Category: Technology

I work in technology sector. And I do round a clock, not only from 9 to 5. It is my bread and butter, it is my hobby, it is the fascination of my life. And with the current rate of change particular in information technology (IT), there is always something new to learn, to try, to talk about. I often post news, thoughts, and reviews. And when I do, this is the category I use.

The tour of International Space Station

This is so cool!  We’ve all seen bits and pieces of space stuff in TV reports.  But this is something else – a complete and through tour of the whole thing.  Well, maybe not complete, as there might be a few places that a webcam is not allowed.  While watching this, I kept thinking of two things.

The first is that there is way more space up there on ISS than I ever thought there was.  There is a possibility that my perception was mostly shaped by videos from the Russian modules, which do seem to be a bit less spacious.

The second is that it’s amazing how the whole secrecy has changed with ISS.  The top of the top technologists and scientists from different countries work together, experiment together, and discover together.  Again, I’m pretty sure there are still plenty of secrets, but there has been a huge progress, I think.

And now that you are done with the video, just pause for the second and think of all the things, all the people, all the technology that had to come through for this even to happen.  Given that space stations don’t grow on trees naturally, but are a product of human genius, I can’t be anything but absolutely amazed by it.

Linux kernel drops 386 support

Slashdot reports that Linux kernel won’t support 386 machines no more.  This is more of a sentimental announcement for nostalgic reasons.  The commentary is hilarious and insightful, as often with Slashdot.

Unfortunately there’s a nostalgic cost: your old original 386 DX33 system from early 1991 won’t be able to boot modern Linux kernels anymore. Sniff.

It’s been a long while sine I saw even a 486 machine.  The last 386 I can remember is probably circa 1998 or so.

Configuring the Apache MPM on Fedora

Configuring the Apache MPM on Fedora

If you take nothing else away from this article, let it be that you should tailor your MPM’s MaxClients setting so that your web server won’t try to allocate more resources than you have available. Better that a visitor wait a moment for a connection than that the server should dip into swap for more memory and bring the entire virtual machine to a crawl.

SPL – Standard PHP Library

I’ve been looking at SPL for some time now.  On one hand, it’s a new addition to PHP core (since version 5.3), so I know how to work without it.  On the other hand, it provides standardized solutions for common problems, and that should be enough reason to start using it.  However, today I came across an interesting article that provides even more reason to use SPL.

In this post I want to investigate the memory usage of PHP arrays (and values in general) using the following script as an example, which creates 100000 unique integer array elements and measures the resulting memory usage:

$startMemory = memory_get_usage();
$array = range(1, 100000);
echo memory_get_usage() - $startMemory, ' bytes';

How much would you expect it to be? Simple, one integer is 8 bytes (on a 64 bit unix machine and using the long type) and you got 100000 integers, so you obviously will need 800000 bytes. That’s something like 0.76 MBs.

Now try and run the above code. You can do it online if you want. This gives me 14649024 bytes. Yes, you heard right, that’s 13.97 MB – eightteen times more than we estimated.

[…]

But if you do want to save memory you could consider using an SplFixedArray for large, static arrays.

Have a look a this modified script:

$startMemory = memory_get_usage();
$array = new SplFixedArray(100000);
for ($i = 0; $i < 100000; ++$i) {
    $array[$i] = $i;
}
echo memory_get_usage() - $startMemory, ' bytes';

It basically does the same thing, but if you run it, you’ll notice that it uses “only” 5600640 bytes. That’s 56 bytes per element and thus much less than the 144 bytes per element a normal array uses. This is because a fixed array doesn’t need the bucket structure: So it only requires one zval (48 bytes) and one pointer (8 bytes) for each element, giving us the observed 56 bytes.

For years I’ve been suffering from PHP’s memory hunger. I’ve had to optimize the code around smaller memory footprints, unset variables, and do all sorts of other messy things, that I normally wouldn’t have in a high-level programming language like PHP. With SPL, it seems, there is more help on the horizon.