This problem occurs when using older, non-hotspot versions
of the JDK. The error looks typically like:
Exception in thread "main" java.lang.UnsatisfiedLinkError: /usr/lib/libchm_java.so: /usr/lib/libchm_java.so: undefined symbol: pthread_join
The issue is that the old, non-hotspot versions of Java are not
linked against the POSIX threads library. Just switch to a more
recent version of the hotspot JDK and you will avoid this problem.