CODEWITHSUNDEEP
ruby-on-railsrubymultithreadingtimeout
user1130176
user1130176

Reputation: 1878

Ruby / Rails Timeout with threads - how to wait a while then rejoin later

I'm trying to run a process in a thread, and if it takes longer than x seconds, redirect to a waiting page and then do an ajax refresh

begin
    Timeout::timeout(10) do
        t = Thread.new do
            begin
                output = do_work
                session[:result] = "done"
            rescue Exception => e
                session[:result] = "exception"
            end
        end
        t.join
    end
    if session[:result] = "done"
        redirect_to :done
    else
        redirect_back fallback_location: :root, notice: 'Unable to process request, please try again.'
    end
rescue Exception => e
    if e.message == "execution expired"
        # this means the timeout fired, so send them to waiting
        redirect_to waiting_path
    else
        redirect_back fallback_location: :root, notice: 'Unable to process request, please try again.'
    end
end

then, in waiting, check for result

def waiting
    # session[:result] never updates
end

What am I doing wrong? I would expect that if the exception fires, the thread would survive, as evidenced by this simple experiment:

begin
    Timeout::timeout(1) do
        t = Thread.new do
            sleep(5)
            puts "done!"
        end
        t.join
    end
rescue Exception => e
    if e.message == "execution expired"
        # this means the timeout fired, so send them to waiting
        puts "expired!"
    end
end

The above code works fine, and after 5 seconds, the thread completes and shows the output.

Is this because you can't set the session in a thread, or something like this?

Thanks for any help, Kevin

Upvotes: 1

Views: 400

Answers (1)

Chandan
Chandan

Reputation: 11797

You could try passing the current binding to the thread as an argument:

Thread.new(binding) do 
    thread_session = eval("session", binding)
end

Note: I would suggest to use DelayedJob which is better way to handle a long-running process spun off from a user request?

Upvotes: 1

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