What is the Solution?

When you have verified the application actually is suffering from the mis-, ab- or overuse of either weak, soft or phantom references, the solution often involves changing the application’s intrinsic logic. This is very application specific and generic guidelines are thus hard to offer. However, some generic solutions to bear in mind are:

  • Weak references – if the problem is triggered by increased consumption of a specific memory pool, an increase in the corresponding pool (and possibly the total heap along with it) can help you out. As seen in the example section, increasing the total heap and young generation sizes alleviated the pain.
  • Phantom references – make sure you are actually clearing the references. It is easy to dismiss certain corner cases and have the clearing thread to not being able to keep up with the pace the queue is filled or to stop clearing the queue altogether, putting a lot of pressure to GC and creating a risk of ending up with an OutOfMemoryError.
  • Soft references – when soft references are identified as the source of the problem, the only real way to alleviate the pressure is to change the application’s intrinsic logic.