", "false")) val result = block(session) session.execute(new Flush()) result } }

def add(database: String, path: String, document: String) = withDbSession(database)(_.add(path, new ByteArrayInputStream(document.getBytes("utf-8"))))

This add() function gets called about a million times, ha ha, literally.

Creating an SSCCE might be tricky for such a concurrency issue. I'll see if the crashing persists and maybe find a way to reproduce it if so.

I've really come to enjoy doing everything on the back end with XQuery/BaseX. Quite fun composing queries using Scala multi-line string interpolation.

def getIds(since: String): String = db { session => val q = s""" | | let $$records := collection('$recordDb')/narthex | return | <ids>{ | for $$narthex in $$records | where $$narthex/@mod >= ${quote(since)} | order by $$narthex/@mod descending | return | <id>{$$narthex/@mod}{string($$narthex/@id)}</id> | }</ids> | |""".stripMargin.trim session.query(q).execute() }

Gerald

Ah I found out how to remove the lock from

...

http://docs.basex.org/wiki/Transaction_Management. Just deleted the upd file.

After that and a restart it seems to be working again, but the reality is that it died on me. I still need clues to figure out why. Are there

some

...

tricks, like increasing memory or something, which will prevent it being overwhelmed? (if that's what happened).

It's difficult to say in general what may have causes the faulty behavior. You could check out the information stored in the database logs [1]. Maybe there was one particular query that caused the slowdown?

...

Exception in thread "Thread-1637" java.lang.IllegalMonitorStateException at

java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryRelease(ReentrantReadWriteLock.java:374)

...

at

java.util.concurrent.locks.AbstractQueuedSynchronizer.release(AbstractQueuedSynchronizer.java:1260)

...

at

java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.unlock(ReentrantReadWriteLock.java:1131)

...

at org.basex.core.DBLocking.release(DBLocking.java:219) at org.basex.core.Context.unregister(Context.java:249) at org.basex.core.Command.execute(Command.java:104) at org.basex.core.Command.execute(Command.java:117) at org.basex.server.ClientListener.execute(ClientListener.java:384) at org.basex.server.ClientListener.add(ClientListener.java:355) at org.basex.server.ClientListener.run(ClientListener.java:100)

This usually indicates that the client/server code is used in some unorthodox way. Do you think you can provide us with an SSCCE?

Thanks, Christian

[1] http://docs.basex.org/wiki/Logging