$ gem install ref libv8 therubyracer
Fetching: ref-1.0.2.gem (100%)
Successfully installed ref-1.0.2
Installing ri documentation for ref-1.0.2
Done installing documentation for ref (0 sec).
Fetching: libv8-3.11.8.13.gem (100%)
Building native extensions.  This could take a while...
Successfully installed libv8-3.11.8.13
unable to convert "\x90" from ASCII-8BIT to UTF-8 for vendor/v8/out/x64.release/process, skipping
unable to convert "\xC0" from ASCII-8BIT to UTF-8 for vendor/v8/out/x64.release/mksnapshot, skipping
unable to convert "\xC0" from ASCII-8BIT to UTF-8 for vendor/v8/out/x64.release/lineprocessor, skipping
unable to convert "\xA0" from ASCII-8BIT to UTF-8 for vendor/v8/out/x64.release/d8, skipping
unable to convert "\xF8" from ASCII-8BIT to UTF-8 for vendor/v8/out/x64.release/cctest, skipping
unable to convert "\xEC" from ASCII-8BIT to UTF-8 for vendor/v8/out/x64.release/preparser, skipping
unable to convert "\xA0" from ASCII-8BIT to UTF-8 for vendor/v8/out/x64.release/shell, skipping
Installing ri documentation for libv8-3.11.8.13
Done installing documentation for libv8 (100 sec).
Fetching: therubyracer-0.11.3.gem (100%)
Building native extensions.  This could take a while...
Successfully installed therubyracer-0.11.3
Installing ri documentation for therubyracer-0.11.3
Done installing documentation for therubyracer (0 sec).
3 gems installed

新手启动这个服务，有这个警告，跳过了，不知道对后面有影响没？