maoni, Author at .NET Blog

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GC Handles

February 6th, 2020

A customer asked me about analyzing perf related to GC handles. I feel like aside from pinned handles in general handles are not talked about much so this topic warrants some explanation, especially since this is a user facing feature. For some background info, GC handles are indeed generational so when we are doing ephemeral GCs we only need...

GC Perf Infrastructure – Part 1

December 9th, 2019

We open sourced our new GC Perf Infrastructure! It’s now part of the dotnet performance repo. I’ve been meaning to write about it ‘cause some curious minds had been asking when they could use it after I blogged about it last time but didn’t get around to it till now. First of all, let me point out that the target audience of this ...

The history of the GC configs

November 2nd, 2019

Recently, Nick from Stack Overflow tweeted about his experience of using the .NET Core GC configs – he seemed quite happy with them (minus the fact they are not documented well which is something I’m talking to our doc folks about). I thought it’d be fun to tell you about the history of the GC configs ‘cause it’s almost the weekend ...

Finalization implementation details

September 16th, 2019

Years ago I wrote a document on making finalization scanning concurrent. At the time there was an internal team that was using finalization as a way to resurrect objects and putting them back in their cache. While we’ve always advised to folks that finalization was for releasing native resources I couldn’t fault this team for using it the ...

GC Perf Infrastructure – Part 0

September 9th, 2019

In this blog entry and some future ones I will be showing off functionalities that our new GC perf infrastructure provides. Andy and I have been working on it (he did all the work; I merely played the consultant role). We will be open sourcing it soon and I wanted to give you some examples of using it and you can add these to your repertoire ...

A portable way to get GC events in process and no admin privilege with 10 lines of code (and ability to dynamically enable/disable events)

April 8th, 2019

I’ve been talking about doing managed heap performance analysis with ETW events for ages because ETW is just such a powerful tool. It has a well defined format so many components, from kernel modes to user mode ones, all emit ETW events which means you can have tools that just know how to parse the event format and correlate them. At ...

Making CPU configuration better for GC on machines with > 64 CPUs

April 3rd, 2019

If you are running Windows on a machine with > 64 CPUs, you’ll need to use this feature called the CPU groups for your process to be able to use more than 64 CPUs. At some point in the far distant past, people thought having more than 64 processors on a machine was inconceivable so they used a 64-bit number for the processor mask. And when ...

Running with Server GC in a Small Container Scenario Part 1 – Hard Limit for the GC Heap

February 4th, 2019

I’ve checked in 2 configs related to specifying a hard limit for the GC heap memory usage so I wanted to describe them and how they are intended to be used. Feedback would be greatly appreciated. In order to talk about the new configs it’s important to understand what consists of the memory usage in a process. When it comes to memory the ...

Running with Server GC in a Small Container Scenario Part 0

November 16th, 2018

This week I was able to get some time to work on the container stuff with low memory limits. As many of you have expressed your dissatisfaction on how Server GC behaves with low memory limit specified on containers on github, I have to apologize that I am just doing this now. Really sorry that some of you guys have to suffer through this thus ...

You Should Never See This Callstack in Production

October 9th, 2018

A customer who just experienced some server outage asked us for help as they thought it was due to some very long GC pauses. I thought this diagnostics exercise might be useful for other folks as well so I am sharing it with you. We had them collect a GCCollectOnly trace which showed there were some very long induced gen2 blocking GCs. And ...

Maoni Stephens

.NET GC Architect, .NET Runtime Team