Symptom:

unbound fails when running with multiple threads and linked against a version of libev ( http://software.schmorp.de/pkg/libev.html)

The error is: 

(libev) port_getn (see http://bugs.opensolaris.org/view_bug.do?bug_id=6268715, try LIBEV_FLAGS=3 env variable): Timer expired
Abort

Problem:

This is an issue with older version of the Solaris 10 system on x86 platform. See http://bugs.opensolaris.org/view_bug.do?bug_id=6268715

It has been fixed in recent versions of Solaris 10/OpenSolaris 

Solution

If this issue occurs, set the libev method "3" with

export LIBEV_FLAGS=3

before starting unbound.