Myth: Android devices need task killers

One of the most popular applications in the Android Market is a task killer. But in fact, Android 2.1 does not need task killers

In the early days of Android, there were widespread user reports that Android-powered smartphones had battery drain problems, slowdowns, or hangs for lack of memory after prolonged use. To meet this need, developers wrote task-killing applications, which quickly became popular on the Android market.

When I got my HTC Incredible running Android 2.1, a G1-owning friend advised me not only to install the popular Advanced Task Killer application on my phone, but also to pay for the version without ads. I took half his advice and installed the free version and the free TaskOS. Then I monitored memory usage and battery usage on my device over time.

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I found the results to be interesting but puzzling. A freshly booted Incredible had more than 200MB of RAM free; with many applications running that would drop to less than 50MB free. The task killer could restore most of the free memory at first, then less and less over time. Eventually, I would turn the phone off and start from scratch.

I passed my friend's gem of wisdom along to a mailing list to which I subscribe, only to be authoritatively corrected. Not only does Android 2.1 not need task killers, they often do more harm than good by killing essential processes without respecting dependencies. This leads to bug reports about how Android is broken, when in fact all that's broken is that the system has granted too much power to applications, enabling one to kill another. In Android 2.2, that privilege will be reserved to the system, as I understand it. Dianne Hackborn has written a blog post explaining in-depth how Android process management works.

Experimentalist that I am, I tried running my Incredible without ever killing a task, while still monitoring memory usage and battery usage over time as I had done before. There was no difference in battery life. The free memory would drop below 50MB and then oscillate somewhat, as the Android system took care of maintaining the RAM pool by killing processes that weren't hosting live activities or services all by itself. In the long term, no difference.

Wait, there was one difference: the task killer started taking longer and longer to list the running processes. That was easy to fix because I had proved to myself that the task killer was useless, so I stopped running it.

One of the Android task killers, TaskOS, claims to be about multitasking more than task killing. I found that on the Incredible it couldn't actually switch to many tasks -- instead, it put up a message saying that the operation had been forbidden by the operating system. I'm not running it any longer, either.

Tip: On the Incredible, pressing and holding the Home key will bring up a box showing the last six applications run. You can switch to any icon shown reliably. But using this mechanism is only slightly more convenient than simply tapping the application's icon on a home screen or the All Programs list. After all, you needn't fear running multiple copies of an application -- Android is not Windows.

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