The State of Perl

A colleague of mine recently asked me about Perl's future. Specifically, he wondered if we have any tricks up our sleeves to compete against today's two most popular platforms: .NET and Java. Without a second's hesitation, I repeated the same answer I've used for years when people ask me if Perl has a future:

        Perl certainly is alive and well.  The Perl 6 development team is
        working very hard to define the next version of the Perl language.
        Another team of developers is working hard on Parrot, the next-
        generation runtime engine for Perl 6.  Parrot is being designed to
        support dynamic languages like Perl 6, but also Python, Ruby and
        others.  Perl 6 will also support a transparent migration of
        existing Perl 5 code.

Then I cheerfully continued with this addendum:

        Fotango is sponsoring one of their developers, Arthur Bergman, to
        work on Ponie, the reimplementation of Perl 5.10 on top of Parrot.

That is often a sufficient answer to the question, "Does Perl have a future?"

However, my colleague already knew about Perl 6 and Parrot. Perl 6 was announced with a great deal of fanfare about three and a half years ago. The Parrot project, announced as an April Fool's joke in 2001, is now over two years old as a real open source project. While Parrot has made some amazing progress, it is not yet ready for production usage, and will not be for some time to come. The big near-term goal for Parrot is to execute Python bytecode faster than the standard CPython implementation, and to do so by the Open Source Convention in July 2004. There's a fair amount of work to do between now and then, and even more work necessary to take Parrot from that milestone to something you can use as a replacement for something like, say, Perl.

So, aside from the grand plans of Perl 6 and Parrot, does Perl really have a future?

The State of Perl Development

Perl 6 and Parrot do not represent our future, but rather our long-term insurance policy. When Perl 6 was announced, the Perl 5 implementation was already about seven years old. Core developers were leaving perl5-porters and not being replaced. (We didn't know it at the time, but this turned out to be a temporary lull. Thankfully.) The source code is quite complex, and very daunting to new developers. It was and remains unclear whether Perl can sustain itself as an open source project for another ten or twenty years if virtually no one can hack on the core interpreter.

In 2000, Larry Wall saw Perl 6 as a means to keep Perl relevant, and to keep the ideas flowing within the Perl world. The fear at the time was quite palpable: if enough alpha hackers develop in Java or Python and not Perl, the skills we have spent years acquiring and honing will soon become useless and literally worthless. Furthermore, backwards compatibility with thirteen years (now sixteen years) of working Perl code was starting to limit the ease with which Perl can adapt to new demands. Taken to a logical extreme, all of these factors could work against Perl, rendering it yesterday's language, incapable of effectively solving tomorrow's problems.

The plan for Perl 6 was to provide not only a new implementation of the language, but also a new language design that could be extended by mere mortals. This could increase the number of people who would be both capable and interested in maintaining and extending Perl, both as a language and as a compiler/interpreter. A fresh start would help Perl developers take Perl into bold new directions that were simply not practical with the then-current Perl 5 implementation.

Today, over three years later, the Perl development community is quite active writing innovative software that solves the problems real people and businesses face today. However, the innovation and inspiration is not entirely where we thought it would be. Instead of seeing the new language and implementation driving a new wave of creativity, we are seeing innovation in the libraries and modules available on CPAN -- code you can use right now with Perl 5, a language we all know and love.

In a very real sense, the Perl 6 project has already achieved its true goals: to keep Perl relevant and interesting, and to keep the creativity flowing within the Perl community.

What does this mean for Perl's future? First of all, Perl 5 development continues alongside Perl 6 and Parrot. There are currently five active development branches for Perl 5. The main branch, Perl 5.8.x, is alive and well. Jarkko Hietaniemi released Perl 5.8.1 earlier this year as a maintenance upgrade to Perl 5.8.0, and turned over the patch pumpkin to Nick Clark, who is presently working on building Perl 5.8.3. In October, Hugo van der Sanden released the initial snapshot of Perl 5.9.0, the development branch that will lead to Perl 5.10. And this summer, Fotango announced that Arthur Bergman is working on Ponie, a port of Perl 5.10 to run on top of Parrot, instead of the current Perl 5 engine. Perl 5.12 may be the first production release to run on top of the new implementation.

For developers who are using older versions of Perl for compatibility reasons, Rafael Garcia-Suarez is working on Perl 5.6.2, an update to Perl 5.6.1 that adds support for recent operating-system and compiler releases. Leon Brocard is working on making the same kinds of updates for Perl 5.005_04.

Where is Perl going? Perl is moving forward, and in a number of parallel directions. For workaday developers, three releases of Perl will help you get your job done: 5.8.x, 5.6.x and, when absolutely necessary, 5.005_0x. For the perl5-porters who develop Perl itself, fixes are being accepted in 5.8.x and 5.9.x. For bleeding-edge developers, there's plenty of work to do on with Parrot. For the truly bleeding edge, Larry and his lieutenants are hashing out the finer points of the design of the Perl 6 language.

That describes where development of Perl as a language and as a platform is going. But the truly interesting things about Perl aren't language issues, but how Perl is used.

The State of Perl Usage

One way to get a glimpse how Perl is used in the wild is to look at CPAN. I recently took a look at the modules list (www.cpan.org/modules/01modules.index.html) and counted module distributions by the year of their most recent release. These statistics are not perfect, but they do give a reasonable first approximation of the age of CPAN distributions currently available.

        1995:   30 ( 0.51%)
        1996:   35 ( 0.59%)
        1997:   68 ( 1.16%)
        1998:  189 ( 3.21%)
        1999:  287 ( 4.88%)
        2000:  387 ( 6.58%)
        2001:  708 (12.03%)
        2002: 1268 (21.55%)
        2003: 2907 (49.40%)
        cpan: 5885 (100.00%)

Interestingly, about half of the distributions on CPAN were created or updated in 2003. A little further analysis shows that nearly 85% of these distributions were created or updated since the Perl 6 announcement in July 2000. Clearly, interest in developing in Perl is not on the wane. If anything, Perl development, as measured by CPAN activity, is quite healthy.

Looking at the "freshness" of CPAN doesn't tell the whole story about Perl. It merely indicates that Perl developers are actively releasing code on CPAN. Many of these uploads are new and interesting modules, or updates that add new features or fix bugs in modules that we use every day. Some modules are quite stable and very useful, even though they have not been updated in years. But many modules are old, outdated, joke modules, or abandoned.

A pessimist looks at CPAN and sees abandoned distributions, buggy software, joke modules and packages in the early stage of development (certainly not ready for "prime time" use). An optimist looks at CPAN and sees some amazingly useful modules (DBI, LWP, Apache::*, and so on), and ignores the less useful modules lurking in the far corners of CPAN.

Which view is correct? Looking over the module list, only a very small number of modules are jokes registered in the Acme namespace: about 85 of over 5800 distributions, or less than 2% of the modules on CPAN. Of course, there are joke modules that are not in the Acme namespace, like Lingua::Perligata::Romana and Lingua::Atinlay::Igpay. Yet the number of jokes released as CPAN modules remains quite small when compared to CPAN as a whole.

But how much of CPAN is actually useful? It depends on what kind of problems you're solving. Let's assume that only the code released within the last three years, or roughly 82% of CPAN, is worth investigating. Let's further assume that everything in the Acme namespace can be safely ignored, and that the total number of joke modules is no more than twice the number of Acme modules. Ignoring a further 3-4% of CPAN leaves us with about 78%, or over 4,000 distributions, to examine.

How much of this code is production-quality? It's quite difficult to say, actually. These modules cover a stunningly diverse range of problem domains, including, but not limited to:

  • Application servers
  • Artificial intelligence algorithms
  • Astronomy
  • Audio
  • Bioinformatics
  • Compression and encryption
  • Content management systems (for both small and large scale web sites)
  • Database interfaces
  • Date/Time Processing
  • eCommerce
  • Email processing
  • GUI development
  • Generic algorithms from computer science
  • Graphing and charting
  • Image processing
  • Mathematical and statistical programming
  • Natural language processing (in English, Chinese, Japanese, and Finnish, among others)
  • Network programming
  • Operating-system integration with Windows, Solaris, Linux, Mac OS, etc.
  • Perl development support
  • Perl/Apache integration
  • Spam identification
  • Software testing
  • Templating systems
  • Text processing
  • Web services, web clients, and web servers
  • XML/HTML processing

...and that's a very incomplete sample of the kinds of distributions available on CPAN today. Suffice it to say that hundreds, if not thousands, of CPAN modules are actively used on a daily basis to solve the kinds problems that we regularly face.

And isn't that the real definition of production quality, anyway?

The Other State of Perl Usage

As Larry mentioned in his second keynote address to the Perl Conference in 1998 (www.perl.com/pub/a/1998/08/show/onion.html), the Perl community is like an onion. The important part isn't the small core, but rather the larger outer layers where most of the mass and all of the growth are found. Therefore, the true state of Perl isn't about interpreter development or CPAN growth, but in how we all use Perl every day.

Why do we use Perl every day? Because Perl scales to solve both small and large problems. Unlike languages like C, C++, and Java, Perl allows us to write small, trivial programs quickly and easily, without sacrificing the ability to build large applications and systems. The skills and tools we use on large projects are also available when we write small programs.

Programming in the Small

Here's a common example. Suppose I want to look at the O'Reilly Perl resource page and find all links off of that page. My program starts out by loading two modules, LWP::Simple to fetch the page, and HTML::LinkExtor to extract all of the links:

        #!/usr/bin/perl -w

        use strict;
        use LWP::Simple;
        use HTML::LinkExtor;

        my $ext = new HTML::LinkExtor;
        $ext->parse(get("http://perl.oreilly.com/"));
        my @links = $ext->links();

At this point, I have the beginnings of a web spider or possibly a screen scraper. With a few regular expressions and a couple of list operations like grep, map, or foreach, I can whittle this list of links down to a list of links to Safari, the O'Reilly's book catalog, or new articles on Perl.com. A couple of lines more, and I could store these links in a database (using DBI, DB_File, GDBM, or some other persistent store).

I've written (and thrown away) many programs like this over the years. They are consistently easy to write, and typically less than one page of code. That says a lot about the capabilities Perl and CPAN provide. It also says a lot about how much a single programmer can accomplish in a few minutes with a small amount of effort.

Yet the most important lesson is this: Perl allows us to use the same tools we use to write applications and large systems to write small scripts and little hacks. Not only are we able to solve mundane problems quickly and easily, but we can use one set of tools and one set of skills to solve a wide range of problems. Furthermore, because we use the same tools, our quick hacks can work alongside larger systems.

Programming in the Large

Of course, it's one thing to assert that Perl programs can scale up beyond the quick hack. It's another thing to actually build large systems with Perl. The Perl Success Stories Archive (perl.oreilly.com/news/success_stories.html) details many such efforts, including many large systems, high-volume systems, and critical applications.

Then there are the high-profile systems that get a lot of attention at Perl conferences and on various Perl-related mailing lists. For example, Amazon.com, the Internet's largest retailer, uses HTML::Mason for portions of their web site. Another fifty-odd Mason sites are profiled (www.masonhq.com/about/sites.html) at www.masonhq.org, including Salon.com, AvantGo, and DynDNS.

Morgan Stanley is another big user of Perl. As far back as 2001, W. Phillip Moore talked about where Perl and Linux fit into the technology infrastructure at Morgan Stanley. More recently, Merijn Broeren detailed (conferences.oreillynet.com/cs/os2003/view/e_sess/4293) how Morgan Stanley relies on Perl to keep 9,000 of its computers up and running non-stop, and how Perl is used for a wide variety of applications used worldwide.

ValueClick, a provider of high-performance Internet advertising, pushes Perl in a different direction. Each day, ValueClick serves up over 100 million targeted banner ads on publisher web sites. The process of choosing which ad to send where is very precise, and handled by some sophisticated Perl code. Analyzing how effective these ads are requires munging through huge amounts of logging data. Unsurprisingly, ValueClick uses Perl here, too.

Ticketmaster sells tickets to sporting and entertainment events in at least twenty countries around the world. In a year, Ticketmaster sells over 80 million tickets worldwide. Recently, Ticketmaster sold one million tickets in a single day, and about half of those tickets were sold over the Web. And the Ticketmaster web site is almost entirely written in Perl.

These are only some of the companies that use Perl for large, important products. Ask around and you'll hear many, many more stories like these. Over the years, I've worked with more than a few companies who created some web-based product or service that was built entirely with Perl. Some of these products were responsible for bringing in tens of millions of dollars in annual revenue.

Clearly, Perl is for more than just simple hacks.

The New State of Perl Usage

Many companies use Perl to build proprietary products and Internet-based services they can sell to their customers. Still more companies use Perl to keep internal systems running, and save money through automating mundane processes.

A new way people are using Perl today is the open source business. Companies like Best Practical and Kineticode are building products with Perl, and earning money from training, support contracts, and custom development. Their products are open source, freely available, and easy to extend. Yet there is enough demand for add-on services that these companies are profitable and sustain development of these open source products.

Best Practical Solutions (www.bestpractical.com) develops Request Tracker, more commonly known as RT (www.bestpractical.com/rt). RT is an issue-tracking system that allows teams to coordinate their activities to manage user requests, fix bugs, and track actions taken on each task. As an open source project, RT has been under development since 1996, and has thousands of corporate users, including those listed on the testimonials page (www.bestpractical.com/rt/praise.html). Today, RT powers bug tracking for Perl development (rt.perl.org/perlbug), and for CPAN module development (rt.cpan.org). Many organizations rely on the information they keep in RT, sometimes upwards of 1000 issues per day, or 300,000 issues that must be tracked and resolved each year.

Kineticode (www.kineticode.com)is another successful open source business built around a Perl product, the Bricolage content management system (www.bricolage.cc). Bricolage is used by some rather large web sites, including ETOnline (www.etonline.com) and the World Health Organization (www.who.int). Recently, the Howard Dean campaign (www.deanforamerica.com) adopted Bricolage as its content management system to handle the site's frequent updates in the presence of millions of pageviews per day, with peak demand more than ten times that rate.

A somewhat related business is SixApart (www.sixapart.com), makers of the ever-popular MovableType (www.movabletype.org). SixApart offers MovableType with a free license for personal and non-commercial use, but charges a licensing fee for corporate and commercial use. Make no mistake, MovableType is proprietary software, even though it is implemented in Perl. Nevertheless, SixApart has managed to build a profitable business around their Perl-based product.

Surely these are the early days for businesses selling or supporting software written in Perl. These three companies are not the only ones forging this path, although they are certainly three of the most visible.

Conclusion

I started looking into the state of Perl today when my colleague asked me if Perl has a future. He challenged me to look past my knee-jerk answers, "Of course Perl has a future!" and "Perl's future is in Perl 6 and Parrot!" I'm glad he did.

There's a lot of activity in the Perl world today, and much of it quite easily overlooked. Core development is moving along at a respectable pace; CPAN activity is quite healthy; and Perl remains a capable environment for solving problems, whether they need a quick hack, a large system, or a Perl-based product. Even if we don't see Perl 6 in 2004, there's a lot of work to be done in Perl 5, and a lot of work Perl 5 is still quite capable of doing.

Then there's the original question that started this investigation rolling: "Can Perl compete with Java and .NET?" Clearly, when it comes to solving problems, Perl is at least as capable a tool as Java and .NET today. When it comes to evangelizing one platform to the exclusion of all others, then perhaps Perl can't compete with .NET or Java. Then again, when did evangelism ever solve a problem that involved sitting down and writing code?

Of course, if Java or .NET is more your speed, by all means use those environments. Perl's success is not predicated on some other language's failure. Perl's success hinges upon helping you get your job done.

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