ANN: acme-http

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Jeremy Shaw

Apr 1, 2012, 1:46:20 PM4/1/12
to HAppS, web-devel, haskell-cafe

As we all know, the true measure of performance for a web server is
the classic PONG test. And, so the Happstack team is pleased to
announce the release of the new acme-http server!



When testing on my laptop with +RTS -N4 using the classic PONG test:

$ httperf --hog -v --server --port 8000 --uri /
--num-conns=1000 --num-calls=1000 --burst-length=20 --rate=1000

acme-http delivered 221,693.0 req/s, making it the fastest Haskell
web server on the planet.

By comparison, warp delivered 51,346.6 req/s on this machine.

The secret to acme-http's success is that it large avoids doing
anything not required to win the PONG benchmark. It does not support
timeouts, it does not check quotas, it assumes the client is HTTP 1.1,
it does not catch exceptions, and it responds to every single request
with PONG.

The goal of acme-http is two fold:

1. determine the upper-bound on Haskell web-server performance
2. push that upper bound even higher

In regards to #1, we have now established the current upper limit at
221,693.0 req/s.

In regards to #2, I believe acme-http will be useful as a place to
investigate performance bottlenecks. It is very small, only 250 lines
of code or so. And many of those lines deal with pretty-printing, and
other non-performance related tasks. Additionally, it works in the
plain IO monad. It does not use conduits, enumerators, pipes, or even
lazy IO. As, a result, it should be very easy to understand, profile,
and benchmark.

In providing such a simple environment and avoiding as much extra work
as possible we should be able to more easily answer questions like
"Why is so much RAM required?", "What is limiting the number of
connections per second", etc.

As we address these issues in acme-http, we can hopefully bring
solutions back to practical frameworks, or to the underlying GHC
implementation itself.

If performance tuning is your thing, I invite you to check out
acme-http and see if you can raise the limit even higher!

- jeremy

Michael Snoyman

Apr 1, 2012, 1:48:30 PM4/1/12
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That's awesome! I think you should pair this up with the /dev/null
datastore and then you'll be truly webscale!


Jeremy Shaw

Apr 1, 2012, 1:59:06 PM4/1/12
to, web-devel, haskell-cafe
On Sun, Apr 1, 2012 at 12:48 PM, Michael Snoyman <> wrote:

> That's awesome! I think you should pair this up with the /dev/null
> datastore and then you'll be truly webscale!

Well, acid-state does have a backend that skips writing any
transaction logs to disk making it pure memory based:

So, that is a bit like a /dev/null data store. It works really great
as long as your app never restarts :)

- jeremy

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