bug: java.lang.OutOfMemoryError on Android

[louis123562]

Plugin version:
6.0.2

Platform(s):
Android

Current behavior:
Some users encounter an unsuccessful app start; the app closes immediately after start.

Expected behavior:
The app should start as expected.

Steps to reproduce:
it is hard to reproduce; i cant by my self.

Related code:

Other information:
The queries we run are simple INSERT and SELECT queries with the maximum of about 1024kb of data.

Capacitor doctor:

💊   Capacitor Doctor  💊 

Latest Dependencies:

  @capacitor/cli: 7.0.1
  @capacitor/core: 7.0.1
  @capacitor/android: 7.0.1
  @capacitor/ios: 7.0.1

Installed Dependencies:

  @capacitor/cli: 6.2.0
  @capacitor/android: 6.2.0
  @capacitor/core: 6.2.0
  @capacitor/ios: 6.2.0

[success] iOS looking great! 👌
[success] Android looking great! 👌

[louis123562]

My further investigations show, that this is an alternative behaviour to #603. When my users delete cache and storage in system settings, then reinstall the app, the app works again. We added the flag for backup=false as well; which only helps if the app gets uninstalled.

very interesting behaviour...

[danielcollione]

This error is also occurring in one of my clients...

Installed Dependencies:

@capacitor/cli: 5.3.0
@capacitor/android: 5.7.8
@capacitor/core: 5.7.8
@capacitor-community/sqlite: 5.7.4,

[louis123562]

thx for reminding me for this issue @danielcollione - i found a solution.
This error came up when executing too many queries after each other or at the same time. This happened on app start, when necessary things were loaded from sqlite.

Android seems to shutdown the application, when the RAM fills up way too fast (java claims RAM). It was so fast, that it could not be measured or seen with android studio debugging. Android is very curious about RAM, even if you just want to claim like 100kb in a very short time period, it crashes. Even if the device has 6 Gigabytes or more... Android makes sure, that the device keeps running.

It is worth to read https://developer.android.com/topic/performance/memory-overview and to watch https://www.youtube.com/watch?v=vNGWpZlUOPM to ensure, that your app uses memory efficiently.

In our app, we simply added a check, if the last query was executed more than 30ms and if not, wait for 30ms and try again, like so:

...

function executeQueryOrRun(...){
    if (this.lastQueryExecutionTimestamp + 30 > DateTime.now().valueOf()) {
      await new Promise(resolve => setTimeout(resolve, 30));
      return await this.executeQueryOrRun(formattedQuery, executeRun);
    }

//execute query here

//set timestamp of last query execution
this.lastQueryExecutionTimestamp = DateTime.now().valueOf();

// return query value
...
}

...

Our app does about 10 queries on the app start. Of course, 10 x 30ms = 300ms is a noticeable timespan. I guess you will need to try out. For us, it was also tricky to proof, that this works, because we had no issues on our own devices. We tested it on our users...

At least the crash rate dropped almost to 0.

If you need more information, comment.

[robingenz]

An OutOfMemoryError error in this line means that the amount of data you are reading out is too large. You should use pagination. The plugin cannot change anything here.

sqlite/android/src/main/java/com/getcapacitor/community/database/sqlite/RetHandler.java

Line 92 in 1372166

call.resolve(ret);