500 error - out-of-memory exception

Giganews Newsgroups
Subject: 500 error - out-of-memory exception
Posted by:  Griff (griffithsj_5…@hotmail.com)
Date: Tue, 7 Jul 2009

We have an IIS server that successfully runs a classic ASP web site
for many days and then all of a sudden the every ASP page responds
with a 500 error message.

Looking through the web logs, we find out of memory exceptions.

However, gone through all the code and it's not obvious where there
could be a memory leak....

Anyhow, decided to monitor the memory usage at the point of iis
dying.  There is a Window's API function GetProcessMemoryInfo which
returns the process' memory usage.

I logged the WorkingSetSize, PeakWorkingSetSize, PageFileUsage and
PeakPageFileUsage.

Most of the time whilst the server was healthy, I got the following
example values (all in MB):
PageFileUsage = 880
WorkingSetSize = 882
PeakPageFileUsage = 917
PeakWorkingSetSize = 918

So, these are all quite high values, but the server is a Win2000
server with 4GB of RAM (so IIS should have about 2GB to play with if I
understand this correctly).

However, at the time of the crash I got the following values:
PageFileUsage = 842
WorkingSetSize = 747
PeakPageFileUsage = 899
PeakWorkingSetSize = 904

So....at the time IIS fell over, the PageFileUsage  was GREATER than
the WorkingSetSize.  Not sure how this can be....

Any explanation would be most welcome.

Thanks in advance

Griff

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