We are seeing the same issues with our Thunderbolt and the forums are full of reports of crashes for many apps including our own app, ShopSavvy.
HTC and Google area aware of the issue, but until they fix the underlying issue there isn't much app developers can do. Here is the technical explanation from one of our developers:
After much toying, tweaking, and hacking I can safely say that the problem we are encountering with the HTC Thunderbolt can not be fixed from our side of the fence. Doing testing across the Nexus S, Nexus One, Evo, and Thunderbolt I have pinned the problem down to the garbage collection mechanisms on the Thunderbolt; both on the native heap and in the dalvik. On each product screen we place a large image of the product on the lower half of the screen. Each time we create this image an allocation is done on the native heap to hold the actual Bitmap bytes while a small reference object is placed on the dalvik. The error that currently causes ShopSavvy to crash involves the native heap growing until the operating system can no longer allocate anymore space causing the program to crash from the native side of the application, not the dalvik.
In order to free memory on the native heap an Android programmer can either ensure that 1. The bitmap reference on the dalvik is garbage collected which will in turn call the native destructor which will delete the buffer on the native heap or 2. Call the recycle() method on the dalvik Bitmap object which will immediately delete the buffer on the native heap. By calling delete on the native buffer the operating system should then mark that buffer space as reusable and the next allocation should be able to take advantage of the space ensuring that the native heap does not need to grow in size. Therefore, to track down the problem I needed to ensure that both methods were used to keep the native heap under control.
The first round of tests involved ensuring that the Bitmap.recycle() method was called on each product image to ensure that the bitmap should then be immediately recycled. I included a Bitmap.recycle() and a logging statement on activity shutdown methods as well as in the activity finalizer to ensure that the method was called and the bitmap destroyed. On the Thunderbolt calling recycle() on the bitmap never caused an increase in free native heap space. Therefore every time the product screen was visited another 1-2mb would be allocated onto the native heap until the program would get an OOM (Out Of Memory error). If we compare memory consumption of the Evo with the Thunderbolt; after viewing 6 product screens, the native memory usage on the Thunderbolt would grow from 6Mb to 24Mb, where the Evo would grow from 9.9Mb to 14Mb (where it stayed).
The next round of tests determined the activity of the Dalvik garbage collection mechanisms. I went through the code and put printouts in the finalize methods of our product screen objects. This ensures that I get a message every time the dalvik deleted one of these objects from memory. I also wrapped our BitmapDrawables to ensure that the finalize method was being called on them as well. On the Nexus S, Nexus One, and Evo the garbage collector would kick in fairly quickly; after about 4 product screen views. I received messages that the activities, tasks, drawables, and tasks associated with the product screen were all purged from memory. This was also confirmed by my native heap gaining free space and not growing in overall size. The thunderbolt however never called the finalize methods on anything other than Tasks. This means that every activity was still being kept in memory along with WebViews and BitmapDrawables. Even though the references to all objects were deleted on the activity shutdown methods; the objects were never cleared from memory causing large memory usage.
Iím unable to recommend any fixes at this time. All Android best practices are being exercised in our app. We have concluded that all references are being deleted and all bitmaps have been recycled either by manually calling recycle or through the Bitmap object being finalized.