Proposal: Remove in-memory cache for ParseFile

[wangmengyan95]

Right now we keep a in-memory cache for ParseFile. Doing this will increase ParseFile performance in some cases, but it consumes too much memory. This not only downgrades the whole app's performance in some cases but also prevents us from allowing developers to upload/download file that large than 10 MB. After careful consideration and our recent changes to ParseFile related classes (ParseFileController #73 , ParseHttpBody #70 and ParseFile #116). We propose to remove the in-memory cache for ParseFile.

Pros:

1. Allowing uploading and downloading files that large than 10MB(current limitation)
2. Much less memory usage
   We do an experiment with uploading and downloading 20 1MB ParseFile, see the memory consumption result
   Upload
   With in-memory cache
   
   Without in-memory cache
   

Download
With in-memory cache

Without in-memory cache

Cons:

1. Decrease performance since we use in-disk cache instead of in-memory cache

Please leave your suggestions and feedbacks.
Check PR #116 for details.

[faradaj]

A great way of doing open-source, 👏🏻.
I think this enhancement has two major aspects:
• Making 'ParseFile-operating apps' smoother.
• Making 'ParseFile-operating apps' respectful to Android.
which are musts for good Android apps.
Seems like a fix rather than an enhancement.
+1

[aminelaadhari]

@grantland when the release 1.10.4 is planned ?
99% of our OOM issues are related to this.

[grantland]

@aminelaadhari Unfortunately we don't have an ETA right now for the next release.

In addition, the stacktraces from OOM exceptions generally don't point to the root cause of the problem, but are just signals that you have bad memory management somewhere else in your application. It'd be worthwhile to trace your application to see if there is allocation thrashing somewhere.