Ayende @ Rahien

Alex Simkin commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 22:23:52 GMT

Oh, sorry, didn't read carefully enough. That's exactly what was asked.

Alex Simkin commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 22:21:18 GMT

@Duarte Could you please explain the solution. BufferPoolWithLeakDetection throws when system tries to garbage collect MemoryLeakException because buffer was already garbage collected. But if buffer was already garbage collected, where is the memory leak? No, it wasn't returned to the pool, but that's not what was asked.

Ayende Rahien commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 17:41:52 GMT

Duarte, Nice, and similar to how I decided to do this.

Duarte Nunes commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 12:44:46 GMT

Here's the code: [https://gist.github.com/948237](https://gist.github.com/948237)

Duarte Nunes commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 11:51:49 GMT

Maybe you could have a ConditionalWeakTable, where T is a type that defines a finalizer and has a StackTrace. If you throw an exception on the finalizer thread, the process dies. When a buffer is returned to the pool, you remove it from the table.

Nathan Evans commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 10:32:01 GMT

In that case, I look forward to seeing the solution.

Ayende Rahien commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 10:24:50 GMT

This means that you now have to track IBufferContext, rather than just byte[] There are better ways to do this.

Nathan Evans commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 10:20:05 GMT

Something like this is what I had in mind: [http://pastebin.com/ULNYap6u](http://pastebin.com/ULNYap6u) Obviously you'd use using {} blocks, where appropriate, when dealing with the IBufferContext's.

Linkgoron commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:55:08 GMT

Paul if I remember correctly you'd still be tied to the GC. According to the docs using a ConditionalWeakTable and maybe another list with the keys would be better.

Ayende Rahien commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:51:48 GMT

Nathan, Show me the code.

Ayende Rahien commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:51:15 GMT

Paul, That makes it a pretty complex system, and you are doing a lot that you probably shouldn't. There is also the issue of concurrent updates of timer & buffer takes/ returns.

Ayende Rahien commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:50:01 GMT

Paul, We are writing one right now.

Nathan Evans commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:49:49 GMT

Forgot to say, the StackTrace can be captured in the constructor (wrapped in #IF DEBUG of course) and stored in a private field. Then when the finalizer is called, maybe use Environment.FailFast to print a nice message with that stack trace info.

Nathan Evans commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:41:24 GMT

Standard IDisposable pattern (with finalizer hook) and some #IF DEBUG conditional blocks. The only uncertainty would be relying upon a GC to occur in order for the finalizer to be run. But your tests can simulate that.

Paul Stovell commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:39:42 GMT

That was a List> - you need a better blog engine :)

Paul Stovell commented on Challenge: Stop the leaks

Fri, 29 Apr 2011 09:38:38 GMT

Inside your implementation, have a List >. In TakeBuffer, wrap the list you return in a weak reference, and store the stack trace. In ReturnBuffer, remove it from the list. Have a timer (or another trigger) and periodically go through the list. If any of the WeakReferences have a null target, the buffer has been leaked. >