Re: system hang debug - C# Discussion Boards

18-Jan-09 19:59

Hello everyone,

I met with a system hang issue (a program does not run to complete). It is a managed code program (C# console) and run on Windows Server 2003 x64. Are there any ideas or recommended documents about how to narrow down such hang problem?

thanks in advance,
George

N a v a n e e t h18-Jan-09 20:34

18-Jan-09 20:34

What that application is doing? Is that entering into some infinite loop?

Navaneeth

How to use google | Ask smart questions

George_George18-Jan-09 20:50

18-Jan-09 20:50

Thanks Navaneeth,

The application is dealing with sending data to a web services and retrieve results to analyze. Any general ideas to debug and analyze further for application hang problem?

regards,
George

N a v a n e e t h18-Jan-09 20:55

18-Jan-09 20:55

George_George wrote:
Any general ideas to debug and analyze further for application hang problem?

You can step into the code and check which line execution is hanging. Identify why it is hanging. If the method which is hanging provides a timeout mechanism, use that so that your code will timeout if it can't process within the limit and will not make the whole application hang.

Navaneeth

How to use google | Ask smart questions

George_George19-Jan-09 1:26

19-Jan-09 1:26

Thanks Navaneeth,

I found the root cause is a method is timeout. I posted my code in the below link. Do you have any ideas? I suspect there is a bug or leak in my code, but I am not 100% sure. Any ideas?

http://www.codeproject.com/script/Forums/View.aspx?fid=1649&msg=2885910[^]

regards,
George

Luc Pattyn18-Jan-09 21:21

18-Jan-09 21:21

Hi George,

1.
if only one app hangs, you shouldn't call it a system hang. You are not going to reboot are you?

2.
if the problem occurs consistently you might just perform normal debugging. if on the other hand the
hang is occasional, I would add tracing code, so the app reports its activities to a file, one line at a time, with the time prefixed. In fact I always do that, from the very beginning, long before it starts to go wrong; and I tend to use File.AppendText so the file is normally closed and can be read while the app is running.

Without trace logs, intermittent or occasional problems are hard to debug, while single-stepping and breakpointing, you are never sure the problem will occur...
With trace logs, you can focus on a bad run; or you can compare traces from a bad run with those from a good run.

Smile | :)

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N a v a n e e t h18-Jan-09 21:26

18-Jan-09 21:26

Luc Pattyn wrote:
Without trace logs, intermittent or occasional problems are hard to debug, while single-stepping and breakpointing, you are never sure the problem will occur...
With trace logs, you can focus on a bad run; or you can compare traces from a bad run with those from a good run.

That's a good suggestion

Smile | :)

Navaneeth

How to use google | Ask smart questions

George_George19-Jan-09 1:27

19-Jan-09 1:27

Agree, Navaneeth. Smile | :)

regards,
George

George_George19-Jan-09 1:28

19-Jan-09 1:28

Thanks Luc!

I found the root cause is a method is timeout. I posted my code in the below link. Do you have any ideas? I suspect there is a bug or leak in my code, but I am not 100% sure. Any ideas?

http://www.codeproject.com/script/Forums/View.aspx?fid=1649&msg=2885910[^]

regards,
George

Luc Pattyn19-Jan-09 1:53

19-Jan-09 1:53

I have lots of ideas, the first and most important ones are here already[^].

Smile | :)

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modified on Friday, June 10, 2011 12:14 PM

George_George19-Jan-09 2:05

19-Jan-09 2:05

Hi Luc,

I have read them and the timeout issue is found from your advice when I narrow down my code. I do not know why there is unexpected timeout. Any ideas?

regards,
George

Luc Pattyn19-Jan-09 2:14

19-Jan-09 2:14

George_George wrote:
the timeout issue is found

Please explain. And did it cause a code change?

George_George wrote:
Any ideas?

Lots of them.
Log everything with timing info, up to milliseconds.
Show us the logs.
Don't trust anything.
What are those servers? your code too? Make it log its actions too!
You're the guy trying to send huge files while the network traffic is low, aren't you?
Tell us the complete story, not just some snippets.
Experiment. Try longer timeouts.
Catch ALL exceptions, not just WebExceptions. Log them too.
etc. etc.

Summary: observe, add observation tools, observe more; think, formulate an hypothesis, validate
your hypothesis, use the gray cells.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

I use ListBoxes for line-oriented text output (not TextBoxes), and PictureBoxes for pictures (not drawings).

George_George19-Jan-09 2:27

19-Jan-09 2:27

Thanks Luc!

It is strange that when I change the address to external servers, like google.com and ask.com. The results are the same -- for the beginning couple of times, the connections are successful, but for the following connections, all timeout. Could you reproduce?

regards,
George

Luc Pattyn19-Jan-09 2:41

19-Jan-09 2:41

There is no need to reproduce, you just told everyone what the problem is.
How many files can one open on a PC?

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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modified on Friday, June 10, 2011 12:15 PM

George_George19-Jan-09 2:47

19-Jan-09 2:47

Thanks Luc,

1.

"How many files can one open on a PC?" -- is it related to my question?

2.

I find when I call close method on response, the problem is solved. Why? .Net does not release resource automatically?

regards,
George

Luc Pattyn19-Jan-09 2:53

19-Jan-09 2:53

George_George wrote:
is it related to my question?

was it part of my reply to your question?

George_George wrote:
.Net does not release resource automatically?

it does, in a lazy way. That is why we have Dispose() and Close() methods, so we can tell it to perform some cleanup sooner hence reducing the load of the app on system resources. When an object no longer needs to be open, you should call Close() if that exists. When an object is no longer needed, you should call Dispose() if that exists, and not touch it any more. That is Kyoto for programmers.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

I use ListBoxes for line-oriented text output (not TextBoxes), and PictureBoxes for pictures (not drawings).

modified on Friday, June 10, 2011 12:15 PM

George_George19-Jan-09 2:56

19-Jan-09 2:56

Thanks Luc!

1.

Why if I do not call close, there will be timeout? I can not think of the relationship between them. Smile | :)

2.

"was it part of my reply to your question?" -- confused. What do you want to express?

regards,
George

Luc Pattyn19-Jan-09 3:18

19-Jan-09 3:18

George_George wrote:
Why ... there will be timeout?

GetResponse needs some system resources to execute the request, those resources are finite, and since you have chosen not to release them explicitly, it has to wait for them and can not even start executing your command, possibly longer than the allotted time to perform its entire operation.

The way networking has been implemented there is only a limited number of concurrent operations supported; not closing some helps in hitting the ceiling pretty soon.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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modified on Friday, June 10, 2011 12:16 PM

George_George19-Jan-09 19:20

19-Jan-09 19:20

Thanks Luc,

"those resources are finite" -- should be open connection handles in my scenario?

My confusion is, what is the limitation number? Any documents mentions the number? I find it is too small, in my testing, less than 10. Smile | :)

regards,
George

Luc Pattyn19-Jan-09 21:24

How to use design pattern for calling multiple assemblies

19-Jan-09 21:24

George_George wrote:
open connection handles in my scenario?

amongst others. empty buffers in a protocol stack, whatever.

George_George wrote:
what is the limitation number?

I don't know, I never had a need to know. I close stuff in time.

George_George wrote:
Any documents mentions the number?

I don't know. Your search tools are as good as mine.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

I use ListBoxes for line-oriented text output (not TextBoxes), and PictureBoxes for pictures (not drawings).

modified on Friday, June 10, 2011 12:16 PM

mpavas18-Jan-09 19:12

mpavas

18-Jan-09 19:12

Hello,

I have a project which uses various different assmeblies for each task
for example:

Crop pdf - assembly
Write Word - assembly
Create excel and convert to HTML - assembly

Now there can be n number of assemblies which will be used based on some condition.

I have two questions as below:

What kind of pattern will be best suited for this?
How can I make sure that the code written by each individual for each assembly do not have a common code in place.

Regards,
Pavas

Re: How to use design pattern for calling multiple assemblies

N a v a n e e t h18-Jan-09 19:51