1

This question might be related to another question I asked some time ago. However, the situation is now a bit different.

I'm currently developing an Android app with Xamarin that communicates via a Wi-Fi connection with some custom hardware containing a sensor. The job of my app is to retrieve the sensor data from the hardware and store it on the phone without displaying it (thus there is no rendering taking place). I would like to receive a continuous stream of data with equidistant temporal distances between all measurements. Unfortunately, this is not the case as the following graph, depicting the time it took to retrieve a measurement after another in milliseconds, clearly shows: Plot illustrating the temporal distances between my measurements

My initial guess was that those peaks (ranging up to 2500 ms) correlate with the garbage collection cycles and thus decided to experiment a bit. I tried the following combinations concerning the memory heap and GC algorithms so far:

  1. bridge implementation = tarjan; nursery size=256mb; soft heap limit=512mb
  2. bridge implementation = old; nursery size=256mb; soft heap limit=512mb
  3. bridge implementation = new; nursery size=256mb; soft heap limit=512mb

All combinations of those parameters lead to similar results. Concurrent GC is enabled. Do you have any further ideas what could cause those temporal peaks?

Update 1

The code I'm using still looks similar to the code I used in my previous question:

[...]
int timeout = 1000;
while (ShootContinuously) {
    FrameCounter++;
    CancellationToken cancellationToken = new CancellationToken();
    var task = GetDataAndUpdateUIForContinuousShootingAsync(MyDisplayPlot, FrameCounter, StartTime, mainPage);
    if (await Task.WhenAny(task, Task.Delay(timeout, cancellationToken)) == task) {
        // Task completed within timeout.
        // Consider that the task may have faulted or been canceled.
        // We re-await the task so that any exceptions/cancellation is rethrown.
        await task;
    } else { // timeout/cancellation logic
        Debug.WriteLine("Task is taking too long!");
        await Client.DisconnectAndStopReadTaskAsync();
        Client = null;
        GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
        GC.Collect();
        GC.WaitForPendingFinalizers();
        Client = new MyClientSocket();
        await Client.ConnectAndStartReadTaskAsync();
        continue;
    }
}
await Client.DisconnectAndStopReadTaskAsync();

The only difference is that I don't perform any UI updates any more.

Update 2

I sometimes see the following output:

> 04-10 18:17:12.501 D/Mono    ( 8751): AOT: image 'System.IO.dll.so'
> not found: dlopen failed: library not found
> 04-10 18:17:12.503 D/Mono    ( 8751): AOT: image
> '/Users/builder/jenkins/workspace/xamarin-android-d15-9/xamarin-android/external/mono/sdks/out/android-armeabi-v7a-release/lib/mono/aot-cache/arm/System.IO.dll.so'
> not found: dlopen failed: library not found
> 04-10 18:17:12.503 D/Mono    ( 8751): Config attempting to
> parse: 'System.IO.dll.config'. 04-10 18:17:12.503 D/Mono    ( 8751):
> Config attempting to parse:
> '/Users/builder/jenkins/workspace/xamarin-android-d15-9/xamarin-android/external/mono/sdks/out/android-armeabi-v7a-release/etc/mono/assemblies/System.IO/System.IO.config'.Loaded
> assembly: System.IO.dll [External]

Could this be related to my problem?

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