Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

A .NET Crash: How not to write a global exception handler

If broken it is, fix it you should — Mon, 06 Feb 2006 14:29:43 GMT

I’ve written quite a few posts on memory issues because that is the type of problem we get most frequently...

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

RichB — Tue, 07 Feb 2006 17:33:56 GMT

Note: .net v2 sos.dll can be found in %windir%\Microsoft.net\framework\v2....\sos.dll

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

The King — Wed, 08 Feb 2006 16:20:12 GMT

Use the following commands for loading SOS for the .net 2.0 framework...

.cordll -u -lp %windows%\Microsoft.NET\Framework\v2.0.50727\

.load %windows%\Microsoft.NET\Framework\v2.0.50727\sos

Hail to the king baby.

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Chakravarthy — Thu, 09 Mar 2006 15:34:38 GMT

Hello,

One of the .NET sites developed using 1.1 goes down now and then with a 'Service Unavailable' error - could it be a memory problem which can be debugged as above , or do you think it could be something else more specific ?

Regards.

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Tess — Thu, 09 Mar 2006 18:27:28 GMT

Service unavailable means that the process crashed and you will likely see a stopped unexpectedly event in the eventlog. Depending on if the memory usage is high or not you would debug it as a crash or a high mem issue. For crashes run adplus -crash -pn w3wp.exe to get a dump of the process when it crashes.

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Halindar — Sun, 26 Mar 2006 22:33:26 GMT

Hi Tess,

Our 1.1 ASP.NET application recently started to throw some 1000 events faulting mscorsvr.dll. I would like to start using the debug tools you described but since the faults only occur once in a few days and it is a production site I would like to know how much performance impact and security risk is attached to running debug tools like these in a production environment.

Ewoud

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Tess — Mon, 27 Mar 2006 08:15:12 GMT

Hi Ewoud,

The impact depends a little on how many exceptions you're throwing and what config files you use.

If you throw a lot of null reference exceptions and use the default (just -crash) you will get a minidump for each first chance exception which might stall the process a little. If so i would recommend running the debugger with

adplus -crash -pn <processname.exe> -NoDumpOnFirst

to begin with, and then monitor it for a little bit just to make sure it's not making a huge impact.

If your app is not throwing a lot of NullReferenceExceptions you should be good to go with just -crash.

We do use this in a production environment all the time though, that is what they are meant for, its just a matter of getting the right configuration for your environment.

Thanks

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Chakravarthy — Thu, 20 Apr 2006 20:21:11 GMT

I am trying to pick up the basics of production debugging by going through one of the documents on the Patterns and Practices site about the use of DBG. In the walkthrough, i created a System Monitor report in Performance tool, for .NET Clr memory object, for aspnet_wp. When i see the counters in report view, the #Bytes in all heaps shows 19,01456, whereas the Gen 0 Heap size is 83,88608, Gen 1 is 7,99968 , Gen 2 is 1,28592 and Gen 3 is 9,72896. So the Gen0 + Gen1 + Gen 2 + Large Objects do not add up to #Bytes in all heaps - in fact they are more.

I am using XP Professional and IIS 5.1 . Any idea on what could be wrong ?

Thanks.

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Tess — Fri, 21 Apr 2006 09:19:22 GMT

Hi Chakravarthy,

Are these numbers for average or maximum or last?

Also what do the commas in the numbers mean? and how many bytes do you have on the loader heap?

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Chakravarthy — Fri, 21 Apr 2006 11:19:43 GMT

Thanks for trying to help.

These numbers are last, because i just invoked the sample program called memory.aspx. which has buttons to load large blocks of memory and other buttons to release them, none of which i have clicked yet, and have just selected the system monitor parameters for aspnet_wp , to have the baseline numbers , like the walkthrough said. The commas are for the indian lakhs , which is one hundred thousand. Sorry, i should have presented the commas at million and thousand positions as below (these are my latest numbers in 'Performance', after loading but not running the memory.aspx) -

.NET CLR loading :-

Bytes in loader heap - 1,056,768

.NET Clr memory :-

#Bytes in all heaps - 1,796,856
#Gen 0 collection - 6
#Gen 1 collections - 2
#Gen 2 collections - 1
% Time in GC - 0.021
Gen 0 Heap size - 8,061,040
Gen 1 Heap size - 642,028
Gen 2 Heap size - 173,740
large Object Heap size - 981,088

The walthrough had said the '#Bytes in all heaps' would add upto Gen 0, 1,2 and Large Object heap size. So i am just trying to get that baseline right.

Just point me in the right direction and i will resume the walkthrough anyway - i just wanted to get the basics.

Thanks again.

Chak.

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Tess — Fri, 21 Apr 2006 12:06:28 GMT

I agree, this looks very odd... it is completely omitting the Gen 0 heap size

#Bytes in all heaps - 1,796,856
=
Gen 1 Heap size - 642,028
Gen 2 Heap size - 173,740
large Object Heap size - 981,088

I had never noticed this before because the Gen 0 size is negligable in most cases (compared to the others) and I had never explicitly added up the numbers but this seems to be true when i tested it on my machine as well...

Since this seemed weird it prompted me to do some investigation and the problem is not the #Bytes in all heaps, but rather the perception of what the Gen 0 counter tells us. (Btw, i was under the wrong impression about this as well:))

Reading from http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/gngrfmemoryperformancecounters.asp

Gen 0 heap size: "Displays the maximum bytes that can be allocated in generation 0; it does not indicate the current number of bytes allocated in generation 0."

However... the Gen 1 heap size and Gen 2 heap size counters are different... for example Gen 1

"Displays the current number of bytes in generation 1; this counter does not display the maximum size of generation 1. Objects are not directly allocated in this generation; they are promoted from previous generation 0 garbage collections. This counter is updated at the end of a garbage collection, not at each allocation."

Having said this... What you see in "#Bytes in all heaps" is very close to current reality, so do trust it...

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Allen — Thu, 22 Jun 2006 22:05:52 GMT

You mentioned doing a crash dump by breaking on Kernel32!ExitProcess. I need to do this or an ASP.NET worker process. Can you provide the adplus command line to do this.

Something like:

adplus -crash -pn aspnet_wp.exe ...?

thanks!

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Allen — Thu, 22 Jun 2006 23:59:05 GMT

Nevermind that request..I came across the config file from John Robbins that does the trick...



<ADPlus>
<Settings>

<RunMode>
CRASH
</RunMode>

<Option>
Quiet
</Option>
</Settings>
<Exceptions>

<Option>
NoDumpOnFirstChance
</Option>
</Exceptions>
<Breakpoints>
<NewBP>

<Address>
kernel32!ExitProcess
</Address>

<Type>
BP
</Type>


<Actions>
FullDump;
Stacks
</Actions>


<ReturnAction>
G
</ReturnAction>
</NewBP>
</Breakpoints>
</ADPlus>

Brian Low » CLR Debugging

Brian Low » CLR Debugging — Sat, 20 Jan 2007 00:46:53 GMT

PingBack from http://www.brianlow.com/index.php/2007/01/19/clr-debugging/

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Keith — Wed, 24 Jan 2007 01:49:22 GMT

If you are experiencing Memory Dumps where your system crashes and show you the blue screen of death, I suggest you go to

http://www.barrett.net/xpmemorydump.html

print off the 5 instruction pages and then work through them. You should then have cured the problem

ASP.Net Quick Tips - Caching

Ancora Imparo — Wed, 07 Mar 2007 16:02:49 GMT

This is part four in the ASP.Net tips series . In particular, this is a follow-up to, " ASP.Net Quick

A .NET Crash: How not to write a global exception handler

If broken it is, fix it you should — Mon, 20 Aug 2007 15:53:03 GMT

I’ve written quite a few posts on memory issues because that is the type of problem we get most frequently

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Richard Hayden — Sat, 25 Aug 2007 10:26:35 GMT

I have a question? I had a memory dump going into pogo games. I'm using w2kpro. my computer went to the blue screen and said that is was dumping physical memory. Do I have cause for alarm?

re: Back to Basics - How do I get the memory dumps in the first place? And what is SOS.dll?

Alex — Mon, 10 Aug 2009 14:08:59 GMT

Thanks Tess! It helped me solve the problem!

Best regards, Alex (alex.besogonov@gmail.com)