用rvm下载的ruby
bundle exec rackup之后报错，报错内容如下
/home/johanna/.rvm/gems/ruby-2.2.2/gems/ffi-1.9.18/lib/ffi/library.rb:147:in `block in ffi_lib': Could not open library '/home/johanna/twenty-fifty/model/libmodel.so': /home/johanna/twenty-fifty/model/libmodel.so: cannot open shared object file: No such file or directory (LoadError)
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/ffi-1.9.18/lib/ffi/library.rb:100:in `map'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/ffi-1.9.18/lib/ffi/library.rb:100:in `ffi_lib'
from /home/johanna/twenty-fifty/model/model.rb:102:in `<module:C>'
from /home/johanna/twenty-fifty/model/model.rb:100:in `<class:Model>'
from /home/johanna/twenty-fifty/model/model.rb:4:in `<top (required)>'
from /home/johanna/twenty-fifty/model/data_from_model.rb:1:in `require_relative'
from /home/johanna/twenty-fifty/model/data_from_model.rb:1:in `<top (required)>'
from /home/johanna/twenty-fifty/src/server.rb:6:in `require_relative'
from /home/johanna/twenty-fifty/src/server.rb:6:in `<top (required)>'
from /home/johanna/twenty-fifty/config.ru:7:in `require'
from /home/johanna/twenty-fifty/config.ru:7:in `block in <main>'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/builder.rb:55:in `instance_eval'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/builder.rb:55:in `initialize'
from /home/johanna/twenty-fifty/config.ru:in `new'
from /home/johanna/twenty-fifty/config.ru:in `<main>'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/builder.rb:49:in `eval'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/builder.rb:49:in `new_from_string'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/builder.rb:40:in `parse_file'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/server.rb:319:in `build_app_and_options_from_config'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/server.rb:219:in `app'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/server.rb:354:in `wrapped_app'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/server.rb:283:in `start'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/lib/rack/server.rb:148:in `start'
from /home/johanna/.rvm/gems/ruby-2.2.2/gems/rack-2.0.3/bin/rackup:4:in `<top (required)>'
from /home/johanna/.rvm/gems/ruby-2.2.2/bin/rackup:23:in `load'
from /home/johanna/.rvm/gems/ruby-2.2.2/bin/rackup:23:in `<main>'
from /home/johanna/.rvm/gems/ruby-2.2.2/bin/ruby_executable_hooks:22:in `eval'
from /home/johanna/.rvm/gems/ruby-2.2.2/bin/ruby_executable_hooks:22:in `<main>'
可能是ruby版本的问题，但是未找到解决办法
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