"The Heroes of Java".
Who are you?
"I'm a software guy who lives in Stockholm, Sweden. I've been working
with runtimes for more than ten years, but try to find time to do
hobby hacks so I can understand all modern trends in computer
science. I enjoy all areas of programming, and I'm not afraid to get
my hands dirty with low level programming - kids these day seems to be
afraid of that, which may in the long term doom us all. ;) As one of
the guys who designed the JRockit JVM, I co-authored a book about JVM
internals in 2010, which generated some attention."
Your offical job title at your company?
"Consulting member of technical staff"
Do you care about it?
"To the extent of the name - not at all. I can hardly even tell what it
means - I am, for instance, not a consultant. I care about it to the
extent that it defines a couple of responsibilities and how independent
I can be and so on. And benefits. Probably. I'm not sure it
matters. I've never really sat at my desk one morning and not having
known what to do, regardless of title. The thing to do has usually
turned out the be the right thing and people have rarely complained
I'm slightly skeptical to the whole thing of having titles and
"contributor levels", the way it is implemented in any large
corporation. People are not exactly World of Warcraft characters and
titles in general convey little meaning to an outsider.
At BEA Systems I was a "Staff Engineer" but my business cards said
Do you speak foreign languages? Which ones?
"I am a native Swedish speaker. I speak English fluently and decent
German. My German is great grammatically, but sadly lacking in nouns,
slang and modern expressions. I need to get a German dictionary for my
Kindle and start working my way through it from A to Z. (A Swedish
dictionary would of course go from A to Ö, but Germans treat the
umlauts as modifiers and not as separate letters ;-))
I'm quite good with languages, so I can usually figure out what stuff
means in most latin based languages."
How long is your daily "bootstrap" process? (Coffee, news, email)
"It used to be pretty short. Coffee, read (but don't answer) new
e-mail, done. Then social networks like Twitter appeared. I convince
myself that they actually give me targeted and relevant information
instead of just being time wasters. ;-)
Then the kids arrived. They are definitely the worst planning obstacle
of all. (Yes let's just objectify them as time sinks in the Gantt
chart for the sake of this discussion, I'm really a lovely father. I
promise). Now my bootstrap process is interleaved with waking the kids
up and getting them to school. This means rising at 06.30 and getting
to work at 09.30. My most productive hacking time is in the mornings,
so this is a bit of a handicap. I usually solve this with my wife so I
can pick up the kids from school some days and leave them other
days. If I have a "pick them up" day, I just swallow some coffee and
leave the house at 07.00 and do the rest of the bootstrap at my desk.
Working at home is not possible with children at home, but once they
are out of the house it saves the commute. As I'm going to be on a
distributed team now for a while I suspect I'll be doing more work
from home. The main problem there is that I have such a nice espresso
machine so I usually turn into Cornholio at about 10.30 any given day
I've experimented a bit with my bootstrapping - for example not doing
any "catching up" as the first thing in the morning. For a period of
time I tried getting up at 05.00, gulping down some coffee, hacking
like a maniac for 2 hours and then getting the kids to
school. Interestingly enough I was quite productive, but I don't think
that's something any man should go through."
You have a twitter handle? Why?
"I started using Twitter just by adding people so I could get a
customized stream of news. This mostly contained work related topics
at first, but now I'm including anyone that is fun or
interesting. Twitter has provided me with links to interesting stuff I
wouldn't had found in a wider search domain and has also let me get to
know people who proved to be really important to talk to. I've used
Twitter for job purposes, to exchange information with people I've not
met in "real life", with useful results. Twitter is also a great news
medium, such as when people tweet from the scene of an accident or
I had my Twitter account for about a year until I actually started
posting stuff myself. I post tweets mostly about programming, but not
Whom are you following in general?
"I follow people in the IT business, people in politics and people who
make me laugh. These are not disjoint sets."
Do you have a personal "policy" for twitter?
"I try to keep my tweets in line with "my public character" and to be
(mostly) polite. I keep more personal stuff in closed social networks
instead, but of course there are always exceptions. For example: the
world needed to know about my fight with the flesh eating bacteria in
my arm this summer. THEY NEEDED TO KNOW! ;-)"
Does your company restrict or encourage you with your twitter usage?
"I'm encouraged to do things like tech evangelism, where appropriate,
but it's not an explicit part of my role description.
There is a social networking policy, which involves inside information
and stuff. To be honest I'm not 100% up to date with it, but in
general on Twitter, regardless of corporate policy, if you've got
nothing good to say, it might be better to say nothing at all. The
whole world and all its search engines are listening. "
What's your daily development setup? (OS/IDE/VC/other Tools)
"I tend to work mostly on Ubuntu and Windows on my workstation,
depending on what is required. I use Mac OS on my MacBook. The MacBook
is my own and not company property. My work-at-home setup is a fully
loaded 27" iMac with lots of VMWare images.
My preferred IDE for C/C++ is Microsoft Visual Studio. When we
developed JRockit we used Windows as the development platform because
the IDE was so much more efficient than anything available on
Linux. Visual Studio is truly excellent, both for development and
debugging, with a compiler that produces tight code.
On Linux I do most things (except Java) in plain old Emacs with etags,
old school style. GDB is the debugger.
For Java development I used to be an Eclipse guy, but I've recently been trying out the new Netbeans and find that I quite like it.
For native Mac/iOS projects I have little choice but Xcode, which is
actually useable and not so painful after the release of 4.0, but it's
still nowhere near Visual Studio.
The other tools I need are usually available from the prompt on any
UNIX based system."
Which is the tool providing most productivity to your work?
"Hmm... Emacs? I don't think I ever close it."
Your prefered way of interacting with co-workers?
"Definitely face to face in a room with maybe four people working on
the same thing. I have nothing against distributed work but it has a
tendency to slow things down if you aren't careful. I guess I'm not
the most patient guy in the world.
If you have to work in a distributed setting, e-mail lists is a
horrible way of communicating information. Instant messaging is a
little better. Video messaging, screen sharing over Skype etc, is
quite good. But nothing beats being in the same room and having
whiteboard discussions about things. When I was compiler lead for
JRockit, we were all in one room and things like "all in favor of
rewriting this complex subsystem from scratch - raise your hands" were
totally possible. Doing things like that over a mailing list in six
different time zones naturally gets a lot more complex, especially
since you lose subtle nuances of the communication.
When working on a tightly coupled system you can also infer a lot more
from the "convection currents" of information with people doing the
same thing in the same room. You pick up a stray word in a
conversation about some technical topic and your brain synthesizes
this into part of the big picture without you having to think too much
about it. To clarify, these kinds of work setups are not endless
cubicle farms, but largish offices where 4-5 people share a room. I
like that a lot."
The above should in no way imply that I think distributed projects
suck, they are just harder to synchronize and you get less for free."
What's your favorite way of managing your todo's?
"Make a list. Prioritize it. Do the TODOs one after another. Always
minimize context switches. They kill. I don't think anyone can juggle
many tasks at the same time and be at their maximum level of
productivity. For me "multitasking" usually just means figuring out in
which order to execute the TODOs and not jumping back and forth
Have your e-mail program check for mail every half hour. Not every two
minutes. Half an hour is a pretty good time unit to concentrate on one
If you could make a wish for a job at your favorite company: What would that be?
"I find runtimes and operating systems fascinating. I want some
architectural say in where they go next and have discussions with
industry and academia about technology. At the same time, a day
without looking at assembly code is a bad day. I'm lucky to have a lot
of this already in my job description.
Alternatively I'd like to be on the founding team of another
startup. That's how I've spent some of the happiest time in my
life. Naturally, it's harder with mortgage and kids. The startup would
still have to involve some assembly language ;-)"
You're still programming in Java. Why?
"I'm not just programming in Java. I'm programming in everything. I use
the most appropriate tools that get the job done for any given situation.
Why am I still programming in C? Because it gets the job done for certain
problem sets. Why am I still programming in Haskell? OK - that one has
more to do with personal sexual deviancy I guess.
When it comes to Java as a language it is not going to go away. It is
ingrained in a lot of critical infrastructure in the world. The
runtime is also definitely not going to go away - quite the
opposite. If I may inject a blatant commercial plug here, my book
"Oracle JRockit the definitive guide" talks a bit about how Java and
the JVM became such a ubiquitous platform, and what the intrinsics of
any such platform should be."
What's least fun with Java?
"Java code is extremely voluminous - it takes up so much space compared
to Scala or Ruby or Clojure. Any line of Java that I write seems to
want to break the 80 character boundary. Really simple things are
missing as well, for example, there are no implicit ways of
initializing a map or a collection, boilerplate getter and setter code
for every field needs to be in place and so on.
My main language feature frustration is lack of lambdas. Also,
religiously, I've always been strictly against camel case in any
setting. This goes back to Smalltalk ;)
Type erasure can also be irritating. I guess one of the design
rationales behind generics was that the implementation only needed to
change the compiler. Surprisingly enough it also turns out that
compiling certain type relationships in Java is undecidable. As
someone who majored in theoretical computer science this is sort of
like an itch in my brain that won't go away."
If you could change one thing with Java, what would that be?
"For the language: lambdas and more compactness a la project Coin. We
are on the way there and I think Java 8 will get rid of a significant
part of the frustrations.
For the JVM specification: replace bytecode with something that works
better as a generic intermediate language for a multi language JVM. I
think bytecode will, even despite invokedynamic, soon turn out to be a
bottleneck between the program and the runtime. I rant a bit about it
in my book. "
What's your personal favorite in dynamic languages?
"I like Ruby and Clojure lot. As I'm going to start contributing to
Oracle's Nashorn project now, I guess I'll have to teach myself to
brainwashing process as when I taught myself to appreciate country
music, a skill that was necessary to acquire after marrying my wife."
Which programming technique has moved you forwards most and why?
"Being the nightmare of anyone who wants to define a "process" or
"technique" in software, I must ask you to define "programming
I'll give it a shot anyway - how do I quickly write code that works
and is robust?
Any code that contains sanity checks turns out to be good code: get
into the habit of doing things like putting assertions absolutely
everywhere without thinking about it.
Make sure new features have tests. If you consider something
"untestable" you are doing it wrong. Make it testable! You might even
have to write some kind of whitebox API that exposes system internals
for the test framework to get a test written. In that case, so be
it. Do it!
If you fix a bug by painstakingly whittling a reproducer down to a
small deterministic bit of code - make sure to turn it into a unit
test, tag it with a bug number and get it into the test suite so
you'll never have to do this again.
When programming, avoid explicit parallelism. Things like actors, the
fork/join framework or NSOperationQueue:s in Cocoa help out.
Understand memory management.
Measure and understand where your application spends its time and
Finally, whenever you can: be stateless or use functional
programming. This saves debugging time and produces fewer bugs."
What was the biggest project you've ever worked on?
"The JRockit Java virtual machine."
Which was the worst programming mistake you did?
"I've done my share of evil over the years, so it's hard to single out
any one mistake. I've caused buffer overruns that crashed production
systems, non deterministic function behavior and what not. However,
one particular thing that had long term consequences comes to mind.
At some point we decided that memory allocation in the JRockit
compiler code should have no return value checks and just
automatically bail on failure. I can't even remember why - reducing
code mass, maybe, or a misguided attempt to trap malloc/free bugs in a
global framework that was never written. Anyway, it sucked and turned
into a maintenance nightmare. Always check your return values,
kids. Always. That's another good thing in languages like Java -
try/catch/finally. If you don't have them there is no shortcut. If
the thing can return NULL, you must handle it."