Why did I test it?

In my current Java project, I make some use of JavaScript. Performances were quite horrendous with Rhino in java 6 and 7, but in Java 8 there is a brand new JavaScript runtime: Nashorn.

Its principal feature is that it's much faster than Rhino. At last, we're going to be able to execute some serious javascript on the server side. Given the richness of the node.js ecosystem, that's a whole new bunch of tools at our disposal. But will they run fast, or fast enough?

First, why not just run those scripts with node?

There are several things in there. When I do Java, I know that what I do is highly portable. Much more so than in any other language, node.js included. So dragging a dependency on node.js annoy me. Also, it's much easier to communicate with nashorn (give it inputs, get outputs back or even callbacks) than with an external process. But most of all, the stability of the whole ecosystem kind of scares me. npm is broken every other day and more often than not, upgrading anything leads to a whole bunch of problems. The simple fact that this whole thing is not even packaged for Ubuntu leaves me wondering.

What did I test?

So, for a practical test, I wanted to minify javascript libs on the fly. So I took a typical Javascript payload from my website and applied UglifyJS to it. The initial payload is the blind concatenation of all the JS files at my disposal in my repo. That's about 62kb of JavaScript. This is real JavaScript used in a real world application, not some dummy routine.

First of all, the compression result. I have a slightly different script to run on node.js and on Java, but they all give an output of 28909 bytes out of 62498. I used the same options for both: do it all, compress as hell.

Notes: I'm running this on an Ubuntu 14.04LTS with a Q6600, an old quad-core from Intel not hyper-threaded. I've tested Java 1.7.0_11, 1.8.0_05 and 1.8.0_45 (with the optimistic type system enabled in nashorn)

The test

The results of the first run (that's after uglifyjs has been loaded):

• node.js: 910ms
• Java 8u05: 22s
• Java 8u45: 28s
• Java 7: 19s

So, Java 8 is slower than Java 7. Node crushes them pretty hard - and that's quite an understatement. Note that the newer the version of Java, the worse it is. I surely did not expect that. I don't know much about V8 (node js engine), but I know a few things about Java. HotSpot takes its time to optimize the code it runs. Let's do a for loop with 10 iterations and see how much time it takes at the 10th iteration:

• node.js: 600ms - one core used
• Java 8u05: 3.6s - three cores used - about 10.8s cpu time
• Java 8u45: 3s - three cores used - about 12s cpu time
• Java 7: 17s - one core used

Now, this is more interesting. Java 8 is clearly ahead, but still about 6 times slower than node. Java8u45 is a bit ahead on that one. Java7 is still dreadful, but that was expected.

A last note on the cores used. I noticed it during this test because it runs for longer than the first one. Both tests involving Java 7 and node.js take about 100% CPU, which means they use one core (out of my quad core). The test in Java 8 uses about 300% CPU, which means bout three cores. This is also true for the first test of course, but I didn't notice it at first.

Let's do one more test: After 100 compressions, how much time does it take?

• node.js: 560ms, one core used
• Java 8u05: 1.5s, two cores used so about 3s cpu time
• Java 8u45: 2s, three cores used so about 6s cpu time
• Java 7: 17s - one core used

Well, this isn't much of a game changer, but it show one thing: Java 8 takes its time to optimize its shit. The Java8u05 process went from 300% to 200% cpu at around iteration 55. Java8u45 went down to 200% CPU at iteration 140, getting the script done in around 1.3s but that was too late for the iteration 100 threshold.

Even after the 10th iteration, it continues to go faster. And after a while, it only takes two cores, not three. This is less bad for Java 8 than the previous one. Now Java is only 2.7 times slower than node and 5.4 times if you count CPU time.

Edit: Let's do one more test: After 1000 compressions, how much time does it take?

• node.js: 670ms, one core used
• Java 8u05: 1.3s, 1.2 core used
• Java 8u45: 1.1s, 1 core used
• Java 7: 17s - one core used

Yes, you read that correctly, node.js is going slower after 1000 iterations...

Well, the least one can say it's that Java isn't fast... to become fast. The cpu consumption went from 200% to 120% at around iteration 155. My guess is that the extra cores used were due to the optimizer. It seems to be a heck of a lot of work.

Well, now we can say that Java 8 warmed up is a bit less than 2 times slower than node. But it takes a hell of a lot of time to get there. That said, the result isn't bad at all, given all the resources Google did put in its V8 engine. Java is capable to execute JavaScript at a decent speed.

Wrap up

seconds	Iteration 1	Iteration 10	Iteration 100	Iteration 1000
node.js	0.910	0.6	0.56	0.67
Java 8u05	22	3.6	1.5	1.3
Java 8u45	28	3	2	1.1
Java 7	19	17	17	17

After discarding all results above 5s (so discarding Java7 entirely) and discarding iterations above 200 (they don't seem to change anything but for node who keeps climbing a little to 670ms and then stabilizes), here are the numbers:

I don't know about you, but for my server, I'd rather have a curve that does down than a curve that goes up like node. It would seem as if Java8u45 is longer to warm up but gives better results when warmed up. In the end, Java is 1.6x slower than node, so it can execute its share of JavaScript on the server side. Depending on what you need, it might do the trick. It has to warm up though before being that performant.

The other thing I've learned is that if I want to minify my JavaScript on the fly, I'm going to need some sort of caching mechanism, because none of those run times gives me acceptable performance. This mitigates the 1.6x factor between Java8 and nodejs.

I've also learned that I'll need some sort of warmup at startup, not for my app, but for my JVM. I mean, the first guy getting there will have to wait 22 seconds before getting its JavaScript served? No way, thankyouverymuch.

I've tried a little playing with Java9 but it isn't really mature at this point so I won't disclose anything. Results are on par with Java 8u45. I strongly hope Oracle will pull their shit together and optimize this further.

That is unless they decide to enforce their copyrights on the Java API in which case they'll have to license this JavaScript API from Netscape. It seems only fair. Then again, they'll have to get a license for SQL from IBM, or else they'll go out of business.

Oracle, please spend less in lawyers that undermine your core business and more on engineers which will give a chance to your products. My $.02.

A final note on performance

This warmup that we have seen in the graph is a mix of the JVM warmup and Nashorn engine. But mostly, it is Nashorn. This means that if you create an engine every time you need to execute a script, you won't benefit from it. Here is the most simple way to create an engine:

Well, those pesky ScriptEngine objects created? Never discard them, or else you'll discard the entire optimizations with them.

It's the first time for me that a HDD in a raid1/5 array fails on me. I guess there has to be a first time for everything.

Anyways, I have a 6-2TB disk raid5 array for a total capacity of 10TB. I've had that array for now about 5 years. It's filled with 2TB hard disk drives and has been working pretty smoothly for me. 450MB/s read throughput is how I like it. It's even faster than my GB network, so this has never been the culprit in any of my operations.

For the record, I used the tool idle3-tools from cbothamy to reset my sleep time to something worthy. I have WDC green drives (see the picture, which is actually the drive that failed), and their default settings are really nuts. Really nuts.

Also for the record, my boot drive is a single old Maxtor 320GB drive and has nothing to do with mdadm. So if you have issues with booting onto your mdadm array, look no further. This page is not for you.

Now, I've had a failure this morning and I've had to change one of the drive. I have a "regular" box (See here for pics and french text) so there was no hot-swapping involved. But just a 5 minute downtime was good enough for me.

How did I find out about the faulty drive? Well, I have an "Error" section in my conky configuration and it outputs the diff of the regular /proc/mdstat with the initial one. Just logging into my desktop alerted me right away with a big red section that is usually empty right on my desktop. This is important, because if you don't monitor your raid array, it'll fail eventually on more than one drive and you'll lose everything. Note that from time to time, a red section appears in my conky as mdadm runs a routine check of the raid array.

Now, how do you get down to it. First, I needed to figure out which drive in my raid array was faulty. Here was the result of my mdstat file:

First a little explanation. The [UUUUU_] indicates the number of good disks (U) vs. the number of faulty disks (_). Similarly, the 6/5 indicates the number of total disks in the array (6) vs. the number of working disks (5). At last, the (F) next to sdf1 indicates the partifion that isn't available anymore.

Well... clearly one of the drives has made it to heaven, and it was /dev/sdf. Or has it? Could it just be a software glitch? In doubt, I reboot the server to see if things will get better. After a fight against the BIOS to make it boot with a faulty drive, I notice the same thing. I kinda hoped it would be a defect in the disk driver. Alas...

Well, the HDD seems to be dead. Let's remove it.

First, let's remove the drive from the array in mdadm:

This is done and mdadm is now aware that there is no disk /dev/sdf1 anymore. Next, I need to open the box and locate the good drive. Now... which one is it? I have 6 WDC green in my box... Let's list all the drives with their serial number:

Well... The faulty drive doesn't show its serial number anymore. The good news is that I have the serial numbers of the other drives and I'll be able to locate the one that I don't have.

I just opened the box, looked for a drive with a serial number not on my list, swapped it with a new one and put everything back together. Note that I did take care of making sure I did not swap SATA plugs. I wanted to make sure the new drive was on the same SATA plug the faulty one was on. I don't know if it matters.

After booting up, my raid array was in the same state as before shutting down. First, I had to partition the drive the same way the others were partitioned. I ran (as root):

Now, don't get mixed up with your drives. This will effectively erase the partition table of your drive, copying from /dev/sde to /dev/sdf. Depending on your setup, you can lose everything on the target drive. Here it was /dev/sdf, my newly installed drive.

The last thing I needed was to add the new drive to the array:

And that's all... almost. Now mdadm will rebuild the new drive with the data it should contain. It took about 500 minutes for me, a little more than 8 hours, so be patient. This will take time.

A few hours later, and my raid array is slowly recovering from the disaster:

As you can see, I still have 102.6 minutes left.

When everything was done:

I have to say I'm surprised at how smooth everything went. I haven't lost a byte and I still have a spare drive, although I'll need a few others if/when this happens again.

My first experience with mdadm was kind of a disaster, but it was because I used it as my / partition. Debugging it in busybox wasn't a lot of fun. But this time around, everything went smooth.

References

I know, I'm a programmer. And as such, everyday or so of my life for the last 20 years I've written code. Most of it has been thrown away by now, but a good chunk is still alive and kicking. And what happens to this code now? Well, from time to time someone take a look at it and try to think "how am I going to make this code do what I want it to be doing". And if this person finds an answer quickly, the code I wrote was good.

As Dan McKinley puts it very well, the best way for this code to make things easy for other people is to be understandable at first glance. Smart and clever code doesn't meet this standard. Boring code does.

Boring code means code that meets long-established standards. It's boring because those standards have been known for a long time and you're smart! You can do better! Yes, you can, but no, you shouldn't. Because the next person modifying your code won't have a clue about your smart idea of the day.

In the same way, when choosing a library to answer a need you have, before jumping into the latest shiny bandwagon, ask yourself if the old and rock-stable lib everyone knows can do the job. If it can, there is probably no better choice. If and when it fails, you're more likely to have at least a few people onboard that know about that failure. When you push it to the limits, you also have experienced people that can better predict what will happen.

The only exception to this rule is areas in which you innovate, and there should be very few of them. You can't innovate on every front. Because innovation is draining your resources: it is longer to setup, harder to pickup for newcomers, harder to fine tune, more prone to bugs which are harder to debug. Just because it's new and no one has any experience with it. So choose those areas very carefully.

This is where the GTD (Get Things Done) should kick in. Use rock-solid and proven libs. Use rock-solid and proven patterns. You will be more likely to build a rock-solid platform that works without a glitch. And it will be faster and less expensive to build.

java-user-agent-detection is a small lib that gives back information when given a user-agent string. It is fast (under 0.1ms) and optimized. Where you need to go from there:

• The home page.
• The project on GitHub.
• Test your user-agent.

If you want to leave feedback, the comments space below is a good place.

Continuing on my journey to find the proper set of fonts for my website, I was a little surprised to see the way the different vendors handle native fonts in CSS. In this realm, there are three players that handle both the OS and the browser: Apple (Safari on Mac OS and iOS), Microsoft (IE on Windows) and Google (Chrome and their default browser on Android). Their handling of the native fonts is — of course — different. Let's see the different approaches.

Google

Let's start out with the simplest one: Android. There is one font, Roboto. You can target it with the following values: sans-serif, sans-serif-light and sans-serif-condensed for the different variants. There are a few aliases such as Arial (alias to sans-serif) or Georgia (alias to serif) but if you want to target Android you should add the serif-liked syntax for better support. Then you can use font-weight and font-style to target different weight and the italic version. However, you cannot target the sans-serif-light or sans-serif-condensed with CSS attributes. You have to select them with the font-family selector.

So, to target a narrow font, you have to use sans-serif-condensed you cannot use the font-stretch:condensed property. Less options is not good. One font is not good. This is not very rich.

Notes:

• This holds true for both Chrome and the abomination installed by default on Android.
• I haven't tested anything on Chrome OS. Common sense from a vendor perspective would say that it should be similar to Android. Common sense from a product placement perspective dictates that I find it doubtful that a desktop OS would ship with so little fonts installed. All bets are open.

Microsoft

• there are not even a handful of fonts with condensed versions
• none are installed by default, they're installed with MS Office
• no other variation than condensed can be targeted (save the Arial Black oddity which quite doesn't work as expected — see below)
• most fonts are crap anyways

font-weight and font-style work as expected but for the fact that all fonts have only two weight available. Again, Arial Black is the exception, giving one more weight to the Arial family. But if you target it with font-weight:100 (trying to get a thinner version) well, you still end up with Arial Black.

So despite its interesting support for different types of font targeting, IE falls short because of the lack of unity and the lack of nice fonts. While testing, be also aware that not all windows users have MS Office installed, so if you do try to find a machine that doesn't to test your fonts on. MS Office comes along with a bunch of fonts and not everyone has them. This is unfortunate because those are nice fonts...

Apple

Safari doesn't support the font-stretch CSS property so far. To target a narrow/condensed font, you have to target it with its family name. The surprise on both iOS and MacOS is that you can target all variations of most fonts by their family name. Italic, light, black, bold, condensed, every variation has a family name you can target right in the font-family CSS attribute. Now, apart from the stretch, you can also target those with font-weight and font-style. For example, if you specify font-weight:600;font-family:Helvetica-Light, you'll get the regular Helvetica (the bold version of the thin font). With font-weight:700 you'll get the bold version. This is the best of both world, really. Whenever Apple starts supporting font-stretch, Safari will be the sweet spot for font selection. But as it is, it's already the best.

Moreover, Apple's (modern) fonts are declined in a variety of styles (like 5 different thickness; light, thin, regular, medium and bold) allowing better control, and they are pretty nice. So — somewhat unsurprisingly — most sites having paid attention to their fonts and relying on native font stacks will be rendered best on Apple devices.

Mixed platforms

For Firefox, well, things look very much like Chrome. It also depends on the OS. For example, trying to target Arial Narrow on Windows has to be done with font-stretch:condensed;font-family:Arial, but on Linux for example, you have to use font-family:"Arial Narrow". font-stretch:condensed; doesn't do anything on Linux.

How to test?

Testing, as always, is the right thing to do. I've set up a small page that list the fonts available on your browser. You can access this page from an iOS, Android, MacOS and Windows machine to see the fonts available. Then you can build your font-family stack with reasonable confidence. If you don't have all of those machines available, hop on to saucelabs.com to access some of those machines for free. Test the fonts on your browser

All in all, I have found that the worst platform to find fonts for is Windows. But in every case, I've found fonts that I liked for every system without much work. @font-face is not yet something I will consider for any of my websites.

As you discovered with my previous entry, I was looking for nice condensed web fonts (read: native) for my headings. Well, I found plenty for everyone but for Chrome on Windows. Chrome issue is troublesome for me because this combination represent 30% of my traffic right now, by far outweighing other combinations of browser/OS.

How come I couldn't do it? I could do it with IE, Firefox on all platforms and Safari on all its platforms. Even Chrome on non-Windows platforms. It turns out that Chrome does not support the font-stretch: condensed CSS attribute. On other platforms, there are fonts that are condensed and can be targeted by using their name, but alas, Arial Narrow is not a font you can target with Chrome (nor with Firefox), even though IE can target it. Note that Franklin Gothic is in the same situation.

It's the first time Chrome is lagging in terms of features behind IE and Firefox (at least on something I use).

Let's hope Google addresses this problem as Arial Narrow is pretty much everywhere. And it's a pretty nice font, even though Helvetica people have probably left my website by now.

Edit on October 16: It is an issue with Chrome 37. So hopefully it'll get patched soon.

Edit on October 21: Chrome 38 is out. This is fixed.