Question

I’m quite new to Android development and was about to finish my first application when I noticed that I have a huge memory leak.

The leak occurs when I start a new activity from within a thread:

private static class CatalogRowOnClickListener implements OnClickListener 
{
    List<CatalogRow> catRows;
    WeakReference<CatalogViewActivity> mActivity;

    CatalogRowOnClickListener(WeakReference<CatalogViewActivity> mActivity) 
    {
        this.mActivity = mActivity;
        catRows = new ArrayList<CatalogRow>();
    }


    public void addCatalogRow(CatalogRow row) 
    {
        catRows.add(row);
    }

    public void onClick(View v) 
    {   
        v.setBackgroundColor(Color.argb(150, 255, 255, 255));


        final ProgressBar linProgressBar = (ProgressBar) v.findViewById(R.id.CatProgressBar);
        linProgressBar.setVisibility(View.VISIBLE);

        final View fv = v;
        final fItem fhitem = findFItem(fv);
        try
        {
            new Thread()
            {


                public void run() 
                {
                    initializeApp();

                }
                public void initializeApp()
                {
                    // Initialize application data here


                    FItemListStore.getItemsFromWebservice(fhitem);
                    boolean isArticleOverview = false;

                    for(FItem item: FItemListStore.fItemViewStorage) 
                    {   
                        if( item instanceof fiArticle ) 
                        {
                            isArticleOverview = true;
                            break;
                        }
                    }


                    Intent intent = new Intent();
                    intent.setClassName("nl.project.Android", "nl.project.Android.Activities.HomeViewActivity");
                    Bundle bundle = new Bundle();

                    if(isArticleOverview)
                    {
                        bundle.putInt("OverviewNr", 1);
                    }
                    else
                    {
                        bundle.putInt("OverviewNr", 0);
                    }
                    intent.putExtras(bundle);

                    //if( mActivity.get() != null )
                        mActivity.get().startActivity(intent);

                    mActivity.clear();

                }
            }.start();
        }
        catch (Exception e) {}

        //Debug.stopMethodTracing();
        //android.os.Debug.stopMethodTracing();
    }     

A HPROF dump of the app after executing this code shows that the thread will always be retained in the heap and grow exponentially. Researching this points towards referencing a context inside a thread causing leaks. So I changed this code a few times until it became this version with only a weak reference in a static class (that’s some things that were mentioned in other posts)

The reason why I want to start the Activity in a thread is because I need to read data from a slow and big webservice, which takes some time. I displayed a loading bar in the activity, highlighting the selected item until the XMLparser is done, and started a new activity afterwards.

Might it be that there is no correct way to start an activity within a thread without causing a memory leak? And, if so, is there another way for me to have the intent started after the xml parser finishes his job?

---

On advice of Vladimir and Heiko, I changed my thread to a AnyncTask. The grow of my retained heap has stopped but the AsyncTask threads I started still remain in the heap. Here’s my new code:

private static class QueryFHTask extends AsyncTask<FredHopperItem, Integer, Boolean> 
 {

     WeakReference<CatalogViewActivity> mActivity;

     QueryFHTask(WeakReference<CatalogViewActivity> mActivity) 
     {
        this.mActivity = mActivity;

     }


     protected void onPreExecute() 
     {

     }
     protected Boolean doInBackground(FItem... items) {
         int count = items.length;
         long totalSize = 0;
         for (int i = 0; i < count; i++) {
             FItemListStore.getItemsFromWebservice(items[i]);
             boolean isArticleOverview = false;

             for(FItem item: FItemListStore.fhItemViewStorage) 
             {  
                if( item instanceof FArticle ) 
                {
                    isArticleOverview = true;
                    break;
                }
             }

             Intent intent = new Intent();
             intent.setClassName("nl.project.Android", "nl.project.Android.Activities.HomeViewActivity");
             Bundle bundle = new Bundle();

             if(isArticleOverview)
             {
                bundle.putInt("OverviewNr", 1);
             }
             else
             {
                bundle.putInt("OverviewNr", 0);
             }
             intent.putExtras(bundle);
             mActivity.get().startActivity(intent);

         }
         return true;
     }

     protected void onProgressUpdate(Integer... progress) {
         //setProgressPercent(progress[0]);

     }

     protected void onPostExecute(Long result) {
         //showDialog("Downloaded " + result + " bytes");
     }
 }

private static class CatalogRowOnClickListener implements OnClickListener 
{
    List<CatalogRow> catRows;
    WeakReference<CatalogViewActivity> mActivity;

    CatalogRowOnClickListener(WeakReference<CatalogViewActivity> mActivity) 
    {
        this.mActivity = mActivity;
        catRows = new ArrayList<CatalogRow>();
    }


    public void addCatalogRow(CatalogRow row) 
    {
        catRows.add(row);
    }

    public void onClick(View v) 
    {   
        v.setBackgroundColor(Color.argb(150, 255, 255, 255));
        final ProgressBar linProgressBar = (ProgressBar) v.findViewById(R.id.CatProgressBar);
        linProgressBar.setVisibility(View.VISIBLE);

        final View fv = v;
        final fItem fhitem = findFItem(fv);     
        new QueryFHTask(mActivity).execute(fhitem);       


    }

To clarify my problem, here’s a copy of one of my HPROF thread overview heap dumps (it’s very hard to read because I was not allowed to post html with links and images like in MAT because of my user level…). The AsyncTask threads retain a heap of 376 or 344. As I browser the application longer, there will be more and more retained heaps from AsyncActivity threads…

Name Instance Shallow Heap Retained Heap Context Class Loader 
main java.lang.Thread @ 0x40027550 80 1.464 dalvik.system.PathClassLoader @ 0x4051ce30 
JDWP java.lang.Thread @ 0x40515838 80 384  
AsyncTask #6 java.lang.Thread @ 0x406ea788 80 376 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #7 java.lang.Thread @ 0x40690178 80 376 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #4 java.lang.Thread @ 0x4068a630 80 376 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #3 java.lang.Thread @ 0x406851f0 80 376 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #5 java.lang.Thread @ 0x405d9f28 80 376 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #2 java.lang.Thread @ 0x40539db0 80 376 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #1 java.lang.Thread @ 0x40517180 80 376 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #8 java.lang.Thread @ 0x4068cdb0 80 344 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #9 java.lang.Thread @ 0x4068b558 80 344 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #10 java.lang.Thread @ 0x4068a178 80 344 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #11 java.lang.Thread @ 0x406639f0 80 344 dalvik.system.PathClassLoader @ 0x4051ce30 
AsyncTask #12 java.lang.Thread @ 0x40661b00 80 344 dalvik.system.PathClassLoader @ 0x4051ce30 
Binder Thread #2 java.lang.Thread @ 0x40519b20 80 344  
Binder Thread #1 java.lang.Thread @ 0x40516868 80 344  
Thread-2 java.util.logging.LogManager$2$1 @ 0x40195298 80 168 dalvik.system.PathClassLoader @ 0x400277f8 
Signal Catcher java.lang.Thread @ 0x40515778 80 160  
Compiler java.lang.Thread @ 0x405158e8 80 152  
HeapWorker java.lang.Thread @ 0x40515618 80 152  
GC java.lang.Thread @ 0x405156d0 80 136  
Total: 21 entries  1.680 7.656 

Answer 1

You should look at AsyncTask , where you do the loading in doInBackground(), set up the status bar in onPreExecute, publish progress updates with publishProgess and then remove the progress bar in onPostExecute.