Android NDK Sensor strange report interval to event queue

I try to access the accelerometer from the NDK. So far it works. But the way events are written to the eventqueue seems a little bit strange.

See the following code:

ASensorManager* AcquireASensorManagerInstance(void) {
    typedef ASensorManager *(*PF_GETINSTANCEFORPACKAGE)(const char *name);
    void* androidHandle = dlopen("libandroid.so", RTLD_NOW);
    PF_GETINSTANCEFORPACKAGE getInstanceForPackageFunc = (PF_GETINSTANCEFORPACKAGE) dlsym(androidHandle, "ASensorManager_getInstanceForPackage");
    if (getInstanceForPackageFunc) {
        return getInstanceForPackageFunc(kPackageName);
    }

    typedef ASensorManager *(*PF_GETINSTANCE)();
    PF_GETINSTANCE getInstanceFunc = (PF_GETINSTANCE) dlsym(androidHandle, "ASensorManager_getInstance");

    return getInstanceFunc();
}

void init() {
    sensorManager = AcquireASensorManagerInstance();
    accelerometer = ASensorManager_getDefaultSensor(sensorManager, ASENSOR_TYPE_ACCELEROMETER);

    looper = ALooper_prepare(ALOOPER_PREPARE_ALLOW_NON_CALLBACKS);

    accelerometerEventQueue = ASensorManager_createEventQueue(sensorManager, looper, LOOPER_ID_USER, NULL, NULL);

    auto status = ASensorEventQueue_enableSensor(accelerometerEventQueue,
                                                 accelerometer);
    status = ASensorEventQueue_setEventRate(accelerometerEventQueue,
                                            accelerometer,
                                            SENSOR_REFRESH_PERIOD_US);
}

That's how I initialize everything. My SENSOR_REFRESH_PERIOD_US is 100.000 - so 10 refreshs per second. Now I have the following method to receive the events of the event queue.

vector<sensorEvent> update() {
    ALooper_pollAll(0, NULL, NULL, NULL);

    vector<sensorEvent> listEvents;
    ASensorEvent event;

    while (ASensorEventQueue_getEvents(accelerometerEventQueue, &event, 1) > 0) {
        listEvents.push_back(sensorEvent{event.acceleration.x, event.acceleration.y, event.acceleration.z, (long long) event.timestamp});
    }

    return listEvents;
}

sensorEvent at this point is a custom struct which I use. This update method gets called via JNI from Android every 10 seconds from an IntentService (to make sure it runs even when the app itself is killed). Now I would expect to receive 100 values (10 per second * 10 seconds). In different tests I received around 130 which is also completly fine for me even it's a bit off. Then I read in the documentation of ASensorEventQueue_setEventRate that it's not forced to follow the given refresh period. So if I would get more than I wanted it would be totally fine.

But now the problem: Sometimes I receive like 13 values in 10 seconds and when I continue to call update 10 secods later I get the 130 values + the missing 117 of the run before. This happens completly random and sometimes it's not the next run but the fourth following or something like that.

I am completly fine with being off from the refresh period by having more values. But can anyone explain why it happens that there are so many values missing and they appear 10 seconds later in the next run? Or is there maybe a way to make sure I receive them in their desired run?

from Android NDK Sensor strange report interval to event queue