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My application seems to hang. What do I do? – Part 2

Last time I talked about the hang scenario where your process is taking 0 CPU and the CPU is taking by other process(es) on the same machine.   The next scenario is your process is taking 0 CPU and the CPU is barely used by other processes.   As one of the readers correctly pointed out, this is very likely because you have a ...

Correlating the output of !eeheap -gc and !address

!address is a very powerful debugger command. It shows you exactly what your VM space looks like. If you already got the output from the !sos.eeheap -gc command (refer to this article for usage on sos), for example: 0:003> !eeheap -gcNumber of GC Heaps: 1generation 0 starts at 0x01245078generation 1 starts at 0x0124100cgeneration 2 starts ...

New MSDN Article – Investigating Memory Issues

We have a new MSDN article out in the November issue that talks about investigating managed memory issues. http://msdn.microsoft.com/msdnmag/issues/06/11/CLRInsideOut/default.aspx?loc=en Take a look and let me know what you think. Oh, and it's also in 6 other languages (German, Spanish, French, Russian, Portuguese and Chinese) ...

My application seems to hang. What do I do? – Part 1

Defining “hang” is a good place to start.   When people say “hang” they could mean all sorts of things. When I say “hang” I mean the process is not making progress – the threads in the process are either blocked (eg. deadlocked, or not scheduled because of threads from other processes) or executing code (madly) but not doing...

Understand the problem before you try to find a solution

So far I’ve never written a blog entry that gives out philosophical advices on doing performance work. But lately I thought perhaps it’s time to write such an entry because I’ve seen enough people who looked really hard at some performance counters (often not correct ones) or some other data and asked tons of questions such as “is this...

I Am a Happy Janitor – Part 1: Finding garbage

Indeed what I do is very much like the job of the janitors – like the ones who clean your building, or janitors you see at a food court, or yourself when you are taking care of garbage at your house. Doubtful you say? Let me prove it to you. Finding garbage What do you do when you are having lunch with your friends at a food court and ...

Suspending and resuming threads for GC

First of all, suspension and resumption of threads is not really part of the GC. GC calls functions to do the suspension and the resumption as a service provided in the CLR. Other components in the CLR also use this service such as the debugger implementation. But it’s true that suspending and resuming because of the GC is the most ...

When memory is running low…

When I say memory I mean physical memory. Let’s assume that you have enough virtual memory space. When the physical memory gets low you may start getting OOMs or start paging. You can experiment and see how you can avoid getting into the low memory situation but sometimes it’s hard to predict and hard to test all scenarios your app can get...

Large Object Heap

LOH (Large Object Heap) contains objects that are 85,000 bytes or bigger (there’s also some objects that are less than 85,000 bytes that are allocated on the LOH by the runtime itself but usually they are very small and we’ll ignore them for this discussion).   The way LOH is implemented changed dramatically from 1.0 to 1.1. In 1.0 ...

Workstation GC for server applications?

In Using GC Efficiently – Part 2 I talked about different flavors of GC that exist in the CLR and how you choose which flavor is good for your applications, and I said that the Server GC flavor is designed for server applications. As with any performance tuning there are always exceptions – there’s no one-rule-fits-all. Recently I worked...