### Resque:

Pros:

* does not require thread safety (works with pretty much any gem out there);
* &lt;s&gt;has no interpreter preference (you can use any ruby);&lt;/s&gt;  
  [Resque currently supports MRI 2.3.0 or later](https://github.com/resque/resque/blob/master/README.markdown)
* loads of plugins.

Cons

* runs a process per worker (uses more memory);
* does not retry jobs (out of the box, anyway).

### Sidekiq:

Pros

* runs thread per worker (uses much less memory);
* less forking (works faster);
* more options out of the box.

Cons

* **[huge]** requires thread-safety of your code and **all dependencies**. If you run thread-unsafe code with threads, you&#39;re asking for trouble;
* works on some rubies better than others (jruby is recommended, efficiency on MRI is decreased due to GVL (global VM lock)).

From the question:

&gt; In particular I would like to know is there a way to monitor
&gt; programmatically whether a job is completed in sidekiq

Here&#39;s a solution for that:

 1. [Sidekiq::Status gem][1]
 2. Batch API (Sidekiq Pro) - [usage][2]


  [1]: https://github.com/utgarda/sidekiq-status
  [2]: https://github.com/mperham/sidekiq/issues/536

I need to get a response back in plain text from a ASP.NET Web API controller.

I have tried do a request with `Accept: text/plain` but it doesn&#39;t seem to do the trick.
Besides, the request is external and out of my control. What I would accomplish is to mimic the old ASP.NET way:

    context.Response.ContentType = &quot;text/plain&quot;;
    context.Response.Write(&quot;some text);

Any ideas?


*EDIT, solution*:
Based on Aliostad&#39;s answer, I added the [WebAPIContrib][1] text formatter, initialized it in the Application_Start:

      config.Formatters.Add(new PlainTextFormatter());

and my controller ended up something like:

    [HttpGet, HttpPost]
    public HttpResponseMessage GetPlainText()
    {
      return ControllerContext.Request.CreateResponse(HttpStatusCode.OK, &quot;Test data&quot;, &quot;text/plain&quot;);
    }


  [1]: http://nuget.org/packages/WebAPIContrib

Is there a way to force ASP.NET Web API to return plain text?

Does `java.util.List.isEmpty()` check if the list itself is `null`, or do I have to do this check myself?

For example:

    List&lt;String&gt; test = null;

    if (!test.isEmpty()) {
        for (String o : test) {
            // do stuff here			
        }
    }


Will this throw a `NullPointerException` because test is `null`?

Does java.util.List.isEmpty() check if the list itself is null?

I am currently using `Resque` for my background process but recently I heard a lot of huff-buff about `sidekiq`. Could anybody compare/differentiate? 

In particular I would like to know is there a way to monitor programmatically whether a job is completed in `sidekiq`

Resque vs Sidekiq?

<p>I am currently using <code>Resque</code> for my background process but recently I heard a lot of huff-buff about <code>sidekiq</code>. Could anybody compare/differentiate?</p>
<p>In particular I would like to know is there a way to monitor programmatically whether a job is completed in <code>sidekiq</code></p>


I know that when using `gem install`, the gem will be stored under /home/username/.rvm/gems/, under which gemset the gem was installed.

But if I use Bundler and specify the gem in the Gemfile, when I run bundle install, where will those gems be stored? And what if I already installed the gem using `gem install`, if I run bundle install, will it use the previous gem installed using `gem install`?

Where does bundler store gems?

I&#39;m defining a custom Exception on a model in rails as kind of a wrapper Exception: (`begin[code]rescue[raise custom exception]end`)

When I raise the Exception, I&#39;d like to pass it some info about a) the instance of the model whose internal functions raise the error, and b) the error that was caught.

This is going on an automated import method of a model that gets populated by POST request to from foreign datasource.

tldr; How can one pass arguments to an Exception, given that you define the Exception yourself? I have an initialize method on that Exception but the `raise` syntax seems to only accept an Exception class and message, no optional parameters that get passed into the instantiation process.

Raise custom Exception with arguments

##**Disclaimer**
I know that artificial benchmarks are evil. They can show results only for very specific narrow situation. I don&#39;t assume that one language is better than the other because of the some stupid bench. However I wonder why results is so different. Please see my questions at the bottom.

##Math benchmark description

Benchmark is simple math calculations to find pairs of prime numbers which differs by 6 (so called [sexy primes][1])
E.g. sexy primes below 100 would be: `(5 11) (7 13) (11 17) (13 19) (17 23) (23 29) (31 37) (37 43) (41 47) (47 53) (53 59) (61 67) (67 73) (73 79) (83 89) (97 103)`

##Results table

*In table: calculation time  in seconds*
Running: all except Factor was running in VirtualBox (Debian unstable amd64 guest, Windows 7 x64 host)
CPU: AMD A4-3305M

      Sexy primes up to:        10k      20k      30k      100k               
    
      Bash                    58.00   200.00     [*1]      [*1]
    
      C                        0.20     0.65     1.42     15.00
    
      Clojure1.4               4.12     8.32    16.00    137.93

      Clojure1.4 (optimized)   0.95     1.82     2.30     16.00
    
      Factor                    n/a      n/a    15.00    180.00

      Python2.7                1.49     5.20    11.00       119     
    
      Ruby1.8                  5.10    18.32    40.48    377.00
    
      Ruby1.9.3                1.36     5.73    10.48    106.00
    
      Scala2.9.2               0.93     1.41     2.73     20.84

      Scala2.9.2 (optimized)   0.32     0.79     1.46     12.01

[*1] - I&#39;m afraid to imagine how much time will it take&lt;br&gt;

##Code listings

C:

    int isprime(int x) {
      int i;
      for (i = 2; i &lt; x; ++i)
        if (x%i == 0) return 0;
      return 1;
    }

    void findprimes(int m) {
      int i;
      for ( i = 11; i &lt; m; ++i)
        if (isprime(i) &amp;&amp; isprime(i-6))
          printf(&quot;%d %d\n&quot;, i-6, i);
    }

    main() {
        findprimes(10*1000);
    }

Ruby:

    def is_prime?(n)
      (2...n).all?{|m| n%m != 0 }
    end

    def sexy_primes(x)
      (9..x).map do |i|
        [i-6, i]
      end.select do |j|
        j.all?{|j| is_prime? j}
      end
    end

    a = Time.now
    p sexy_primes(10*1000)
    b = Time.now
    puts &quot;#{(b-a)*1000} mils&quot;

Scala:

    def isPrime(n: Int) =
      (2 until n) forall { n % _ != 0 }

    def sexyPrimes(n: Int) = 
      (11 to n) map { i =&gt; List(i-6, i) } filter { _ forall(isPrime(_)) }

    val a = System.currentTimeMillis()
    println(sexyPrimes(100*1000))
    val b = System.currentTimeMillis()
    println((b-a).toString + &quot; mils&quot;)

Scala opimized `isPrime` (the same idea like in Clojure optimization):

    import scala.annotation.tailrec

    @tailrec // Not required, but will warn if optimization doesn&#39;t work
    def isPrime(n: Int, i: Int = 2): Boolean = 
      if (i == n) true 
      else if (n % i != 0) isPrime(n, i + 1)
      else false

Clojure:

    (defn is-prime? [n]
      (every? #(&gt; (mod n %) 0)
        (range 2 n)))

    (defn sexy-primes [m]
      (for [x (range 11 (inc m))
            :let [z (list (- x 6) x)]
            :when (every? #(is-prime? %) z)]
          z))

    (let [a (System/currentTimeMillis)]
      (println (sexy-primes (* 10 1000)))
      (let [b (System/currentTimeMillis)]
        (println (- b a) &quot;mils&quot;)))

Clojure optimized `is-prime?`:

    (defn ^:static is-prime? [^long n]
      (loop [i (long 2)] 
        (if (= (rem n i) 0)
          false
          (if (&gt;= (inc i) n) true (recur (inc i))))))
    
Python

    import time as time_

    def is_prime(n):
      return all((n%j &gt; 0) for j in xrange(2, n))

    def primes_below(x):
      return [[j-6, j] for j in xrange(9, x+1) if is_prime(j) and is_prime(j-6)]

    a = int(round(time_.time() * 1000))
    print(primes_below(10*1000))
    b = int(round(time_.time() * 1000))
    print(str((b-a)) + &quot; mils&quot;)

Factor

    MEMO:: prime? ( n -- ? )
    n 1 - 2 [a,b] [ n swap mod 0 &gt; ] all? ;

    MEMO: sexyprimes ( n n -- r r )
    [a,b] [ prime? ] filter [ 6 + ] map [ prime? ] filter dup [ 6 - ] map ;

    5 10 1000 * sexyprimes . .

Bash(zsh):

    #!/usr/bin/zsh
    function prime {
      for (( i = 2; i &lt; $1; i++ )); do
        if [[ $[$1%i] == 0 ]]; then
          echo 1
          exit
        fi
      done
      echo 0
    }

    function sexy-primes {
      for (( i = 9; i &lt;= $1; i++ )); do
        j=$[i-6]
        if [[ $(prime $i) == 0 &amp;&amp; $(prime $j) == 0 ]]; then
          echo $j $i
        fi
      done
    }

    sexy-primes 10000

##Questions

1. Why Scala is so fast? Is it because of **static typing**? Or it is just using JVM very efficiently?
2. &lt;s&gt;Why such a huge difference between Ruby and Python? I thought these two are not somewhat totally different. Maybe my code is wrong. Please enlighten me! Thanks.&lt;/s&gt; **UPD** Yes, that was error in my code. Python and Ruby 1.9 are pretty equal.
3. Really impressive jump in productivity between Ruby versions.
4. Can I optimize Clojure code by adding type declarations? Will it help?


  [1]: https://en.wikipedia.org/wiki/Sexy_prime

Interpreting a benchmark in C, Clojure, Python, Ruby, Scala and others

After update to Mountain Lion, I tried install 1.8.7, and I got  error. X11 file not found, I installed Xquarkz, but nothing changed. Whats wrong?

    Fail to find [tclConfig.sh, tkConfig.sh]
    Use MacOS X Frameworks.
    
    Find Tcl/Tk libraries. Make tcltklib.so which is required by Ruby/Tk.
    clang -I. -I../.. -I../../. -I../.././ext/tk -DHAVE_RB_SAFE_LEVEL -DHAVE_RB_HASH_LOOKUP -DHAVE_RB_PROC_NEW -DHAVE_RB_OBJ_TAINT -DHAVE_ST_PTR -DHAVE_ST_LEN -DRUBY_VERSION=\&quot;1.8.7\&quot; -DRUBY_RELEASE_DATE=\&quot;2012-06-29\&quot;  -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE   -DWITH_TCL_ENABLE_THREAD=0 -fno-common -g -O2  -fno-common -pipe -fno-common   -c stubs.c
    In file included from stubs.c:10:
    /usr/include/tk.h:78:11: fatal error: &#39;X11/Xlib.h&#39; file not found
    #       include &lt;X11/Xlib.h&gt;
                    ^
    1 error generated.
    make[1]: *** [stubs.o] Error 1
    make: *** [all] Error 1

Mountain Lion rvm install 1.8.7 x11 error

When including the factory_bot_rails gem in your dev and test blocks in Gemfile, rails will generate factories automatically when your models are generated. 

Is there a way to generate factories after your models have been generated?

---

Note: FactoryBot was previously named FactoryGirl

Can FactoryBot generate factories after your models have been created?

This questions stems from: https://stackoverflow.com/questions/11313872/how-to-link-form-after-creating-rails-join-table

I am creating the join table between my Product and Category Models.

What should the join table be named? categories_products or category_products or something else?

Rails naming convention for join table

I am trying to understand what `has_many :through` is and when to use it (and how). However, I am not getting it. I am reading Beginning Rails 3 and I tried Googling, but I am not able to understand. 

When to use a &quot;has_many :through&quot; relation in Rails?

Let&#39;s say I have the following classes

    class SolarSystem &lt; ActiveRecord::Base
      has_many :planets
    end

    class Planet &lt; ActiveRecord::Base
      scope :life_supporting, where(&#39;distance_from_sun &gt; ?&#39;, 5).order(&#39;diameter ASC&#39;)
    end

`Planet` has a scope `life_supporting` and `SolarSystem` `has_many :planets`. I would like to define my has_many relationship so that when I ask a `solar_system` for all associated `planets`, the `life_supporting` scope is automatically applied. Essentially, I would like `solar_system.planets == solar_system.planets.life_supporting`.

Requirements
------------

- I do **not** want to change `scope :life_supporting` in `Planet` to

  `default_scope where(&#39;distance_from_sun &gt; ?&#39;, 5).order(&#39;diameter ASC&#39;)`

- I&#39;d also like to prevent duplication by not having to add to `SolarSystem`

  `has_many :planets, :conditions =&gt; [&#39;distance_from_sun &gt; ?&#39;, 5], :order =&gt; &#39;diameter ASC&#39;`

Goal
----

I&#39;d like to  have something like

`has_many :planets, :with_scope =&gt; :life_supporting`

Edit: Work Arounds
============
As @phoet said, it may not be possible to achieve a default scope using ActiveRecord. However, I have found two potential work arounds. Both prevent duplication. The first one, while long, maintains obvious readability and transparency, and the second one is a helper type method who&#39;s output is explicit.

    class SolarSystem &lt; ActiveRecord::Base
      has_many :planets, :conditions =&gt; Planet.life_supporting.where_values,
        :order =&gt; Planet.life_supporting.order_values
    end

    class Planet &lt; ActiveRecord::Base
      scope :life_supporting, where(&#39;distance_from_sun &gt; ?&#39;, 5).order(&#39;diameter ASC&#39;)
    end

Another solution which is a lot cleaner is to simply add the following method to `SolarSystem`

    def life_supporting_planets
      planets.life_supporting
    end

and to use `solar_system.life_supporting_planets` wherever you&#39;d use `solar_system.planets`.

Neither answers the question so I just put them here as work arounds should anyone else encounter this situation.

Use a scope by default on a Rails has_many relationship

I&#39;ve been trying to figure out how Ryan Bates, in his [Facebook Authentication screencast][1],  is setting the following &quot;FACEBOOK_APP_ID&quot; and &quot;FACEBOOK_SECRET&quot; environment variables.

    provider :facebook, ENV[&#39;FACEBOOK_APP_ID&#39;], ENV[&#39;FACEBOOK_SECRET&#39;]

There are similar-ish questions around, but no answers that I&#39;ve been able to get to work on Rails 3.2.1.

**UPDATE:**

As of May 2013, my preferred way to handle ENV variables is via the [Figaro gem][2]


  [1]: http://railscasts.com/episodes/360-facebook-authentication
  [2]: https://github.com/laserlemon/figaro

Setting Environment Variables in Rails 3 (Devise + Omniauth)

I have this code: 

    &lt;%= link_to image_tag(&quot;facebook.png&quot;, :class =&gt; &quot;facebook_icon&quot;, :alt =&gt; &quot;Facebook&quot;, :target =&gt; &quot;_blank&quot;),                 
                &quot;http://www.facebook.com/mypage&quot; %&gt;

How can I make it open in a new tab when a user clicks the link?

Rails: Open link in new tab (with &#39;link_to&#39;)

I am using sidekiq in my rails application.
By Default, Sidekiq can be accessed by anybody by appending &quot;/sidekiq&quot; after the url.
I want to password protect / authenticate only the sidekiq part. How can i do that?

How can I password-protect my /sidekiq route (i.e. require authentication for the Sidekiq::Web tool)?

I&#39;m used to using delayed_jobs method of going into the console to see whats in the queue, and the ease of clearing the queue when needed.  Are there similar commands in Sidekiq for this?  Thanks!

Are there console commands to look at whats in the queue and to clear the queue in Sidekiq?

I&#39;m having a problem getting Sidekiq up and running on my Heroku deployed Rails app. I have my app working fine in development (and on Heroku without Sidekiq).

I created a Procfile with:

    worker: bundle exec sidekiq

If I run `heroku ps`, the only process I see is `web.1`. 

Should I see one for 
Sidekiq?

I do get an error:

`Redis::CannotConnectError (Error connecting to Redis on localhost:6379)` in my Heroku logs.

UPDATE: Found I probably needed `heroku addons:add redistogo`. Still not working.  I feel I&#39;m missing some basic configuration.

Is there something I need to do to get Redis up and running for my Heroku app?

I&#39;ve been using Redis/Sidekiq for about a day, so this is new to me.

Thanks!

Greg

Rails: Starting Sidekiq on Heroku

In my sidekiq dashboard, I see on the left a box with the counters 

    Processed 168
    Failed 111
    Busy 0
    Scheduled 0
    Retries 0
    Enqueued 0

How do I reset them all to 0?




How do I reset my sidekiq counters?

What possible reasons can [Sidekiq][1] prevent from processing jobs in the queue? The queue is full. The log file `sidekiq.log` indicates no activity at all. Thus the queue is full but the log is empty, and Sidekiq does not seem to process items. There seem to no worker processing jobs. Restarting Redis or flush it with [FLUSHALL][2] or [FLUSHDB][3] as no effect. Sidekiq has been started with 

&gt; bundle exec sidekiq -L log/sidekiq.log

and produces the following log file:

    2013-05-30..Booting Sidekiq 2.12.0 using redis://localhost:6379/0 with options {}
    2013-05-30..Running in ruby 1.9.3p374 (2013-01-15 revision 38858) [i686-linux]
    2013-05-30..See LICENSE and the LGPL-3.0 for licensing details.
    2013-05-30..Starting processing, hit Ctrl-C to stop

How can you find out what went wrong? Are there any hidden log files?


  [1]: https://github.com/mperham/sidekiq
  [2]: http://redis.io/commands/flushall
  [3]: http://redis.io/commands/flushdb

Content Type	Original Author	Original Content on Stackoverflow
Question	Bhushan Lodha	View Question on Stackoverflow
Solution 1 - Ruby	Sergio Tulentsev	View Answer on Stackoverflow
Solution 2 - Ruby	Gurpartap Singh	View Answer on Stackoverflow

Resque vs Sidekiq?

Ruby Problem Overview

Ruby Solutions

Solution 1 - Ruby

Resque:

Sidekiq:

Solution 2 - Ruby

Does java.util.List.isEmpty() check if the list itself is null?

Is there a way to force ASP.NET Web API to return plain text?

Attributions