哪位大神知道这是什么错误

Exiting
/home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/binder.rb:255:in initialize': Address already in use - bind(2) for "localhost" port 3000 (Errno::EADDRINUSE)
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/binder.rb:255:innew'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/binder.rb:255:in add_tcp_listener'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/binder.rb:102:inblock in parse'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/binder.rb:85:in each'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/binder.rb:85:inparse'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/runner.rb:129:in load_and_bind'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/single.rb:84:inrun'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/puma/launcher.rb:172:in run'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/puma-3.4.0/lib/rack/handler/puma.rb:51:inrun'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/rack-2.0.1/lib/rack/server.rb:296:in start'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/railties-5.0.0/lib/rails/commands/server.rb:79:instart'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:90:in block in server'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:85:intap'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:85:in server'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:49:inrun_command!'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/railties-5.0.0/lib/rails/commands.rb:18:in <top (required)>'
from /home/guodong/RubymineProjects/project/demo/bin/rails:9:inrequire'
from /home/guodong/RubymineProjects/project/demo/bin/rails:9:in <top (required)>'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/spring-1.7.2/lib/spring/client/rails.rb:28:inload'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/spring-1.7.2/lib/spring/client/rails.rb:28:in call'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/spring-1.7.2/lib/spring/client/command.rb:7:incall'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/spring-1.7.2/lib/spring/client.rb:30:in run'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/spring-1.7.2/bin/spring:49:in'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/spring-1.7.2/lib/spring/binstub.rb:11:in load'
from /home/guodong/.rvm/gems/ruby-2.3.0/gems/spring-1.7.2/lib/spring/binstub.rb:11:in'
from /home/guodong/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in require'
from /home/guodong/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:inrequire'
from /home/guodong/RubymineProjects/project/demo/bin/spring:13:in <top (required)>'
from bin/rails:3:inload'
from bin/rails:3:in `'

端口已经被占用，是不是已经有一个程序在运行，上次运行的没有关闭，别的程序干扰或者防火墙阻止。

knabud大家的角度讲

Address already in use - bind(2) for "localhost" port 3000 (Errno::EADDRINUSE)；
端口地址3000已经被占用，试试换别的吧