Question

I have an application that works with large amounts of data, and I’m thinking that, may be, sometimes the OutOfMemoryException will be thrown (For half a year, I got no single exception, but I’m just want to know all about it). As I’ve investigated, after this exception I can’t proceed with execution of my program.

Is there any good pattern to handle such exceptions, especially to working with IDisposable classes?

Answer 1

In a genuine OOM scenario (more likely on x86 than x64) you are pretty doomed there. Almost anything would cause an allocation, so your best option is to die as quickly and elegantly as possible, doing minimum harm.

Since it isn’t happening, don’t stress overly, but avoidance is better than handling here:

• use streaming data APIs rather than buffering everything in memory
• re-use buffers etc
• avoid enormous arrays/lists/etc (in truth, the most likely way to cause an OOM is to request an enormous (but single) array) – for example, a jagged array scales better than a 2D array (even on x64 there is a hard limit on the maximum size of a single array)
• think about how you handle sparse data
• do you read lots of strings from external sources? If so, consider around a custom interner so you don’t have 20,000 different copies of common strings (country names, for example)
• keep an eye on what you release when
• avoid accidentally prolonged life on objects, especially via event subscriptions (notorious for accidental extensions to lifetimes)