Asynctask doesnt work after too many rows retrieved

Issue

I am doing an app where I synchronize my online DB to the offline DB everytime the user logs in. The table is dropped in offline, recreated then new rows gets added ( Its neccessary to drop it and add new instead of just checking and adding the rows that are not in the table already). I had about 200 rows in my online table and they are synchronised to my offline table relatively fast (in the background, then I tried 3000 and it was still processing. But When I generated 90 000 rows and tried to synchronize it to my offline DB it wouldnt move.

The log in onPreExecute() executed, but none of the logs in my doInBackground. json is not null. For each retrieved row I am adding a row in offline.

Anyone know what could be the issue? I tried adding LIMIT 200 in my PHP Scripts and still didnt do it, which was weird, cause when I had 200 rows it executed, but when I limit the output to 200 it does not. Thank you for any answers, that would bring me closer to the solution.

public class SyncVykresToOffline {

    String DataParseUrl = "/scriptsforandroidapplicationofflinemode/SyncVykresToOffline.php";
    JSONObject json = null;
    String str = "";
    HttpResponse response;
    DBHelper dbh;
    private Context mContext;
    public static boolean syncedvykres = false;
   int k = 200;

    public SyncVykresToOffline(Context context) {
        mContext = context;
        dbh = new DBHelper(mContext);
    }


    public class SyncVykres extends AsyncTask<Void, Void, Void>
    {
        public Context context;


        public SyncVykres(Context context)
        {
            this.context = context;
        }

        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();
            Log.i("Poradie_zacal","ano");
        }

        @Override
        protected Void doInBackground(Void... arg0)
        {




            HttpClient myClient = new DefaultHttpClient();
            HttpPost myConnection = new HttpPost(DataParseUrl);


            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("limit", String.valueOf(k)));
            try {
                myConnection.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            } catch (UnsupportedEncodingException e1) {
                e1.printStackTrace();
            }

            try {
                HttpResponse response = myClient.execute(myConnection);
            } catch (IOException e1) {
                e1.printStackTrace();
            }


            try {
                response = myClient.execute(myConnection);
                str = EntityUtils.toString(response.getEntity(), "UTF-8");

            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

            int i = 0;
            try{

               int vykres_version;

                JSONArray jArray = new JSONArray(str);
                json = jArray.getJSONObject(i);
                Log.i("Poradie_json",String.valueOf(jArray.length()));

                String
                        Nazov_vykresu;


                int Version,
                        ID_vykres,
                        ID_stav,
                        ID_zakazka,
                        Poradie;

                if(json == null) {
                    Log.i("Poradie","son is null");
                }


                while(json != null) {
                    Log.i("Poradie","been here");
                    ID_vykres = Integer.parseInt(json.getString("ID_vykres"));
                    vykres_version = dbh.getVykresVersion(ID_vykres);
                    Nazov_vykresu = json.getString("Nazov_vykresu");
                    ID_stav = Integer.parseInt(json.getString("ID_stav"));

                    ID_zakazka = Integer.parseInt(json.getString("ID_zakazka"));
                    Version = Integer.parseInt(json.getString("Version"));
                    Poradie = Integer.parseInt(json.getString("Poradie"));
                    Log.i("Poradie",json.getString("Poradie"));

                    dbh.SyncVykresToOffline(new technicky_vykres(ID_vykres,Nazov_vykresu,ID_stav,ID_zakazka,Version,Poradie));

                    i++;
                    json = jArray.getJSONObject(i);
                }



            } catch ( JSONException e) {
                e.printStackTrace();
            }

            catch (Exception e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return null;
        }
        protected void onPostExecute(Void result)
        {
            syncedvykres = true;
        }
    }
}

Edit: added Logcat logs.

06-25 20:36:07.013 8278-8308/com.example.chris.normitapplication W/System.err:     at org.json.JSON.typeMismatch(JSON.java:111)
        at org.json.JSONArray.<init>(JSONArray.java:96)
        at org.json.JSONArray.<init>(JSONArray.java:108)
        at com.example.chris.normitapplication.offline.SyncVykresToOffline$SyncVykres.doInBackground(SyncVykresToOffline.java:102)
        at com.example.chris.normitapplication.offline.SyncVykresToOffline$SyncVykres.doInBackground(SyncVykresToOffline.java:44)
        at android.os.AsyncTask$2.call(AsyncTask.java:292)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)

Edit 2: added PHP Script from where the JSON array is retrieved from:

<?php

include 'DatabaseConfig.php';

$conn = mysqli_connect($HostName,$HostUser,$HostPass,$DatabaseName);


if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}


mysqli_set_charset($conn,"utf8");


$vykres = array();



$sql = "SELECT * FROM `technicky_vykres`";

$result = mysqli_query($conn, $sql) or die("Error in Selecting " . mysqli_error($conn));



while($row =mysqli_fetch_assoc($result))
{
    $emparray[] = $row;
}


echo json_encode($emparray);

$conn->close();
?>

Issue identified when logging STR:

<html>
    <head><title>502 Bad Gateway</title></head>
    <body bgcolor="white">
    <center><h1>502 Bad Gateway</h1></center>
    <hr><center>openresty</center>
    </body>
    </html>

Solution

Upon realizing that the PHP script stopped working because too many rows & columns were retrieved instead of * I only Selected data that I truly needed (about 1/3 of all columns), then I added a where clause where ID would be above the number I sent from post and I keep repeating the script until finally the response is not "null".

Thank you for everyone who contributed to finding the solution.

Answered By - Chris Fodor