Paul M. Jones

After a long delay (almost a year) Solar has a new release: version 1.0.0alpha2. You ca read more about it on Solar's new blog, which is where I'll be trying to keep all the Solar-specific stuff from now on. (You may see cross-posting between there and here from time to time.) Thanks to all who made this new release possible!

As many of you know, I maintain a series of web framework benchmarks. The project codebase is here and the most recent report is here.

It was with some interest, then, that I viewed Rasmus Lerdorf's slides on the subject of performance benchmarking. I'm beginning to think there's something unexpected or unexamined in his testing methodology.

Note: see the update at the end of this entry.

On this slide, Rasmus notes the following:

• Static HTML nets 611.78 trans/sec
• Trivial PHP nets 606.77 trans/sec

This would seem to indicate that the mere invocation of PHP, on Rasmus' setup, reduces Apache's performance from serving static pages by less than 1%.

In my testing on Amazon EC2 small instances, I note somewhat different results:

• Static HTML nets 2309.14 req/sec
• Trivial PHP nets 1320.47 req/sec

The net reduction there is about 43%. Yes, this is with opcode caching turned on.

I then became really curious as to how Rasmus might have his system set up, to see only a 1% bit of "added overhead" from PHP being invoked. It would be nice if I could set up my own systems the same way.

When I asked about that at work, my colleague Elizabeth Smith opined that maybe Rasmus' web server is running all requests through the PHP interpreter, not just PHP files. That sounded like a good intuition to me, so I set up an EC2 instance to try it out.

Per the setup instructions on this page I built an EC2 server the same as I've done for my own benchmarking reports. I didn't check out the whole project, though; this time we just need the "bench", "baseline-html", and "baseline-php" directories.

As a reminder, the baseline index.html page is just the following plain text ...

Hello World!

... and the baseline index.php page is the following single line of PHP code:

<?php echo 'Hello World!'; ?>

The php5.conf file for Apache looks like this by default ...

<IfModule mod_php5.c>
  AddType application/x-httpd-php .php .phtml .php3
  AddType application/x-httpd-php-source .phps
</IfModule>

... and we're going to leave it alone for a bit.

Using ab -c 10 -t 60 to benchmark baseline-html and baseline-php with the default php5.conf gives us these results (an average over 5 runs each):

               |      avg
-------------- | --------
baseline-html  |  2367.02
baseline-php   |  1270.15

That's a 47% drop for invoking PHP. (That is itself 4 points different than the numbers I show above, so it appears there are some variables I have not controlled for, or maybe I just need to let this run longer than 5 minutes to smooth out the deviations.)

To test our hypothesis, we modify the php5.conf file to add .html to the list of files that get passed through PHP ...

<IfModule mod_php5.c>
  AddType application/x-httpd-php .html .php .phtml .php3
  AddType application/x-httpd-php-source .phps
</IfModule>

... restart Apache, and run the same ab tests again:

framework      |      avg
-------------- | --------
baseline-html  |  1348.80
baseline-php   |  1341.31

That's less than a 1% drop -- close enough to make make me think that Rasmus might be pushing everything through the PHP interpreter, regardless of whether or not it's a PHP file.

If that is true (and it's a big "if"), then merely invoking PHP does appear to cause about a 45% drop (give or take) in Apache's responsiveness, which is contrary to the point Rasmus makes on this slide about PHP "rarely" being a bottleneck -- and I say that as someone who works with PHP almost exclusively. In fairness, I am depending only on the text of his slides here, so he may have said something to that effect in the presentation itself.

Failure modes on this analysis:

• I am using XCache and not APC for the opcode cache. (Why? Because it works with both Lighttpd+FCGI and Apache+modphp, at least the last time I checked, and I'm interested in the differences between those two setups.)

• I am using an EC2 server, which is more production-ish than Rasmus' laptop.

• I am using ab to benchmark with, not siege. I tried using Siege and did not notice any significant differences, so I'm sticking with the ab tools I've built for now.

I can't imagine those three differences would lead to the kind of disparity in performance that I'm seeing, but it's possible.

Has anyone else tried doing this?

Rasmus, if you have the time and inclination, would you care to shed some light on these prognostications?

Update: Is It EC2?

Rasmus replies below that he did not, in fact, have PHP running for all .html files.

For me, the next question was to see what the real difference on EC2 is between no cache, XCache, and APC.

No cache:

               |      avg
-------------- | --------
baseline-html  |  2339.25
baseline-php   |  1197.28

XCache (copied from above)

               |      avg
-------------- | --------
baseline-html  |  2367.02
baseline-php   |  1270.15

APC:

               |      avg
-------------- | --------
baseline-html  |  2315.83
baseline-php   |  1433.91

So on EC2, you get about 1200 req/sec without caching, about 1300 req/sec with XCache, and about 1400 req/sec with APC, in the "hello world" baseline scenarios.

Maybe this is all an artifact of how EC2 works, then? I have no idea. Next step is to test on non EC2 systems, if I can find one that others can reasonably build on themselves (since one of the goals here is for others to be able to duplicate the results).

By popular request, here is an update of my web framework benchmarks report. You can see previous result sets here:

• How Fast Is Your Framework?
• New Year's Benchmarks
• Framework and Application Benchmarking slides at DCPHP 2007

Before you comment on this post, please have the courtesy to read at least the first two articles above; I am tired of refuting the same old invalid arguments about "hello world makes no sense", "if you cache, it goes faster", "the ORM systems are different", and "speed isn't everything" with people who have no understanding of what these reports actually say.

Full disclosure: I am the lead developer on the Solar Framework for PHP 5, and I was an original contributor to the Zend framework.

In the interest of putting to rest any accusations of bias or favoritism, the entire project codebase is available for public review and criticism here.

Flattered By Imitators

They say that imitation is the sincerest form of flattery. As such, I am sincerely flattered that the following articles and authors have adopted methodologies strikingly similar to the methodology I outlined in Nov 2006.

• SellersRank here and here.
• AVNet Labs here.
• Rasmus Lerdorf here. I am considering writing a separate post about this talk by Rasmus.

Methodology, Setup, and Source Code

The methodology in this report is nearly identical to that in previous reports. I won't duplicate that narrative here; please see this page for the full methodology.

The only difference from previous reports regards the server setup. Although I'm still using an Amazon EC2 instance, I now provide the full setup instructions so you can replicate the server setup as well as the framework setup. See this page for server setup instructions.

Finally, you can see all the code used for the benchmarking here.

Results, Part 1

Update: FYI, opcode caching is turned on for these results.

The "avg" column is the number of requests/second the framework itself can deliver, with no application code, averaged over 5 one-minute runs with 10 concurrent users. That is, the framework dispatch cycle of "boostrap, front controller, page controller, action method, view" will never go any faster than this.

The "rel" column is a percentage relative to PHP itself. Thus, if you see "0.1000" that means the framework delivers 10% of the maximum requests/second that PHP itself can deliver.

We see that the Apache server can deliver 2300 static "hello world" requests/second. If you use PHP to echo "Hello World!" you get 1300 requests/second; that is the best PHP will get on this particular server setup.

Cake: After conferring with the Cake lead developers, it looks like the 1.2 release has some serious performance issues (more than 50% drop in responsiveness from the 1.1 release line). They are aware of this and are fixing the bugs for a 1.2.0-rc3 release.

Solar: The 1.0.0-alpha1 release is almost a year old, and while the unreleased Subversion code is in production use, I make it a point not to benchmark unreleased code. I might do a followup report just on Solar to show the decline in responsiveness as features have been added.

Symfony: Symfony remains the least-responsive of the tested frameworks (aside from the known-buggy Cake 1.2.0-rc1 release). No matter what they may say about Symfony being "fast at its core", it does not appear to be true, at least not in comparison to the other frameworks here. But to their credit, they are not losing performance. (Could it be there's not much left to lose? ;-) In addition, I continue to find Symfony to be the hardest to set up for these reports -- more than half my setup time was spent on Symfony alone.

Zend: The difference between the 1.0 release and the 1.5 release is quite dramatic: a 25% drop in responsiveness. And then another 10% drop between 1.5 and 1.6.

To sum up, my point from earlier posts that "every additional line of code will reduce responsiveness" is illustrated here. Each of the newer framework releases has added features, and has slowed down as a result. This is neither good nor bad in itself; it is an engineering and economic tradeoff.

Results, Part 2

I have stated before that I don't think it's fair to compare CodeIgniter and Prado to Cake, Solar, Symfony, and Zend, because they are (in my opinion) not of the same class. Prado especially is entirely unlike the others.

Even so, I keep getting requests to benchmark them, so here are the results; the testing conditions are idential to those from the main benchmarking.

CodeIgniter: Even the CI folks are not immune to the rule that "there is no such thing as a free feature"; between 1.5.4 and 1.6.2 releases they lost about 18% of their requests/second. However, they are still running at 14.5% of PHP's maximum, compared with the 11.68% of Solar-1.0.0-alpha1 (the most-responsive of the frameworks benchmarked above), so it's clearly the fastest of the bunch.

Prado: Prado works in a completely different way than the other frameworks listed here. Even though it is the slowest of the bunch, it's simply not fair to compare it in terms of requests/second. If the Prado way of working is what you need, then the requests/second comparison will be of little value to you.

This Might Be The Last Time

Although I get regular requests to update these benchmark reports, it's very time-consuming and tedious. It took five days to prepare everything, add new framework releases, make the benchmark runs, do additional research, and then write this report. As such, I don't know when (if ever) I will perform public comparative benchmarks again; my thanks to everyone who provided encouragement, appreciation, and positive feedback.

In the spirit of some other framework projects, the Solar Framework for PHP 5 now offers a ready-to-use Solar system to get new users off to a quick start. It's not prepared as a tarball just yet, but it is available for checkout or export using Subversion from http://svn.solarphp.com/system/trunk.

For example, if you make a checkout in your document root ...

$ cd /var/www/html
$ svn checkout http://svn.solarphp.com/system/trunk solar

... and follow the README instructions, you will have a fully-operational installation in very short order, including an SQLite database, authentication, and three example applications:

http://example.com/solar/index.php

A simple "hello world"

http://example.com/solar/index.php/hello-app

A complex "hello world" with authentication and localization

http://example.com/solar/index.php/bookmarks

A "bookmarks" application.

(Note that the "index.php" is only in the evaluation deployment; when you create a virtual host and point it at the Solar system document root, a .htaccess file makes the "index.php" unnecessary.)

You can read more about the structure and principles of the Solar system here.

Several developers have asked me what "BREAD" means in web applications. Most everyone knows that CRUD is "create, read, update, delete," but I think that misses an important aspect of web apps: the listing of records to select from.

I don't recall where I first heard the term BREAD; it stands for "browse, read, edit, add, delete". That covers more of what common web apps do, including the record listings. It even sounds nicer: "crud" is something icky, but "bread" is warm and fulfilling. That's why I tend to use the term BREAD instead of CRUD, especially when it comes to Solar and action-method names in the application logic.

Update 1 (2008-08-21): Wow, lot of traffic from Reddit and Y-Combinator on this one. Be sure to check out my post on Web Framework Benchmarking, and of course the Solar Framework for PHP 5.

I see a couple of comments saying that "browse is the same thing as read, it's just a special-case of read." I can see where that would be true, in a limited way. Using similar logic, one could argue that "add" is a special case of "edit", it just happens that the record isn't there yet; and then "delete" is another special case of "edit", you're just editing it out of existence. So that leaves you with just Read (one/many) and Edit (existing/non-existing/out-of-existence).

I think that takes things way too far. ;-) The special cases of "edit" are *so* special that they deserve their own logic. I think the same thing applies to "browse" -- it might be a special case of "read", but it's different-enough to deserve its own place.

Update 2: Matthew Weier O'Phinney refreshes my memory -- he mentioned the term to me years ago in a discussion about his PHP port of CGI::App. Thanks, Matthew!

Update 3: I said above that you could reduce all operations to "read" (with 2 cases) and "edit" (with 3 cases). It occurs to me now that those correspond to the way GET and POST are most-widely used. So maybe it wasn't such a silly argument after all. ;-)

Read the Reddit discussion about this post here.

As many of you know, I've been the lead of many different PHP libraries over the years: Contact_Vcard_Parse, Contact_Vcard_Build, DB_Table, Text_Wiki, and others. As each matured, I handed them over to other maintainers who continued to improve on them and take them to greater heights. Now that time has come for Savant, one of my early and favorite PHP projects.

Due to time constraints, mostly because of my Solar framework project, I haven't been able to pay as much attention to Savant as I think it deserves, so I made the hard decision to put it up for adoption. Lucky for the Savant community, Brett Bieber (aka Salty Beagle) of the PEAR Group picked up on that call right away. Brett is now the steward and lead developer of the Savant Template System for PHP.

The transfer of code, domain names, and hosting is complete, but the transition period might be a bit bumpy, so please bear with us. Brett is committed to "carrying the torch" for Savant (his words). Anyone who wants to help out the new project lead can contact him at "brett.bieber --at-- gmail --dot-- com".

Thanks, Brett, for taking over the project, and good luck!

I plan on writing a much lengthier post about The Dark Knight, and especially about Heath Ledger's portrayal of the Joker. But I want to get this bit out first.

It took me a while to figure out what it is about the Joker in this movie that strikes me as so fascinating and familiar and yet so terrifying, but I think I have it: Ledger takes the intense psychosis of Hannibal Lecter and mixes in the coyote characteristics of Daffy Duck. There's likely a lot more to it than that, but I've seen the movie three times now -- you tell me:

+

=

(The Joker was always my favorite villain, and Daffy is one of my favorite Warner Brothers characters, so maybe I'm predisposed to pick out similar behaviors.)

The folks at php.net have given me a very nice birthday present. As of today, they are end-of-lifing PHP version 4. Thanks guys, this is something I've wanted for a while now!

(Yes, I know, I've done no blogging in far too long. I've got a stack of stuff to blog about, but it's all rather heavy. In the mean time, here's something light.)

When executing code at the command line using php -r and PHP 5.2.5, be sure not to extend the Exception class. It will cause a segmentation fault.

For example, the following causes no trouble at all:

Samurai:~ pmjones$ php -r "throw new Exception();"
PHP Fatal error:  Uncaught exception 'Exception' in Command line code:1
Stack trace:
#0 {main}
  thrown in Command line code on line 1

But the next example gives a segmentation fault following a long ... pause ... after the stack trace output:

Samurai:~ pmjones$ php -r "class Foo extends Exception {} throw new Exception();"
Fatal error: Uncaught exception 'Exception' in Command line code:1
Stack trace:
#0 {main}
  thrown in Command line code on line 1
Segmentation fault

Note that we didn't even throw the extended Foo exception; we threw the native PHP exception. The mere presence of the extended class is enough to cause the segfault.

It took me two evenings to track this down; what you see here is the simplified generic case. I've entered a bug with the PHP guys here.

Update: I thought I was running 5.2.6, but I was wrong; this was occurring on PHP 5.2.5. Note to self: check to make sure you're running the latest version. :-)

Update (2008-08-12): These guys found the problem earlier, too: https://bugs.launchpad.net/ubuntu/+source/php5/+bug/198246.

Note to self: next time the bathtub won't drain, first check to make sure the plug is open **before** you assume it's clogged and pour 2 1/2 bottles of Drano down the pipe.