Realm initial sync stucking on 'Pending' when a collection is big

I have a database of ~250mb. When I open a synced realm on the client I subscribe to a class of objects and I add a listener to wait for the sync to complete.

My problem is that, on Android simulator, the subscription doesn’t go on and the last state I can track is ‘Pending’.

This issue seems to appears only on Android Emulator but I had the same issue, with a ~1Gb database also on a Galaxy S9. I’m worried that this isn’t the best way to do initial sync but I can’t find any solutions provided by Realm to such a scenario.

Code Sample

await this.susbscribeAndSyncTo(this.realm_instance.objects("Cliente"), "Cliente") // This is where the sync begin

static susbscribeAndSyncTo = async (object, object_name) => {

        var subscription = object.subscribe()

        return new Promise((resolve, reject) => {
            subscription.addListener((subscription, state) => {
                if (this.checkSubscriptionState(state, object_name)) {
                    try {
                        subscription.removeAllListeners()
                    } catch (e) {
                        console.log(e.message)
                    }
                    resolve(true);
                }
            })
        });

    }
    static checkSubscriptionState = (state, object_type) => {

        switch (state) {
            case Realm.Sync.SubscriptionState.Creating:
                logIfDebug(this.DEBUG,"Creo la subscription per", object_type)
                // The subscription has not yet been written to the Realm
                break;
            case Realm.Sync.SubscriptionState.Pending:
                logIfDebug(this.DEBUG,"Attendo l'arrivo dei dati", object_type)
                // The subscription has been written to the Realm and is waiting
                // to be processed by the server
                break;
            case Realm.Sync.SubscriptionState.Complete:
                logIfDebug(this.DEBUG,"I dati sono sincronizzati con il server", object_type)
                // The subscription has been processed by the server and all objects
                // matching the query are in the local Realm
                return true

                break;
            case Realm.Sync.SubscriptionState.Invalidated:
                logIfDebug(this.DEBUG,"La sottoscrizione ai dati è stata invalidata", object_type)
                // The subscription has been removed
                break;
            case Realm.Sync.SubscriptionState.Error:
                logIfDebug(this.DEBUG,"C'è stato un errore nella sincronizzazione con il server", object_type)
                break;

            default:
                logIfDebug(this.DEBUG,"Mmmm")
                break;
        }

        return false

    }

Version of Realm and Tooling

• Realm JS SDK Version: 2.29.2
• Node or React Native: 0.60
• Client OS & Version: Android Emulator
• Which debugger for React Native: ?/None

[cbush]

It seems not all SDKs have this functionality yet. I can update the JS code examples for now (see draft), but updating the general docs will just make it more confusing. I will hold off for now.

[kneth]

@cbush It has been released in Realm Cocoa v3.16.0 and Realm Java v5.13.0.