# Raindrops - real-time stats for preforking Rack servers

**URL:** <https://www.ruby-forum.com/t/raindrops-real-time-stats-for-preforking-rack-servers/186504>\
**Category:** Ruby\
**Created:** [April 8, 2010, 3:11am UTC](https://www.ruby-forum.com/t/raindrops-real-time-stats-for-preforking-rack-servers/186504 "2010-04-08T03:11:00Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![ericw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/97f17d/32.png) [@ericw](https://www.ruby-forum.com/u/ericw)\
**Post date:** [April 8, 2010, 3:11am UTC](https://www.ruby-forum.com/t/raindrops-real-time-stats-for-preforking-rack-servers/186504/1 "2010-04-08T03:11:00Z")

</div>

Raindrops is a real time stats package to show statistics for Rack HTTP  
servers. It is designed for preforking servers such as Rainbows! and  
Unicorn, but should support any Rack HTTP server under Ruby 1.9, 1.8 and  
possibly Rubinius (untested) on platforms supporting POSIX shared memory  
and compiled with GCC (for atomic builtins).

Raindrops includes a Struct-like Raindrops::Struct class that may be  
used  
standalone to create atomic counters shared across any number of forked  
processes under SMP.

- [http://raindrops.bogomips.org/](http://raindrops.bogomips.org/)
- removed\_email\_address@domain.invalid
- git://git.bogomips.org/raindrops.git

== Features

- counters are shared across all forked children and lock-free

- counters are kept on separate cache lines to reduce contention under  
SMP

- may expose server statistics as a Rack Middleware endpoint  
(default: “/\_raindrops”)

- middleware displays the number of actively processing and writing  
clients from a single request regardless of which worker process  
it hits.

== Linux-only Extra Features!

- Middleware response includes extra stats for bound TCP and  
Unix domain sockets (configurable, it can include stats from  
other TCP or UNIX domain socket servers).

- TCP socket stats use efficient inet\_diag facilities via netlink  
instead of parsing /proc/net/tcp to minimize overhead.  
This was fun to discover and write.

== Install

raindrops requires GCC 4.x (or compatible) or later to support the  
atomic builtins (\__sync_{add,sub}\_and\_fetch()). Atomic operations on  
other compilers may be supported if there is demand.

If you’re using a packaged Ruby distribution, make sure you have a C  
compiler and the matching Ruby development libraries and headers.

If you use RubyGems:

```
gem install raindrops

```

Otherwise grab the latest tarball from:

[http://raindrops.bogomips.org/files/](http://raindrops.bogomips.org/files/)

Unpack it, and run “ruby setup.rb”

== Usage (Rainbows!/Unicorn preload\_app=false)

If you’re using preload\_app=false (the default) in your  
Rainbows!/Unicorn  
config file, you’ll need to create the global Stats object before  
forking.

```
    require 'raindrops'
    $stats ||= Raindrops::Middleware::Stats.new

```

In your Rack [config.ru](http://config.ru):

```
    use Raindrops::Middleware, :stats => $stats

```

== Usage (Rainbows!/Unicorn preload\_app=true)

If you’re using preload\_app=true in your Rainbows!/Unicorn  
config file, just add the middleware to your stack:

In your Rack [config.ru](http://config.ru):

```
    use Raindrops::Middleware

```

== Usage (Linux-extras)

To get bound listener statistics under Linux, you need to specify the  
listener names for your server. You can even include listen sockets for  
_other_ servers on the same machine. This can be handy for monitoring  
your nginx proxy as well.

In your Rack [config.ru](http://config.ru), just pass the :listeners argument as an array of  
strings (along with any other arguments). You can specify any  
combination of TCP or Unix domain socket names:

```
    use Raindrops::Middleware, :listeners => %w(0.0.0.0:80 

```

/tmp/.sock)

See the tests/ and examples/ directory for more examples

== Development

You can get the latest source via git from the following locations:

git://git.bogomips.org/raindrops.git  
git://repo.or.cz/raindrops.git (mirror)

You may browse the code from the web and download the latest snapshot  
tarballs here:

- [real-time stats for preforking Rack servers](http://git.bogomips.org/cgit/raindrops.git) (cgit)
- [Public Git Hosting - raindrops.git/summary](http://repo.or.cz/w/raindrops.git) (gitweb)

Inline patches (from “git format-patch”) to the mailing list are  
preferred because they allow code review and comments in the reply to  
the patch.

We will adhere to mostly the same conventions for patch submissions as  
git itself. See the Documentation/SubmittingPatches document  
distributed with git on on patch submission guidelines to follow. Just  
don’t email the git mailing list or maintainer with raindrops patches.

== Contact

All feedback (bug reports, user/development discussion, patches, pull  
requests) go to the mailing list: [mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)