Unicorn是一个Unix和局域网/本地主机优化的HTTP服务器。它充分利用功能的独有类Unix操作系统。它将人工回收，并重新启动应用程序的进程，也可以自己来管理多个进程。">负载均衡由操作系统内核来完成。服务器并不担心你的应用程序是线程是否安全，作为人工处理独立运行在自己的地址空间，对应每一个客户端。支持所有Rack的应用以及pre-Ruby版本，通过Ruby的安装包装上的Rails。它还支持原子日志循环，nginx的风格二进制重新执行，而不会失去连接，before_fork和after_fork挂钩，和可选的副本上友好的内存管理。
Unicorn 4.0.0更新日志：
A single Unicorn instance may manage more than 1024 workers
without needing privileges to modify resource limits. As a
result of this, the "raindrops"[1] gem/library is now a required
dependency.
TCP socket defaults now favor low latency to mimic UNIX domain
socket behavior (tcp_nodelay: true, tcp_nopush: false). This
hurts throughput, users who want to favor throughput should
specify "tcp_nodelay: false, tcp_nopush: true" in the listen
directive.
Error logging is more consistent and all lines should be
formatted correctly in backtraces. This may break the
behavior of some log parsers.
The call stack is smaller and thus easier to examine backtraces
when debugging Rack applications.
There are some internal API changes and cleanups, but none that
affect applications designed for Rack. See "git log v3.7.0.."
for details.
For users who cannot install kgio[2] or raindrops, Unicorn 1.1.x
remains supported indefinitely. Unicorn 3.x will remain
supported if there is demand. We expect raindrops to introduce
fewer portability problems than kgio did, however.
更新详细内容请参阅：http://unicorn.bogomips.org/ChangeLog.html
下载地址：http://bogomips.org/unicorn.git/snapshot/unicorn-4.0.0.tar.gz