Traffic Server

Why Traffic Server defaults to not allow forward proxying

We have discussed numerous times on the Apache mailing lists about the reasons why Apache Traffic Server ships with a default configuration that is almost entirely locked down. Our argument has been that we want to assure that someone testing TS is not accidentally setup in the wild as an open proxy.

I recently moved all of to be served via a TS reverse proxy setup. Within minutes from setting it up, and while watching the log files, I found entries like these in the logs:

1273927263.211 0 ERR_CONNECT_FAIL/404 485 GET - NONE/- tex -
1274057848.081 0 ERR_CONNECT_FAIL/404 485 GET - NONE/- tex -
1274236765.403 4 ERR_CONNECT_FAIL/404 485 GET - NONE/- tex -

Of course, my server doesn't allow this, since it's setup to only accelerate traffic. But case in point is, I think we've done the right thing of shipping Apache Traffic Server with a very restrictive configuration.


Ogre is now running on Apache Traffic Server

I've just switched over to serve all of out of Apache Traffic Server. The site is still managed and created using Apache HTTPD, PHP and Drupal, but that is running as an "origin" server to ATS. This gives me a few benefits over serving straight out of Apache HTTPD:

  • Static content is automatically "cached" on the ATS server, and it can serve such content very fast with low latency.
  • I can jack up keep-alive much higher than I dared doing with HTTPD. Fwiw, I still use the pre-fork MPM, so I have limited number of processes and can't afford to tie those up with idle KA connections.
  • In a pinch, I could turn the HTML generated from Drupal to be cacheable, and serve straight out of ATS. I'm contemplating making this setting automatic, so when the load on the box hits a certain level, all HTML will also be cached by ATS. That would increase my capacity by at least a magnitude I think.

This change required no changes on my Drupal site, but I did change the port on my Apache HTTPD virtual host:



I then installed Apache Traffic Server to listen on port 80, and I also told it to only bind a specific IP on my server (I have three IPs for different things). I also increased the RAM cache size and Keep-Alive timeouts, so I now have these changes in etc/trafficserver/records.config:

CONFIG proxy.config.proxy_name STRING
CONFIG proxy.config.http.server_port INT 80
CONFIG proxy.config.http.keep_alive_no_activity_timeout_in INT 60
CONFIG proxy.config.http.keep_alive_no_activity_timeout_out INT 1
CONFIG proxy.config.http.transaction_no_activity_timeout_in INT 15
CONFIG proxy.config.http.transaction_no_activity_timeout_out INT 30
CONFIG proxy.config.cache.ram_cache.size LLONG 33554432

LOCAL proxy.local.incoming_ip_to_bind STRING

Next, I added a disk cache to use for ATS, etc/trafficserver/storage.config:

/disk/tmp 134217728

This creates a 128MB cache in /disk/tmp. I know, very small, but this is still experimental. Finally, I added a remapping rule to etc/trafficserver/remap.config:


After starting everything up, the entire site is now reverse proxied (or accelerated) through Apache Traffic Server! As you can see, the changes necessary to ATS are fairly small, and pretty straight forward, most of the default settings 'just work'. It's a miracle.


First "alpha" release of Apache Traffic Server

We've finally produced our first "alpha" release of Apache Traffic Server. It can be fetched from your local Apache Download Mirror. This first version, v2.0.0-alpha, should be reasonably stable as it does not contain a ton of improvements over the old Yahoo code. The 2.0.0 releases also only supports Linux, but a number of 32-bit and 64-bit distros have been tested.

We're hoping to get some testing done on this release in the next week or two, so we can make the "final" 2.0.0 release. After that, the plan is to aggressively start making "developer" releases of trunk, which has some impressive improvements (like, up to 2x the performance in some cases). Apache Traffic Server is adopting the same versioning scheme as Apache HTTPD, so, v2.0.x is a "stable" release, while v2.1.x is a developer release. This implies, of course, that the next stable release will be v2.2.0, and we're hoping to get that out the door sometime this summer!

People interested in Apache Traffic Server are highly encouraged to join our mailing lists (see the incubator page), or come join us on #traffic-server on


Traffic Server performance

I just got a new shiny desktop at home, a Quad Core i7 920, running 64-bit Linux 2.6.32 (stock Fedora Core 12). Nothing fancy, it's a $250 CPU, but I did some artificial tests of Traffic Server on it just to see where we are on a modern machine and kernel. The tests are done between two Linux boxes, both on GigE network, and with two Linksys switches in between the two boxes. So, this is definitely not a production quality network in any way. I ran with keep-alive enabled, doing 100 requests per connection, each request fetches a 500 byte body out of cache (i.e. 100% cache hit ratio). I know, this is a completely unrealistic test, but it is still interesting to see what we can do. Here's the best run out of three:

2270442 fetches on 23464 conns, 2000 max parallell, 1.13522e+09 bytes in 30 seconds
500 mean bytes/fetch
75681.40 fetches/sec, 3.78406e+07 bytes/sec
msecs/connect: 0.3878585 mean, 11.1295 max, 0.089 min
msecs/first-response: 16.3695 mean, 459.379 max, 0.1295 min

So, over 75,000 requests per second, at 16ms latency, and I think some of that latency can be attributed to the two switches (wish I had a better setup). An interesting side note, the Traffic Server process can actually use about 470% CPU on this Quad Core box, so an extra 70% of a CPU is "gained" here from Hyper Threading. How does this compare to my old desktop? Well, the old system was a Core2, and in the same test, it was able to pull off around 35k QPS.

Anyways, these results aren't too shabby, and we've just started!

Caveat: This is using the "trunk" version of Traffic Server, the first release that is soon coming out won't be quite this fast.

Update: I updated the numbers with the results after forcing my CPU to run at highest CPU frequency at all time. No overclocking though, this is a standard i7 920 setup.



Traffic Server week 1

Traffic Server has been out for a full week now. And it's been great, the interest is huge (almost overwhelming), and surprsingly, lots of people want to participate and contribute. So far, we've already achieved:

  • 64-bit port on Linux!
  • Port to Solaris (and OpenSolaris I believe)
  • Port to Ubuntu (it required a lot of changes due to glibc changes)
  • MacOSX port is partially done.

Not bad for week. If you are interested, check out our Wiki:


TS in the media

Traffic Server is finally here

Finally! We pushed the Traffic Server code to Apache SVN today! This is definitely a momentous occasion, this has been in the works for ages, and it took a lot of work and patience to happen. You wonder, why did we bother? Well, you are right, there's plenty of proxy server alternatives out there, Squid, Varnish, NginX and so on. But, we think we have a platform we can build something on that will be better than anything out there (that is free at least). Why? Well, we have

  • A scalable threaded + asynchronous state machine model. On a typical setup, 2 or 3 threads per core is enough to drive a large amount of traffic.
  • Feature-rich HTTP/1.0 and HTTP/1.1 support. We fair well in various tests like CoAdvisor.
  • Plugin architecture, making it easy (well, easier) to extend and customize your server.
  • Well documented.

I'm not saying it's perfect (far from it), but the hope is that Open Sourcing this will attract an active developer and user community around the software. So, you want more information? Well, besides visiting us on #traffic-server on, here's a bunch of links with some useful information:

Please join the mailing lists (see the Incubator page), talk to us on IRC, or just take a look at the code.

Update: Mark Nottingham (on our team now!) has a blog post with some interesting history and thoughts on TS.


OpenSourcing Traffic Server

It's been long in the making, Chuck and I have worked hard to get this through all the hurdles and red-tape. But finally, we have submitted this draft to the Apache Incubator:

We'll be making an official "announcement" soon on the Y! Developer Network, but this is pretty exciting for us.



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