In Part One of this post, we discussed the Great Concurrency Problem and the promise of Go in taking the throne from Java. Today, I show why Go isn’t going to get us there.
Back in the heady days of C++, if you wanted to add concurrency support to your application, you had to work for it. And I don’t mean just find a few calls and shove them into your application. I mean:
- Find a threading library available on your platform (maybe POSIX, maybe something more nightmarish, maybe even a custom thread library that would run you a few hundred bucks per license)
- Locate the obscure documentation on threading APIs
- Figure out how to create a basic thread
- In the process, read the encyclopedia-sized docs about all the real issues you’ll hit when building threads
- Decode the myriad of options available to you to synchronize your threaded application via header files
- Add the library to your makefile
- Code the example and
- Make it all work
Contrast that with Java:
- Create a Runnable interface
- Implement the run() method
- Call new Thread(myRunnable).start();
- Debug the obscure errors you get after about 6 months of production
Whoa. At least with C++, the Threading Shotgun wasn’t loaded, the safety was on and it was hanging on the wall. You had to do the hard work of loading the gun, removing the safety and pulling the trigger. Java took all that away by handing you the loaded shotgun, safety off. That shotgun is the Great Concurrency Problem.
Java’s great contribution and Achilles Heel, in my opinion, was the choice to make threading so darned easy to do, without making developers innately aware of the implications or difficulties of concurrent programming with the shared memory model. C++ made you wade through all the hard shared-memory stuff just to get to threads, so by the time you wrote one, you at least felt smart enough to give it a go. The concurrency models in Java and C# hide all sorts of ugliness under the covers like shared memory models, caching of values, timing issues, and all the other stuff that the hardware must implement to make these concurrent threads do their jobs. But because we don’t understand those potential pitfalls before we write the software, we blithely assume that the language semantics will keep us safe. And that’s where we fall down.
Write a multi-threaded program in any shared-memory concurrent language and you’ll struggle with subtle synchronization issues and non-deterministic behavior. The timing bugs arising from even moderately concurrent applications will frustrate and annoy the most seasoned of developers. I don’t care if it’s in Java or not–the issues are similar.
My specific beef with Java is the ease with which we can create these constructs without understanding the real problems that plague us down the road. Until we have the right tools to produce concurrent applications in which we can reliably debug and understand their behavior, we can’t possibly benefit from the addition of a new language. In other words, if you want to create a Java killer, you’re going to need to make concurrent programming safer and easier to do. A tall order to say the least.
Enter Google’s Go in November, 2009. The number one feature trumpeted by reviewers is the use of goroutines (the message-based concurrency mechanism for Go) and channels to improve concurrent programming. Initial reviews are mixed at best. But I don’t think we’re anywhere close to killing Java off with this new arrival on the scene for a variety of reasons:
- Go decided to use a foreign syntax to C++, C and Java programmers. They borrows forward declarations from BASIC (yep, you heard me right…BASIC), creating declarations that are backwards from what we’ve been using for close to 20 years. Incidentally, syntax similarity was one of the main reasons C++ programmers easily migrated to Java during the Language Rush of 1995, so this is disappointing.
- Performance benchmarks that put it slower than C++ (and therefore, slower than Java today since Java finally caught up to C++ years ago). OK, I’ll grant you that Java wasn’t fast out of the gate, but Java was also interpreted. Go is statically linked, and not dynamically analyzed at runtime, so it’s not likely to get better immediately.
- A partial implementation of Hoare’s CSP model using message-based concurrency. I almost got excited about this once I finally understood that message passing really makes for safer concurrency. But they didn’t get the model quite right. For example, did you know you can take the address of a local variable and pass that via a channel to another goroutine to be modified? Bringing us right back to the same crappy problems we have in Java and C#. Oh yes. Not that you should do that, but even Java was smart enough to drop the address of operator for precisely that reason.
- A few low-level libraries bundled with language, but just barely enough to be functional for real world applications. Completely AWOL: Database and GUI. (translation: “I get to rewrite database access. One. More Time.” Neat.) Did I mention Java had those during it’s 1.0 release?
- Static linking. OK, I admit I’m an object snob and I like a strongly-typed, dynamically-bound language like Java. I like reflection and dynamic class loading and the fact I can pass strings in at runtime, instantiate objects and execute functions in ways the original code didn’t explicitly define (and yes, I’ve done this in enterprise production systems!). Not with Go, instead we’re back to C++ static linking. What you build is what you get. Dynamic class loading was probably one of the most useful aspects of Java that allowed for novel ways of writing applications previously unseen. Thanks for leaving that one out.
- Excepting Exceptions. Go decided to omit exceptions as the error handling mechanism for execution. Instead, you can now use multiple return values from a call. While it’s novel and perhaps useful, it’s probably a non-starter for the Java crowd used to error handling using exceptions.
This feels like some academic research project that will be infinitely pontificated about for years to come, but not a serious language for enterprise development (obligatory XKCD joke). In short, I’m not impressed. And I kind of wanted to be. I mean this is freakin’ Google here. With the horsepower of Robert Griesemer, Rob Pike, Ken Thompson in one building. The #1 search engine in the world. The inventor of Google Wave that created so much buzz, people still don’t have their Wave Invites yet.
Enterprise Languages should be evolutionary steps in a forward direction. But Go doesn’t really get us anywhere new. And it certain isn’t much of a threat to Java. Sorry Google, maybe you need to give it another go?
* Many thanks to my friend Tom Cargill (who you may know from the “Ninety-Nine Rule“) who reviewed early drafts of these 2 posts and corrected my mistaken notions of concurrency, parallelism, Goroutines and Go syntax. He didn’t stop the bad jokes, though. Sorry about that.