AssertionError in WildcardTypeImpl.getUpperBoundASTs

Dawid Weiss dawid.weiss at
Fri Oct 13 07:53:01 UTC 2017

Hi all,

We are observing very infrequent assertion errors originating in
getUpperBoundASTs, mostly during concurrent builds on our build
machine, when it's under a heavy load. This has been happening from
time to time with various Java versions; most recently with 1.8.0_131.

I don't see anything in Jira about it, but even a quick Google search
yields some hits [1].

The stack trace starts with (I include the jackson stack frame which calls it):

java.lang.AssertionError: null
at sun.reflect.generics.reflectiveObjects.WildcardTypeImpl.getUpperBoundASTs(
at sun.reflect.generics.reflectiveObjects.WildcardTypeImpl.getUpperBounds(
at com.fasterxml.jackson.databind.type.TypeFactory._fromWildcard(

The problem cannot be easily reproduced, but I see a comment mentioned
on the core-libs-dev a while ago [2] by Joel Borggrén-Franck, so
perhaps his question is a valid one and worth investigating:

> Btw, has anyone seen the assert for upper/lower bounds == null fail in the wild?


(note the "[JENKINS] Lucene-olr-master-Linux" hit).


More information about the core-libs-dev mailing list