Crashed: job_progress_queue
EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x00000003d7fd8a7c
0  Realm                          0x1064071f0 realm::Array::init_from_mem(realm::MemRef) + 12
1  Realm                          0x1064a8294 realm::Group::attach(unsigned long, bool, bool) + 196
2  Realm                          0x1064af054 realm::Group::advance_transact(unsigned long, unsigned long, realm::_impl::NoCopyInputStream&, bool) + 316
3  Realm                          0x10635a9dc void realm::Transaction::rollback_and_continue_as_read<realm::_impl::NullInstructionObserver>(realm::_impl::NullInstructionObserver*) + 588
4  Realm                          0x10635a030 realm::Transaction::rollback_and_continue_as_read() + 28
5  Realm                          0x106359e8c realm::_impl::transaction::cancel(realm::Transaction&, realm::BindingContext*) + 140
6  Realm                          0x1062b3c5c realm::Realm::cancel_transaction() + 264
7  Realm                          0x1061fedd0 -[RLMRealm cancelWriteTransaction] + 36
8  Realm                          0x1061ff3c0 -[RLMRealm dealloc] + 80
9  libobjc.A.dylib                0x1bc9d1358 AutoreleasePoolPage::releaseUntil(objc_object**) + 184
10 libobjc.A.dylib                0x1bc9d1244 objc_autoreleasePoolPop + 232
11 libswiftObjectiveC.dylib       0x1f37ccc2c autoreleasepool<A>(invoking:) + 76
12 MyJobApp                       0x101ad1b98 closure #1 in static Realm.runAsync(in:errorHandler:block:) + 15 (Realm+Helpers.swift:15)
13 MyJobApp                       0x100f97360 thunk for @escaping @callee_guaranteed () -> () + 56 (<compiler-generated>:56)
14 libdispatch.dylib              0x1bc93eec4 _dispatch_call_block_and_release + 32
15 libdispatch.dylib              0x1bc94033c _dispatch_client_callout + 20
16 libdispatch.dylib              0x1bc94685c _dispatch_lane_serial_drain + 568
17 libdispatch.dylib              0x1bc947290 _dispatch_lane_invoke + 400
18 libdispatch.dylib              0x1bc950928 _dispatch_workloop_worker_thread + 584
19 libsystem_pthread.dylib        0x1bc9a7714 _pthread_wqthread + 276
20 libsystem_pthread.dylib        0x1bc9ad9c8 start_wqthread + 8

let job: Job = Job()
job.start()

// Job.swift
public class Job: Object {
    
    @objc public dynamic var id: String = UUID().uuidString
    @objc public dynamic var progress: Double = 0.0
    
    public let tasks: List<Task> = .init()
    @objc public dynamic var runningTask: Task?
    
    public override static func primaryKey() -> String? {
        return "id"
    }
    
    private let jobProgressQueue: DispatchQueue = DispatchQueue(
        label: "job_progress_queue",
        qos: .utility,
        attributes: [],
        autoreleaseFrequency: .inherit,
        target: nil)
    
    public func start() {
        let primaryKey: String = self.id
        let jobProgressQueue: DispatchQueue = self.jobProgressQueue
        //
        // The specifics of `runningTask` are not important, other than the fact that
        // the `progressHandler` block is called frequently to update the caller on
        // its progress from another DispatchQueue.
        //
        runningTask.run(progressHandler: { (progress: Double) in
            Job.update(primaryKey, progress: progress, in: jobProgressQueue)
        })
    }
    
    public static func update(_ primaryKey: String, progress: Double, in dispatchQueue: DispatchQueue) {
        Realm.runAsync(in: dispatchQueue) { (realm: Realm) in
            guard let job: Job = realm.object(ofType: Job.self, forPrimaryKey: primaryKey) else { return }
            try? realm.write {
                guard !job.isInvalidated else { return }
                job.progress = progress
            }
        }
    }
    
}

// Realm+Helpers.swift
extension Realm {
    
    public static func runAsync(in dispatchQueue: DispatchQueue, errorHandler: @escaping (_ error: Swift.Error) -> Void = { _ in return }, block: @escaping (Realm) -> Void) {
        dispatchQueue.async {
            autoreleasepool { // <--- Thread 49: EXC_BAD_ACCESS (code=1, address=0x3d7fd8a7c)
                do {
                    let realm: Realm = try Realm()
                    block(realm)
                } catch {
                    errorHandler(error)
                }
            }
        }
    }
    
}