How to fetch URLs in parallell with EventMachine a

How to fetch URLs in parallell with EventMachine and Ruby

How to fetch URLs in parallell with EventMachine and Ruby

Ruby posted 10 months ago by christian

Save time by doing things in parallell:

    1    require    ' rubygems '  
    2    require    ' eventmachine '  
    3    require    ' open-uri '  
    4    require    ' pp '  
    5    require    ' thread '  
    6    require    ' benchmark '  
    7   
    8    class   Worker 
    9      include   EM :: Deferrable 
   10   
   11      def   run 
   12       get_google
   13       set_deferred_status   : succeeded 
   14      end 
   15    end 
   16   
   17    def   get_google 
   18       #  sorry for spamming you 
   19      open (  ' http://www.google.com/ '  )  do  | f |
   20         # pp f.meta 
   21      end 
   22    end 
   23   
   24    def   asynchronous ( i )
   25     worker  =   Worker . new 
   26       #  on success 
   27     worker. callback   do 
   28       p   "   #{  Thread   .  current   }   done   #{ i }  ! "  
   29      end  
   30     worker. errback   do  
   31       p   " Unexpected error "      
   32        EM . stop   
   33      end 
   34       #  
   35      Thread . new   do 
   36       worker. run 
   37        EM . stop 
   38      end  
   39       # puts "scheduling done!" 
   40    end 
   41   
   42    def   synchronous ( i )
   43     get_google
   44    end 
   45   
   46     #  on error 
   47    EM . error_handler   do  | e |  
   48     p   " Unexpected error:   #{ e }   "   
   49    end 
   50   
   51    EM . run   do 
   52     seconds  =   Benchmark . realtime   do 
   53        50 . times   do  | i |
   54         asynchronous i
   55        end 
   56      end 
   57     p   " With EventMachine:   #{ seconds }   elapsed... "  
   58   
   59     seconds  =   Benchmark . realtime   do 
   60        50 . times   do  | i |
   61         synchronous i
   62        end 
   63      end 
   64     p   " Without EventMachine:   #{ seconds }   elapsed... "  
   65    end 

Output:

    1    With   EventMachine :  9.05974316596985  elapsed...
    2    Without   EventMachine :  19.1381118297577  elapsed...

Conclusion Speeds up blocking operations. EventMachine is currently limited to one CPU core (native thread) per process.

References http://ujihisa.blogspot.com/2009/08/try-eventmachine.html http://www.scribd.com/doc/21017871/Event-Machine-Presentation http://www.scribd.com/doc/25939580/Event-Machine

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