I recently stumbled across this issue while debugging some Javascript. Take the following example code:

var array = [1,2,3,4,5,6,7,8,9,10];
var i = 0;
while(array.length > 0) {
	console.log(i++, array);
	//alert("pause");
	array.pop();
}

If you run it in your browser you would expect to see the following printed (in your Javascript console):

0 [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
1 [1, 2, 3, 4, 5, 6, 7, 8, 9]
2 [1, 2, 3, 4, 5, 6, 7, 8]
3 [1, 2, 3, 4, 5, 6, 7]
4 [1, 2, 3, 4, 5, 6]
5 [1, 2, 3, 4, 5]
6 [1, 2, 3, 4]
7 [1, 2, 3]
8 [1, 2]
9 [1]

However, I instead saw:

1 []
2 []
3 []
4 []
5 []
6 []
7 []
8 []
9 []

The issue seems to be that console.log() does not log straight away. In fact it most likely logs in a background thread for performance reasons. Thus by the time it actually logs the array it has changed. I tested this in Firefox (with Firebug) and it logged everything correctly. I also tried slowing down the loop by adding a alert() call. That fixed the issue at the cost of a popup every iterations.

What really should happen is either

• console.log() should block until the logging is complete
• console.log() should copy all objects to avoid them being changed after log() returns but before they are printed.
• add a console.flush() and make me aware this race condition could occur.

I filed this as a bug report on the Chromium site, but I suspect I should have filed it over at the Webkit site.

For the moment I came up with a “fix”. I copy the array before I log it, so in this case I do the following:

console.log(i++, array.slice(0));

Update: I previously searched for this bug, but didn’t find it before writing this article. However, I have just found someone else had reported it a few days ago:

UPDATE – I reported this bug and it was promptly fixed the next day. Read the bug report for solution on how to fix.

Android 2.2 just came out and along with it came a updated set of SDK tools. I’ve been using these tools on Windows, but today I took my Linux laptop out and I’ve been sat in a coffee shop hyped up on caffeine but completely unproductive because I’m going round in circles with what I think is a bug.

So, I’m trying the new library feature, where you can have a Android library project, which is referenced by one or more Android projects. This allows multiple projects to easily share the same code. The problem is when I set-up my Android project to use a library project I get the following error printed in my eclipse console:

ERROR: Unknown option '--auto-add-overlay'
Android Asset Packaging Tool

and the code fails to compile. If I remove the reference to the library project this error goes away.

The error is coming from the aapt command, which seems to be installed multiple times, once for each SDK version:

$ locate -r "aapt$"
/home/bramp/android-sdk-linux_86/platforms/android-3/tools/aapt
/home/bramp/android-sdk-linux_86/platforms/android-4/tools/aapt
/home/bramp/android-sdk-linux_86/platforms/android-7/tools/aapt
/home/bramp/android-sdk-linux_86/platforms/android-8/tools/aapt

Checking each command I see that only versions 7 and 8 have the –auto-add-overlay option. Both my library and main projects are targeted at Android 1.6 (i.e. android-4). I tried re-targeting my main project to Android 2.2 (i.e. android-8) and the problem seems to go away.

So for the moment this seems an annoyance, but I can live with it by setting my target to 2.2. Hopefully Google will release a fix so I can still use the older targets with the new library feature.

Just a quick update:
I noticed that on Windows all versions of the aapt tool support the ‘–auto-add-overlay’ option. So what I suspect has happened is that someone forgot to update the aapt binary for the old platforms.