To a seasoned hobbyist programmer like myself, the only truly bad news about Erlang is that it is slow. In the language of complexity analysis, Erlang programs tend to have a large constant out front but excellent asymptotic properties. For the programmer who wishes to write fast programs using Erlang — the sorts of programs that start, run, write some output, and exit — there is hope on several fronts.
A native-code compiler is available, and according to numerical benchmarks , it makes Erlang programs faster than Ruby, Perl, and PHP, albeit slower than Java and JavaScript. There is talk of a just-in-time native-code compiler, which might provide further improvements to execution time by gleaning information from the code execution itself and making appropriate optimizations. Finally, brave souls can write computationally intensive code in C via a NIF , with the important caveats that C code will block the Erlang scheduler potentially negating Erlang's concurrency capabilities , and that parallel C code is famously difficult to write.
My own choice for writing fast programs in Erlang is an alternative technology which affords all the benefits of C code without compromising the integrity of the Erlang run-time. In fact, OpenCL programs are usually faster than C programs, as OpenCL programs can take advantage of a processor's vector capabilities in a way that normally requires hand-tuned assembler code.
OpenCL programs can be compiled and executed directly from Erlang code ; in my view, it is a perfect technology for performing computationally intensive tasks that is, running those inner loops inside of a larger Erlang program. As I said, speed has not been a problem in the Erlang programs I've written. I do have some first-hand experience with OpenCL and have been quite pleased.
I wrote a map projection library in OpenCL which is about 5 times faster than the state-of-the-art Proj. I also wrote an OpenCL library for doing multivariate statistics; I haven't benchmarked it against existing libraries, but I suspect it is faster by a similar margin.
There are some peculiarities in writing OpenCL code, but it is my hope that one day all the world's tight loops will be rewritten in OpenCL and invoked from large programs written in Erlang. My desktop statistics software Wizard can help you analyze more data in less time and communicate discoveries visually without spending days struggling with pointless command syntax.
Check it out! Why I Program In Erlang By Evan Miller October 20, Translations: Urdu Erlang is a twenty-five-year-old programming language that has yet to win a popularity contest, and almost certainly will never win any medals for speed, let alone any tiaras for syntactic beauty.
What makes Erlang the best choice for your project? It depends on what you are looking to build. If you are looking into writing a number-crunching application, a graphics-intensive system, or client software running on a mobile handset, then sorry, you bought the wrong book. But if your target system is a high-level, concurrent, robust, soft real-time system that will scale in line with demand, make full use of multicore processors, and integrate with components written in other languages, Erlang should be your choice.
If somebody came to me and wanted to pay me a lot of money to build a large scale message handling system that really had to be up all the time, could never afford to go down for years at a time, I would unhesitatingly choose Erlang to build it in.
Facebook uses Erlang to power the backend of its chat service, handling more than million active users. Motorola is using Erlang in call processing products in the public-safety industry. The most popular open source Erlang applications include the following:. The 3D subdivision modeler Wings 3D, used to model and texture polygon meshes.
It is used to power services such as MochiBot and MochiAds, which serve dynamically generated content to millions of viewers daily. AMQP is an emerging standard for high-performance enterprise messaging. Although Uppsala University has for many years led the way with research on Erlang through the High Performance Erlang Project HiPE , many other universities around the world are not far behind.
With these companies, open source projects, and universities, we have just scratched the surface of what has today become a vibrant international community spread across six continents.
Blogs, user groups, mailing lists, and dedicated sites are now helping to take the community to its next level. Their conclusion was that although many of the languages had interesting and relevant features, no single language encompassed them all. As a result, they decided to invent their own. Erlang was influenced by functional languages such as ML and Miranda, concurrent languages such as ADA, Modula, and Chill, as well as the Prolog logic programming language.
With a Prolog-based Erlang virtual machine VM , the lab spent four years prototyping telecom applications with an evolving language that through trial and error became the Erlang we know today. In , Mike Williams wrote the first C-based virtual machine, and a year later, the first commercial project with a small team of developers was launched.
The project was a mobility server, allowing DECT cordless phone users to roam across private office networks. The product was successfully launched in , providing valuable feedback on improvements and missing features that got integrated into the Erlang release. In conjunction with these projects, the OTP framework was developed and released in OTP provides a framework to structure Erlang systems, offering robustness and fault tolerance together with a set of tools and libraries.
The history of Erlang is important in understanding its philosophy. The fact that web services, retail and commercial banking, computer telephony, messaging systems, and enterprise integration, to mention but a few, happen to share the same requirements as telecom systems explains why Erlang is gaining headway in these sectors.
This was done with no budget or press releases, nor with the help of the corporate marketing department. In January , the erlang. Ten years later, this number had risen to 2. This rise is a reflection of an ever-growing community resulting from a combination of successful commercial, research, and open source projects, viral marketing, blogging, and books, all driven by the need to solve hard software problems in the domain for which Erlang had originally been created.
Although Erlang on its own is an attractive programming language, its real strength becomes apparent when you put it together with the virtual machine VM and the OTP middleware and libraries. Each of them contributes to making software development in Erlang special. So, what are the features of Erlang that differentiate it from many of its peers? Erlang is a declarative language. Declarative languages work on the principle of trying to describe what should be computed, rather than saying how this value is calculated.
A function definition—particularly one that uses pattern matching to select among different cases, and to extract components from complex data structures—will read like a set of equations:.
This definition takes a shape—here a square or a circle—and depending on which kind of shape it receives, it matches the correct function clause and returns the corresponding area. In Erlang, you can pattern-match not only on high-level data but also on bit sequences , allowing a startlingly high-level description of protocol manipulation functions.
Here is the start of a function to decode TCP segments:. In the preceding code, each numeric length, such as 4 in DataOffset:4 , gives the number of bits to be matched to that variable.
By comparison, think of how you would achieve the same effect in C or Java. Another aspect of Erlang is that functions or closures are first-class data. They can be bound to a variable and can be treated just like any other data item: stored in a list, returned by a function, or communicated between processes. List comprehensions , also taken from the functional programming paradigm, combine list generators and filters, returning a list containing the elements of the list generators after the filters have been applied.
The following example of list comprehensions, which we explain fully in Chapter 9 , is an implementation of the quicksort algorithm in a couple of lines of code:.
Concurrency in Erlang is fundamental to its success. Rather than providing threads that share memory, each Erlang process executes in its own memory space and owns its own heap and stack. Processes communicate with each other via message passing , where the message can be any Erlang data value at all. This will result in a constant execution time for all requests, unlike the Java Virtual Machine, where garbage collecting affects all requests going through the system at that particular point in time or NodeJS, where a request will execute until completion, blocking other requests on that thread until it is done.
The RubyVM has not had decades of engineering resources put into it, and as a result, will not scale. There are no other Virtual Machines around with the properties of the BEAM, making it unique in its capability to predictably handle massively concurrent spikes of traffic.
It is not the fastest VM, but it is the most stable and predictable one. How do the advantages of using the BEAM apply in practice? This equates to a predictable user-experience, where a million users can be served on a single instance. All the programmer has to worry about is developing code to handle a single user a process , and the VM will automatically scale it to millions.
And if a request fails because of corrupt data or a bug in the software, all other requests will continue executing independently of it, isolating the failure. This, in turn, greatly reduced their infrastructure costs and the size of the team needed to maintain it. Similar numbers were achieved using Elixir and the Phoenix framework in From messaging, vertical scalability on a single node we move to the web.
Bleacher Report , a news app and website focusing on sports, had a similar impact on operational and infrastructure costs when changing Virtual Machine. When they migrated from Ruby to the BEAM, they were able to reduce their hardware requirements from servers to 5! And Quicken Loans launched a new mortgage offering with a Super Bowl ad , knowing with confidence that their servers would handle the traffic with ease.
In fact, they had trouble load testing it with traditional tools, in the end, they needed to fall back to using Erlang to load test Erlang. This is why using OTP ported to. In this blog post, we are just scratching the surface. Many companies are using Erlang to power their server-side infrastructure. They are doing it to reduce development costs whilst ensuring their systems scale and are resilient. So resilient that their end-users, often focusing on the glitzy app or website, do not even know it is there.
Our Founder and Technical Director, Francesco Cesarini, shares our vision for the future and reveals our refreshed brand. Erlang is a programming language designed to offer concurrency and fault-tolerance, making it perfect for the needs of modern computing. Talk to us about how you can handle more users, safer, faster and with less physical infrastructure demands. Find out how our experts can help you. Community Hub Downloads Webinars Events.
Contact Us. A Solution to a Problem One of the first things I try to find out when I meet a programming language inventor is what problem were they trying to solve when creating the language. Things communicate with messages. Things fail. The OTP Middleware OTP is a set of frameworks, principles, and patterns that guide and support the structure, design, implementation, and deployment of Erlang systems.
Is it still a badly kept secret? The unicode library module helps with converting between various representations of unicode.
Not being able to do this is considered a feature of Erlang. The Erlang book explains this in chapter 1. Having said that, there are common methods to achieve effects similar to destructive update: store the data in a process use messages to manipulate it , store the data in ETS or use a data structure designed for relatively cheap updates the dict library module is one common solution.
The manual page has a complete example showing how to do it. Escript is intended for short, "script-like" programs. A more general way to do it, which also works for older Erlang releases, is to start the Erlang VM without a shell and pass more switches to the Erlang virtual machine.
Here's hello world again:. Save this as hello. Erlang has several mechanisms for communicating with programs written in other languages, each with different tradeoffs. The Erlang documentation includes a guide to interfacing with other languages which describes the most common mechanisms:.
Some of the above methods are easier to use than others. Loosely coupled approaches, such as using a custom protocol over a TCP socket, are easier to debug than the more tightly coupled options such as linked-in drivers.
The Erlang-questions mailing list archives contain many desperate cries for help with memory corruption problems caused by using Erl Interface and linked-in drivers incorrectly A Python implementation of an Erlang hidden node.
Lots of useful utilities in unix can be chained together by piping one program's output to another program's input. Here's an example which rot encodes standard input and sends it to standard output:. There are two completely different ways to communicate with a database. One way is for Erlang to act as a database for another system. The other way is for an Erlang program to access a database.
The former is a "research" topic. If you want to decode them using C programs, take a look at EI. Erlang crash dumps provide information about the state of the system when the emulator crashed. The manual explains how to interpret them. This philosophy is widespread around Erlang projects, in part because the Erlang development environment encourages development by prototyping.
Such prototyping will also allow sensible performance estimates to be made. Code which involves mainly number crunching and data processing will run about 10 times slower than an equivalent C program. This includes almost all "micro benchmarks". Large systems which spent most of their time communicating with other systems, recovering from faults and making complex decisions run at least as fast as equivalent C programs. Like in any other language or system, experienced developers develop a sense of which operations are expensive and which are cheap.
Erlang newcomers accustomed to the relatively slow interprocess communication facilities in other languages tend to over-estimate the cost of creating Erlang processes and passing messages between them. The timer module measures the wall clock time elapsed during execution of a function:. Memory consumption is a bit of a tricky issue in Erlang.
Usually, you don't need to worry about it because the garbage collector looks after memory management for you. But, when things go wrong, there are several sources of information. Starting from the most general:. This gives you a rock-solid upper-bound on the amount of memory the entire Erlang system is using. The shell's i and the pman tool also give useful overview information.
The Erlang runtime also uses memory for other things.
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