Github user acton393 commented on the issue:
https://github.com/apache/incubator-weex/pull/1072
@xuyouyang Cases occurs to me that one of thread operating the storage and
then operating the fontFamilyDic, as they was in a same dictionary. And for
`os_unfair_lock`, this is not a type of recursive lock, so it can not be
acquired multi times.---
