gem install atomicしようとしたら入らなかった % sudo gem install atomic -v '1.1.16' Building native extensions. This could take a while... ERROR: Error installing atomic: ERROR: Failed to build gem native extension. /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb checking for libkern/OSAtomic.h... yes creating Makefile make "DESTDIR=" compiling atomic_reference.c atomic_reference.