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POLots of GC when scrolling ListView (with holder pattern)
 

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  1. POLots of GC when scrolling ListView (with holder pattern)
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    <p>It's a similar question to <a href="https://stackoverflow.com/questions/5977718/lots-of-garbage-collection-in-a-listview">this</a>, but the solution doesn't work.</p> <p>The problem is that the scrolling of <code>ListView</code> is very sluggish which is because of lots and lots of GCs. I use holder pattern (view caching) as you can see in the code below:</p> <pre><code>public View getView(int position, View convertView, ViewGroup parent) { ViewHolder holder; if (convertView == null) { convertView = mInflater.inflate(R.layout.eventrow, parent, false); holder = new ViewHolder(); holder.title = (TextView) convertView.findViewById(R.id.eventTitle); holder.place = (TextView) convertView.findViewById(R.id.eventPlace); convertView.setTag(holder); } else { // Get the ViewHolder back to get fast access to the TextView // and the ImageView. holder = (ViewHolder) convertView.getTag(); } // Bind the data efficiently with the holder. holder.title.setText(((EventItem) getItem(position)).getTitle()); holder.place.setText(((EventItem) getItem(position)).getPlace_name()); return convertView; } </code></pre> <p>I removed <code>cacheColorHint</code> and custom selectors from my listview and from rows:</p> <pre><code>&lt;ListView android:id="@+id/android:list" android:layout_width="fill_parent" android:layout_height="fill_parent" /&gt; </code></pre> <p>This is how the log looks like:</p> <pre><code>08-20 19:36:24.286: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed 364K, 46% free 3944K/7239K, external 1196K/1445K, paused 54ms 08-20 19:36:24.356: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed 228K, 49% free 3716K/7239K, external 1721K/1970K, paused 52ms 08-20 19:36:24.456: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed 5K, 49% free 3726K/7239K, external 2214K/2463K, paused 50ms 08-20 19:36:24.546: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed 2K, 49% free 3726K/7239K, external 2214K/2463K, paused 43ms 08-20 19:36:24.636: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed 2K, 49% free 3726K/7239K, external 2214K/2463K, paused 44ms 08-20 19:36:24.696: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 50ms 08-20 19:36:24.766: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 46ms 08-20 19:36:24.846: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 46ms 08-20 19:36:24.906: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 46ms 08-20 19:36:24.986: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 46ms 08-20 19:36:25.056: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 47ms 08-20 19:36:25.136: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 46ms 08-20 19:36:25.196: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 46ms 08-20 19:36:25.296: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 48ms 08-20 19:36:25.356: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3726K/7239K, external 2214K/2463K, paused 43ms 08-20 19:36:34.596: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed 7K, 49% free 3740K/7239K, external 2214K/2463K, paused 51ms 08-20 19:36:34.656: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed 1K, 49% free 3739K/7239K, external 2214K/2463K, paused 50ms 08-20 19:36:34.746: D/dalvikvm(12036): GC_EXTERNAL_ALLOC freed &lt;1K, 49% free 3739K/7239K, external 2214K/2463K, paused 50ms </code></pre> <p><strong>EDIT:</strong> It seems that the problem appears (almost) only when the <code>ListFragment</code> is first inflated. For the first scroll down and then up. After that the GCs are not so often. But sometimes the GCs appear everytime I scroll. I can see no regularity here. <strong>PLUS</strong> I can see the problem on HTC Desire (2.3.7 MIUI) but not on Sasmung Galaxy ACE (2.1). It only gets more confusing...</p> <p><strong>Not so satisfying solution:</strong> When I use </p> <pre><code>android:scrollingCache="false" android:animationCache="false" </code></pre> <p>in my listview it seems ok. But the docs say it should be exactly otherwise if I understand well, so I'm a little bit confused.</p> <p><strong>Where do I make mistake? What to do to have a smooth scrolling listview? Or would disabling <code>scrollingCache</code> have some negative effect which I can't see now?</strong></p>
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    1. COCan you justify your use of caching `TextViews`, when the `static ViewHolder` already keeps that `TextView` in RAM?
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    2. COI'm not sure I follow. I use the `ViewHolder` pattern described e.g. here: http://xjaphx.wordpress.com/2011/06/16/viewholder-pattern-caching-view-efficiently/. Its very sense is caching `TextViews` and not inflating them on every `getView()`. Or am I wrong?
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    3. COReplace `getTitle()` and `getPlace_name()` with static strings. If your problem goes away, your issue lies in those methods.
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