线程安全的Rails

Thread Safe Rails？ 关于线程安全的Rails，请大家慎重采用，具体看这篇文章：http://m.onkey.org/thread-safety-for-your-rails。

 

上一个项目我们怀着战战兢兢的心情开启了多线程，结果是出乎意料得好。开启多线程后没遇到什么困难，可能会遇到的问题有两点：

 

1. 去掉class variable (当然，基本上你不应该使用类变量)

 

2. 另外一件事情，就是在multiple threads下面Rails需要eager load libs。请移步：http://gigix.thoughtworkers.org/2009/7/17/move-to-multi-threaded-rails

 

 

多线程的Rails对于performance有极大提升，请再次移步：http://blog.headius.com/2008/08/qa-what-thread-safe-rails-means.html   （请自行fan qiang）

 

基本上意思是内存使用量的锐减和数据库连接资源的优化:

 

写道

In a typical Mongrel setup, handling 10 concurrent requests means you have to have 10 copies of Rails loaded, 10 copies of your application loaded, 10 in-memory data caches, 10 database connections...everything has to be scaled in lock step for every additional request you want to handle concurrently.

 

写道

Instead of a single database connection for a given Rails instance, there will be a pool of connections, allowing N database connections to be used by the M requests executing concurrently. It also means allowing requests to potentially execute without consuming a connection, so the number of live, active connections usually will be lower than the number of requests you can handle concurrently.

 

References:

 

教程： http://m.onkey.org/2008/10/23/thread-safety-for-your-rails

Slides:  http://www.slideshare.net/Naoto.Takai/jruby-on-rails-and-thread-safety-presentation 
Q & A: http://stackoverflow.com/questions/647642/ruby-rails-thread-safety

 

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评论

2 楼 andyhu1007 2010-04-10  

robbin 写道

何况多进程rails都是每进程hold一个持久连接，数据库资源利用很充分，谈不上多线程能够节省，何况多线程调度连接池也有额外的开销和复杂度。

headius说道：

引用

It also means allowing requests to potentially execute without consuming a connection

potentially～～

1 楼 robbin 2010-04-10  

ruby本地的lib不是线程安全的，你多线程rails读取本地lib如果遇到阻塞调用整个进程会被全部挂起。

何况多进程rails都是每进程hold一个持久连接，数据库资源利用很充分，谈不上多线程能够节省，何况多线程调度连接池也有额外的开销和复杂度。

最后，多进程 vs 多线程 从性能，可扩展性和稳定性来说，多线程并没有什么优势。