Large amount of garbage with deep dependency tree

[ReneZwanenburg]

Our ASP application has a few deeply nested dependency hierarchies, with the size of a tree in the order of thousands of objects. When resolving such a dependency, Autofac 3.5.2 generates a lot of garbage: loading a representative webpage results in ~ 50 MB worth of allocations coming from Autofac, less than one percent of the allocated bytes are for the resulting instances. The top allocations are ConcatIterators and various lambda's. It's not leaking, everything gets cleaned up nicely at the next GC cycle, but the high amount of allocations puts pressure on the GC and causes our heaps to be significantly larger than necessary.

There might be some improvements possible. I haven't looked at Autofac's code close enough to say for certain, but these kinds of changes often involve replacing linq and lambdas with something a bit less nice-looking around the heaviest allocating places. If you're potentially open to changes of this nature I'm willing to work on this.

[alexmg]

We are definitely open to such improvements. I would work with the develop branch that has the current 4.0 RC version if you would like to look further into the issue.

[alexmg]

I've pushed Autofac 4.3.0 to NuGet and look forward to taking this for a spin at the office tomorrow.

[nblumhardt]

@ReneZwanenburg any chance you can try out the 4.3.0 build and let us know if it's improved matters? Cheers!

[tillig]

I'm going to close this with the caveat that if folks see specific ways to improve, we're totally open to that. PRs for optimizations [ideally without breaking API changes] are always welcome.