android app cache

i do quite a bit of fiddling around inside the internals of android. i have noticed that occassionally rebooting helps to stabilise the system. although i could never work out the need, as android is essentially linux. but sensing what google wants to do it, i suspect it might be heading the microsoft windows way.. becoming bloatware (it probably already is)!

the next step is to clean out the cache. though you could do so by manually clearing the filesystems, i find it simpler (and safer perhaps) to do so from the recovery. i used clockworkmod. there are two caches - the dalvik cache and the system cache. both can be wiped from recovery. you might reclaim some diskspace too. android will create the required caches from scratch, on the next reboot. this boot will take a rather long time - be warned! watching the phone doesn't help. find something else to do and come back in good time. patience is of essence here.. :-)

there are some other ways to hack out some more space in /data, which is where all user apps are installed.

we can move some app caches to sdcard. this might make those apps slower, if your sdcard is not that fast. for some apps with huge caches, we might be more concerned about reclaiming disk space and sacrificing some speed. note that caches might not necessarily be a bad thing.

let's identifying the apps with the biggest caches. do this after you have been using the phone regularly for a few days without any reboots/cleanup, for best results.

$ du -s /data/data/*/cache | sort -n

if the above command didn't work for you, enable superuser mode and try again.
$ su

the next step is to move some of these caches to the sdcard. we need to decide on some rules to identify the best candidates. i have focussed on the biggest caches where this process actually makes a noticable difference. for me the two apps are market and browser. you need to consider the security implications, as chmod permissions don't work on sdcard fat filesystems, i.e. your sdcard content is world readable.

now move each of them to sdcard, like so

$ mkdir -p /sdcard/cache/browser
$ cd /data/data/com.android.browser
$ rm -r cache
$ ln -s /sdcard/cache/browser cache


note that the app should not be running, not even in the background. go to settings -> applications -> manage applications and verify whether they are running. force close them if necessary. it might be far simpler to boot into recovery and do everything there!