On 9 Mar 2011, at 17:47, Chad Johnson <[email protected]> wrote:
> Let's say I have the following threading in my Rails web application:
>
> class MyController
> def my_action
> count = 0
> arr = []
>
> 10.times do |i|
> arr[i] = Thread.new {
> sleep(rand(0)/10.0)
> Thread.current["mycount"] = count
> count += 1
> }
> end
This looks thread dangerous to me - i don't think += is atomic.
>
> arr.each {|t| t.join; print t["mycount"], ", " }
> puts "count = #{count}"
> end
> end
>
> As you can see, the 'count' variable is shared across all threads.
>
> **Now,** what I want to do is **share 'count'** across multiple httpd
> requests and **allow my_action in MyController to have access to that
> variable**. For instance, maybe whatever spawns the ruby process to
> serve httpd process could hold the variable count in its scope, and then
> the ruby processes spawned for httpd processes could then access that
> variable.
>
> Using memcached, a database, and session variables is out of the
> question. Ultimately 'count' will actually be a resource object...an FTP
> connection.
>
> Is this possible?
I wouldn't go down this road if I were you. For starters presumably the objects
in question will be modified by those workers, you'll need to synchronise
access to them etc. You might also be painting yourself into a corner for the
day you need to scale beyond 1 server.
Personally, if I had to do this, I'd these objects in a separate long-lived
process (or processes) and have your controller actions talk to these processes
(exactly how depends on what you'll be doing, you might consider drb, message
queues etc)
Fred
> Perhaps using Apache/Passenger workers like at
> http://stackoverflow.com/questions/4471680/a-way-to-access-common-ftp-connection-resource-pool-in-ruby-across-ajax-calls/4471758#4471758?
>
> Example code would be appreciated.
>
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