From: Louis-Philippe <default@...>
Date: 2009-02-17T07:19:42+09:00
Subject: Re: Ruby Threading question Creating 4 threads

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and looking at it more, I think it would be better to leave the less stuff
in the mutex block as possible,
making it something something like:

mu.synchronize do
       job = $jobs.pop
end

puts "Checking for #{job}"
#Exit our thread if we have no more jobs to check
puts "No more jobs" and Thread.exit if job.nil?

I guess the Thread.exit could have caused a deadlock if inside the mutex,
and since the mutex locks your other threads you better keep it as small as
possible for efficiency sake.

2009/2/16 Louis-Philippe <default@spiralix.org>

> what if you put your thread body in an infinite loop, something like:
>
> Thread.new do
>   loop do
>     puts "Thread #{c} created"
>      job = nil
>
>      mu.synchronize do
>        job = $jobs.pop
>        puts "Checking for #{job}"
>        #Exit our thread if we have no more jobs to check
>        puts "No more jobs" and Thread.exit if job.nil?
>      end
>
>      t = count_files(job)
>      mu.synchronize { total += t }
>   end
> end
>
> and as you may have noticed, I replaced the 'return' statement inside your
> thread with a 'Thread.exit' method.
> I think it would be the right way to do it...
>
> 2009/2/16 <tristin.colby@gmail.com>
>
> Newbie Question:
>>
>> I have some code where I create 4 threads that pop elements off an
>> array and process them.  The problem is that each thread only pops off
>> one element, processes it, then returns; they don't continue to
>> process until the entire array is consumed.
>>
>> <code>
>> $jobs = %w[a b c d e f g]
>> def simulate_cleanup
>>
>>  puts "Checking for #{$jobs.length} jobs in /mnt/gen1/focal/temp"
>>  threads = []
>>
>>  mu = Mutex.new
>>  total = 0
>>
>>  1.upto(4) do |c|
>>     threads << Thread.new do
>>      puts "Thread #{c} created"
>>      job = nil
>>
>>      mu.synchronize do
>>        job = $jobs.pop
>>        puts "Checking for #{job}"
>>        #Exit our thread if we have no more jobs to check
>>        puts "No more jobs" and return if job.nil?
>>      end
>>
>>      t = count_files(job)
>>      mu.synchronize { total += t }
>>    end
>>  end
>>  threads.each { |t| t.join }
>>
>>  puts "Reduced by #{total} files"
>> end
>>
>> Example of output:
>> Thread 1 created
>> Thread 2 created
>> Thread 3 created
>> Thread 4 created
>> Checking for a
>> Checking for b
>> Checking for c
>> Checking for d
>>
>>
>>
>

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