Lots of garbage collection in a listview

Question

I have a ListView that uses a custom adapter. The custom adapter's getView uses all the recommended practices:

@Override public View getView(int position, View convertView, ViewGroup parent) {     SuscriptionsViewsHolder holder;     ItemInRootList item = mItemsInList.get(position);      if (convertView == null) {          convertView = mInflater.inflate(R.layout.label, null);           holder = new SuscriptionsViewsHolder();          holder.label = (TextView) convertView.findViewById(R.id.label_label);          holder.icon = (ImageView) convertView.findViewById(R.id.label_icon);          convertView.setTag(holder);     } else {         holder = (SuscriptionsViewsHolder) convertView.getTag();     }      String text = String.format("%1$s (%2$s)", item.title, item.unreadCount);     holder.label.setText(text);     holder.icon.setImageResource(item.isLabel ? R.drawable.folder : R.drawable.file );      return convertView; } 

However when I scroll, it is sluggish because of heavy garbage collection:

GC_EXTERNAL_ALLOC freed 87K, 48% free 2873K/5447K, external 516K/519K, paused 30ms GC_EXTERNAL_ALLOC freed 7K, 48% free 2866K/5447K, external 1056K/1208K, paused 29ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2866K/5447K, external 1416K/1568K, paused 28ms GC_EXTERNAL_ALLOC freed 5K, 48% free 2865K/5447K, external 1600K/1748K, paused 27ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2865K/5447K, external 1780K/1932K, paused 30ms GC_EXTERNAL_ALLOC freed 2K, 48% free 2870K/5447K, external 1780K/1932K, paused 26ms GC_EXTERNAL_ALLOC freed 2K, 48% free 2870K/5447K, external 1780K/1932K, paused 25ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2870K/5447K, external 1780K/1932K, paused 26ms GC_EXTERNAL_ALLOC freed 3K, 48% free 2870K/5447K, external 1780K/1932K, paused 25ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2870K/5447K, external 1780K/1932K, paused 29ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2870K/5447K, external 1780K/1932K, paused 29ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2871K/5447K, external 1780K/1932K, paused 28ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2871K/5447K, external 1780K/1932K, paused 26ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2870K/5447K, external 1780K/1932K, paused 27ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2870K/5447K, external 1780K/1932K, paused 29ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2870K/5447K, external 1780K/1932K, paused 26ms GC_EXTERNAL_ALLOC freed <1K, 48% free 2870K/5447K, external 1780K/1932K, paused 34ms 

What seems to be wrong?

EDIT @12:47 GMT:

In fact it's slightly more complicated than this. My app UI is based on 2 parts. One is the brain of a screen, creating the views, handling user input, etc. The other is a Fragment if the device has android 3.0, otherwise it's an Activity.

The GC happened on my Nexus One 2.3.3 device, so using the Activity. I don't have my Xoom with me to test the behaviour with a Fragment.

I could post the source if required, but let me try to explain it :

• RootList is the brain of the UI. It contains :
  • a List<> of items that will be placed in the ListView.
  • a method that builds this list from a SQLite db
  • a custom BaseAdapter that contains basically only the getView method pasted above
• RootListActivity is a ListActivity, which:
  • uses an XML layout
  • the layout has of course a listview with id android.id.list
  • the Activity callbacks are forwarded to the RootList class using an instance of RootList created when the activity is created (constructor, not onCreate)
  • in the onCreate, I call RootList's methods that will create the list of items, and set the list data to a new instance of my custom class derived from BaseAdapter

EDIT on may 17th @ 9:36PM GMT:

Here's the code of the Activity and the class that does the things. http://pastebin.com/EgHKRr4r

Answer 1

I found the issue. My XML layout for the activity was:

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="fill_parent"     android:layout_height="fill_parent">      <include android:id="@+id/rootlist_header" layout="@layout/pre_honeycomb_action_bar" />      <ListView android:id="@android:id/list"         android:layout_below="@id/rootlist_header"         android:layout_width="fill_parent"         android:layout_height="fill_parent"         android:layout_weight="1"         android:textColor="#444444"         android:divider="@drawable/list_divider"         android:dividerHeight="1px"         android:cacheColorHint="#00000000" />  </RelativeLayout> 

If I remove the android:cacheColorHint="#00000000", the heavy GC is out, and the scrolling is smooth! :)

I don't really know why this parameter was set, because I don't need it. Maybe I copypasted too much instead of actually build my XML layout.

THANK YOU for your support, I really appreciate your help.