Database corrupted on updating with RestXQ - BaseX-Talk - mailman.uni-konstanz.de

26 Jul 2019


      Hi all,
starting with 9.2.1 we experience a strange error with a RESTXQ API  of 
ours that we have been using for years.
The typical pattern is lookup a document update it and store it back.
We have done this milions of time and also all the tests work neatly.
But when using it from inside the web application, at around the tenth 
operation we get the DB corrupted with the stack trace [1]. This seems 
to happen only when the database is nearly empty and, for sure, it 
doesn't appear on 8.x series.
It feels like some concurrency flaw is introduced somewhere but it's 
hard to say because the API is eight years in age and it never changed 
significantly.
I know it's hard without an SSCE... but while working to insulate this 
byzantine behaviour (I've been trying for days now) maybe someone in the 
list has a clue or is able to interpret the stack trace?
Thanks and have a nice weekend,
Marco.
[1]
Improper use? Potential bug? Your feedback is welcome:
Contact: basex-talk@mailman.uni-konstanz.de
Version: BaseX 9.3 beta
Java: Ubuntu, 13
OS: Linux, amd64
Stack Trace:
java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
     at org.basex.io.random.TableDiskAccess.fpre(TableDiskAccess.java:507)
     at org.basex.io.random.TableDiskAccess.cursor(TableDiskAccess.java:468)
     at org.basex.io.random.TableDiskAccess.read1(TableDiskAccess.java:156)
     at org.basex.data.Data.kind(Data.java:304)
     at org.basex.query.value.node.DBNode.<init>(DBNode.java:50)
     at org.basex.query.value.seq.DBNodeSeq.get(DBNodeSeq.java:139)
     at org.basex.query.value.seq.DBNodeSeq.get(DBNodeSeq.java:164)
     at org.basex.query.func.db.DbOpen.value(DbOpen.java:19)
     at org.basex.query.func.StandardFunc.optimize(StandardFunc.java:82)
     at org.basex.query.expr.Arr.inline(Arr.java:69)
     at org.basex.query.expr.path.Path.inline(Path.java:962)
     at org.basex.query.expr.gflwor.ForLet.inline(ForLet.java:66)
     at org.basex.query.expr.gflwor.GFLWOR.inline(GFLWOR.java:804)
     at org.basex.query.expr.gflwor.GFLWOR.inlineLets(GFLWOR.java:339)
     at org.basex.query.expr.gflwor.GFLWOR.optimize(GFLWOR.java:106)
     at org.basex.query.expr.gflwor.GFLWOR.inline(GFLWOR.java:785)
     at org.basex.query.expr.Try.inline(Try.java:106)
     at org.basex.query.expr.gflwor.GFLWOR.inline(GFLWOR.java:816)
     at org.basex.query.expr.gflwor.GFLWOR.inlineLets(GFLWOR.java:339)
     at org.basex.query.expr.gflwor.GFLWOR.optimize(GFLWOR.java:106)
     at org.basex.query.func.StaticFunc.inline(StaticFunc.java:294)
     at org.basex.query.func.StaticFuncCall.compile(StaticFuncCall.java:67)
     at org.basex.query.scope.MainModule.comp(MainModule.java:81)
     at org.basex.query.QueryCompiler.compile(QueryCompiler.java:114)
     at org.basex.query.QueryCompiler.compile(QueryCompiler.java:105)
     at org.basex.query.QueryContext.compile(QueryContext.java:312)
     at org.basex.query.QueryContext.iter(QueryContext.java:331)
     at 
org.basex.http.restxq.RestXqResponse.serialize(RestXqResponse.java:73)
     at org.basex.http.web.WebResponse.create(WebResponse.java:63)
     at org.basex.http.restxq.RestXqServlet.run(RestXqServlet.java:53)
     at org.basex.http.BaseXServlet.service(BaseXServlet.java:65)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
     at 
org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:865)
     at 
org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:542)
     at 
org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:146)
     at 
org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
     at 
org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
     at 
org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:257)
     at 
org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1700)
     at 
org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255)
     at 
org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1345)
     at 
org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203)
     at 
org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:480)
     at 
org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1667)
     at 
org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201)
     at 
org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1247)
     at 
org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144)
     at 
org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
     at org.eclipse.jetty.server.Server.handle(Server.java:505)
     at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:370)
     at 
org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:267)
     at 
org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:305)
     at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
     at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117)
     at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:333)
     at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:310)
     at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:168)
     at 
org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:126)
     at 
org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:366)
     at 
org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:698)
     at 
org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:804)
     at java.base/java.lang.Thread.run(Thread.java:835)