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I have a strange scenario - my dalvik cache is full of dex files - around 150MB of space, but it appears that the operating system does not recognize these files as related to any application.

I installed an App Cleaner and it says my cache is empty.
I went over some applications I use and saw that according to the OS they have no cache, but when I ls the /sd-ext/dalvik-cache directory I see these applications have dex files.

Can I simply run rm /sd-ext/dalivk-cache/* to solve this? Is there any risk?

Tech details:
SD Extension: A2SD+
Rooted: YES

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up vote 3 down vote accepted

Don't confuse the App-Cache with the Dalvik Cache: App Cleaner refers to the App-Cache (e.g. cached files from the internet, aka "webcache", or from other components of the app), while the Dalvik Cache's .dex files are placed on app installation (they are an optimized version of the app code). So basically you compare apples with oranges.

As for your problem: e.g. Titanium Backup offers to cleanup the Dalvik Cache. There might be other apps available providing this feature (e.g. SystemCleanup), but in all cases this requires root -- unless you want to do a factory reset, which completely cleans the Dalvik Cache, amongst others.

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Thanks for the clarification - I tried using Titanium Backup and it also said my dalvik cache is empty - is there any risk in deleting everything there manually? – RonK Oct 2 '12 at 9:54
If you have CWM Recovery installed you can clear the Dalvik cache from there. That said, there shouldn't be an issue removing them manually, but you'll likely need to be root. – pzkpfw Oct 2 '12 at 10:14
Dalvik Cache empty? That's strange for a running system. And no: You can safely purge/wipe it (e.g. from ClockworkMod Recovery). Only consequence is the next boot taking longer, as it automatically re-creates all the required .dex files. This also happens after a factory reset (for the pre-installed apps), by the way. – Izzy Oct 2 '12 at 10:15
Thank you all for the clarifications - I now understand the difference between dalvik and application cache and even better - now I understand my problem was not with the size of the cache but with how much data my applications keep (the whole reason for this question was due to lack of space on my phone's internal memory) – RonK Oct 2 '12 at 19:27
I thought so :) For all of those cases (app cache, app temp data and Dalvik cache), the SystemCleanup app seems to be helpful. Did not use it myself, but description and rating look promising. So hopefully you solved your problem -- and I'm glad I was able to enlighten and help you :) – Izzy Oct 2 '12 at 19:31

root phone delete all files in folder dalvik-cache reboot phone to regenerate cache this deletes useles cache

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