Windows build - Lost connection with device

[nelchael730]

It appears as though storing a string over 7500 characters long (an encoded json string in this case) silently crashes Windows builds. The only message logged is "Lost connection with device".

[simc]

What version of Isar are you using?

What version of Flutter are you using?

Do you also see this issue for other platforms?

Is it a specific string or does it happen for any?

Is the string indexed?

[nelchael730]

Sorry for the lack of detail.

I was previously using 3.0.0-dev.8, issues occurred after upgrade to 3.0.0. I have switched back to dev-8 to fix the issue for now.

• What version of Flutter are you using?
  Flutter 3.4
  (Initially I was on Flutter stable channel, switched to master after reading other issues related to "Lost connection with device". Also updated VS to 2022 to update to the latest C++. These updates did not fix the issue.)

• Do you also see this issue for other platforms?
  Issue not seen on other platforms I'm building for - android emulator versions work fine.

• Is it a specific string or does it happen for any?
  Any as far as I can tell.

• Is the string indexed?
  It is not...

I'm sorry for posting this with a lack of detail. I'll test a bit more later to try and figure out what's happening, I'm up against it right now so reverting to previous version and continuing my work for the day.

I'll try it on another laptop as well.

[simc]

Thank a lot! Really appreciate your help!

[i-dentify]

I can confirm this error also within an iOS Simulator AND Android Emulator. For me the error also happens with dev.8. I am using Android Studio on MacOS. The error occurs, when awaiting Isar.open().

class DbContext {
  static DbContext? _instance;
  late Future<Isar> database;

  DbContext._() {
    database = _openDatabase();
  }

  Future<Isar> _openDatabase() async {
    if (Isar.instanceNames.isEmpty) {
      final dir = await getApplicationSupportDirectory();
      return await Isar.open(
          [
            DeliverySchema,
            DeliveryAreaSchema
          ],
          directory: dir.path,
          inspector: kDebugMode
      );
    }

    return Future.value(Isar.getInstance());
  }

  factory DbContext() => _instance ??= DbContext._();
}

And in main():

    final dbContext = DbContext();
    final database = await dbContext.database; // <--- error happens here

Furthermore: I am using runZoneGuarded with a specified onError callback. The app stops without even hitting the first line of that callback.

[simc]

@i-dentify but is it somehow related to the 7500 character issue or a new error? What error message do you see in iOS or Android logs?

Your error does not sound like an Isar issue to me 🤔

[i-dentify]

@leisim Oh damn - I see, that there was this more detailed info in the initial post... I just replied as I have the same final error behaviour then. I do not see ANY error except the message Lost connection to device. And this definitely always happens, when awaiting Isar.open() - I put that specific part at several places within my main() method to ensure, that it's not because of some delayed error of another piece of code.

[simc]

Android locgat shows more information since it does not stop on error.

The iOS simulator would show a crash report if Isar was killing the app

[nelchael730]

I've done a bit more testing though I'm a bit rushed so haven't had time to make an example app - I've been on this current app about 2 months so its a bit of a code swamp...

I suspected that the json strings I was storing might of contained an unusual character or some other encoding issue, but my quick testing has confirmed that the issue exists with any string - my additional test cases were simple strings (AaaaBbbb etc up to 7500) and a base64 encoded image, both crashed the app.

With no errors being output (only the "lost connection" warning), it's hard to trace back. It seems like String columns have a character limit, but since previous versions of Isar did not have any limitations I would hazard a guess and say it feels like a memory issue.

I'll put together a small test app this weekend to test further since my current code examples are not useful for replicating the issue.

[i-dentify]

OK - I tried multiple things as well and I'd finally go along which @nelchael730 guess on a memory issue. The error occurs on my side, since I moved from IsarLink to @embedded. So - what previously has been an entity with a link to hundreds of other entities is now an entity with an embedded list of hundreds of entities. Weird thing though: the error occurs even when I did not run any query at all - the error happened directly on Isar.open(). I now switched back to yesterday's state - where I used IsarLink - and no error at all comes up.

(btw: the reason why I switched to @embedded: I simply did not get the links working - I somehow messed things up there.)

[simc]

@nelchael730 a few lines of test code that show the error would be super helpful. thanks so much!

[noga-dev]

Windows here. When trying to store 10869 bytes the app silently crashes.

Specifically this is the last line of code to run before the silent crash:

  int isar_put_all(
    ffi.Pointer<CIsarCollection> collection,
    ffi.Pointer<CIsarTxn> txn,
    ffi.Pointer<CObjectSet> objects,
  ) {
    return _isar_put_all(
      collection,
      txn,
      objects,
    );
  }

The param values are:
collection: Pointer (Pointer<CIsarCollection>: address=0x1837fe89850) (1664298293328)
txn: Pointer (Pointer<CIsarTxn>: address=0x1831521e9c0) (1662506887616)
objects: Pointer (Pointer<CObjectSet>: address=0x1831524e630) (1662507083312)

[simc]

@noga-dev do you have a sample that reproduces this error? I fail to find one on my machine :(

[simc]

Could you please remove the database and try disabling Windows Security temporarily? It kills my build sometimes

[noga-dev]

@noga-dev do you have a sample that reproduces this error? I fail to find one on my machine :(

@vothvovo

[nelchael730]

OK, i'm back... Sorry I wasn't able to provide any example code, I was ill most of last month.

I've done more testing. From what I can determine it is either not related to string length or I've found a separate issue that is resulting in the same "Lost connection to device." issue.

How to replicate:

start app (windows)
open database inspector
click on floating + button
see database rows added
delete any/all rows from database via inspector
click on floating + button
silent crash

You can restart the app etc and it will always crash. The only way to get it working again is to deleteFromDisk and restart the app. It will work until you delete rows and then forever crashes.

main.dart

import 'dart:math';

import 'package:apptest/collections/bigdata.dart';
import 'package:flutter/material.dart';
import 'package:isar/isar.dart';
import 'package:path_provider/path_provider.dart';

// random string generator
const _chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890';
Random _rnd = Random();
String getRandomString(int length) => String.fromCharCodes(
      Iterable.generate(
        length,
        (_) => _chars.codeUnitAt(
          _rnd.nextInt(_chars.length),
        ),
      ),
    );

Future<void> main() async {
  // get box directory
  final dir = await getApplicationSupportDirectory();
  // open isar db
  var isar = await Isar.open(
    name: 'IsarTest',
    [BigdataSchema],
    directory: dir.path,
    inspector: true,
  );
  // isar.close(deleteFromDisk: true);

  runApp(MyApp(isar: isar));
}

class MyApp extends StatelessWidget {
  final Isar isar;
  const MyApp({
    super.key,
    required this.isar,
  });

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(isar: isar),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({
    super.key,
    required this.isar,
  });
  final Isar isar;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  // create instance and run
  void _pushData() async {
    String string1 = getRandomString(1500);

    final newData = Bigdata()
      ..data1 = string1
      ..data2 = string1
      ..data3 = string1;

    await widget.isar.writeTxn(() async {
      await widget.isar.bigdatas.put(newData); // insert & update
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: const Text('Test PAge Description'),
      floatingActionButton: FloatingActionButton(
        onPressed: _pushData,
        child: const Icon(Icons.add),
      ),
    );
  }
}

bigdata.dart

import 'package:isar/isar.dart';

part 'bigdata.g.dart';

@collection
class Bigdata {
  Id id = Isar.autoIncrement; // you can also use id = null to auto increment

  late String data1;
  late String data2;
  late String data3;
}

[nelchael730]

Is there any progress with this?

To be honest I'm fine using the dev version but i'm now at a point where i'm struggling with not having access to the isar inspector since it stopped working when version 3 was released...

Is ther any way at all to use the inspector with the dev versions anymore?

[ductranit]

I'm having the same issue. Can't run on windows because my data is very large.
I can see someone post the sample to reproduce here #827 (comment)
Just wonder do we have any workaround now?

[simc]

A fix is ready. I'll release a new version very soon!

[hiennguyen1001]

A fix is ready. I'll release a new version very soon!

@leisim I've updated Isar version 3.0.3 for this example and run a Window build, it crashes the first time you open an Isar instance. Please check your new version with the example above.

[StevenGolhen]

I also confirm, that the fix did not solve the problem either with my example #827