Repro app for storesafe/cordova-sqlite-storage#299

This is a small Cordova app which exhibits the problem reported as litehelpers/cordova-sqlite-storage#299.

The problem is at the intersection of cordova-sqlite-storage and PouchDB; it's not clear where it lies exactly except that it does not happen with PouchDB and native WebSQL.

Run

• Clone this project
• cordova prepare
• open platforms/ios/SqliteCordovaIssue299.xcodeproj
• Run on a device or in the simulator
• Tap "start" in the app
• Observe memory use in Xcode

What is it doing?

• It bulk loads 8000 records into a PouchDB database backed by the PouchDB websql adapter and cordova-sqlite-storage.
• It defines 8 map-reduce indexes with various levels of complexity in the same database.
• It triggers building each of the indexes in turn.

Observations

You will see a spike in memory use when the 8th index starts building. Curiously, it appears to be dependent on both the number of indexes before it and the content of the index itself. Remove the other indexes and there's no spike. Move the 8th index earlier in the process and there is no spike (or at least a less visible one).

Running with more or less data

In order to be runnable either with or without the plugin, this app uses 8k records by default. You can add more like so:

• Edit data/generate_data.rb.
• Change the constant LIMIT=8_000 to another number. There is raw data included for up to 30000 records.
• Run data/generate_data.rb. (It should work fine with the OS X system ruby.)
• Run cordova prepare
• Run via Xcode as above.

The spikes are more visible with more data, though I have not yet seen the OS kill this app for excess memory use in the way I have seen with my real app.

Running with native WebSQL

• cordova plugin remote cordova-sqlite-storage
• cordova prepare
• With via Xcode as above

With native WebSQL, there is less overall memory use and the use curve appears less spiky.