Re: [Exist-open] NullPointerException in org.exist.xquery.RootNode

[Wolfgang <wol...@ex...>]

> We would thus need to synchronize access to cachedDocs, but this
> seems much too expensive when compared to the benefits. I rather
> prefer to completely clear the cached fields. See my fix in rev 8200:
> 
> 
> http://exist.svn.sourceforge.net/exist/?rev=8200&view=rev

According to the second stack trace you sent me, my previous fix for the
concurrency issue (in rev 8200) wasn't sufficient. I could not reproduce 
the issue with a test, but I think we indeed need to synchronize access 
to the cached fields in LocationStep and some other query classes. I 
changed this and did run some tests to see if there's a measurable 
impact on query performance. So far, it all looks ok. The changes are here:

http://exist.svn.sourceforge.net/exist/?rev=8209&view=rev

Could you test this? As I said, I failed to create a test for the issue. 
I guess the timing between the concurrent threads needs to be very exact 
in order to provoke the bug.

Wolfgang