ExecutorService Doubles Memory in API<26 Android

[Tony Starkisi]

My app downloads data from a PHP Server using threads from an ExecutorService with ThreadPool size 4. In API 27, the app runs perfectly without causing any OOM exception from the Heap memory. But all the previous API <26 throws OOM.

Below is a simple code example that executes 134 requests and then adds the response to the pool. In API 27 the maximum Heap size, reaches 68 mb. But when i run it with API 19,21,25 e.t.c the maximum Heap Size reaches 123 mb.

When i remove the Log.d("Process response", (response)+""); in API 27 the Heap Size goes down to 10mb. But with API 19, the Heap Size goes to 60mb.

I cant understand why it doubles the size. It looks like in API 19 and above increases memory when adding tasks in the pool and also when holding the reference in the response variable.

Any suggestions?

**Note**
The thread sleep is for the example only to see the maximum Heap size


Thanks

    private ActivityManager activityManager;
    ExecutorService service  = Executors.newFixedThreadPool(4);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        activityManager= (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);;

        final  RequestQueue queue = Volley.newRequestQueue(this);
        String url =".....";
        for(int i =0 ; i<134 ; i++) {
            StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
                    new Response.Listener<String>() {
                        @Override
                        public void onResponse(String response) {
                            method(response);  //0.5mb
                        }
                    }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d("VolleyError", error.toString());
                }
            });
            queue.add(stringRequest);
        }

    }


    public void method(final String response){
            Runnable task = new Runnable() {
                @Override
                public void run() {
                    try {
                        Log.d("Process response", (response)+"");
                        Thread.sleep(200000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
            logHeap("");
            service.execute(task);
    }

[Stephan van Hulst]

From what I can read online, API level 27 (Android Go) focuses on reducing system requirements for the Android OS. The decrease in memory footprint is a deliberate design goal of that release.

[Tony Starkisi]

But the same happens in API 26. Below API 26, memory is doubled. Did you read something about API 26 also?

[Stephan van Hulst]

Not sure, but level 26 is a major release (Android Oreo) so I wouldn't be surprised if they already made big changes.

[Tony Starkisi]

So there is no workaround or fix?

[Stephan van Hulst]

Maybe not keep 134 responses in memory.