Re: Garbage Collection - Strange Results.
- From: "CodeGuru" <CodeGuru@xxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 18 May 2005 13:48:06 -0700
Willy,
Thanks for the info, now that you mention it, and reviewing your posting
for a second time, I noticed something you mentioned !! that could
possibly .. maybe be a serious problem !
you said "I am holding onto buffers in my read / write" when infact
and indeed I am.. I have created a private member for each socket
that has a Buffer for reading and a ObjectBuffer for completing.
once a full object has been completed I copy it to a completed buffer
and execute a Reflection on it to "create" the actual object from
the serialization stream (socket) more over, the object buffer never
really gets destroyed unless the socket is killed.. so perhaps your
telling me that because I have these infact may be the pinned objects?
in my application ?
Also: pinned object in performance monitor shows drastic values;
it goes anywhere between 0 to 2000 pinned objects on each update.
Private Bytes in Process shows over 300 MB for Active 500 Sockets...
and 50 threads.
Kaz
"Willy Denoyette [MVP]" wrote:
>
> "CodeGuru" <CodeGuru@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:602B1F08-9484-420C-B157-2652E54E046B@xxxxxxxxxxxxxxxx
> > Althought I have read hundreds if not more pages on
> > msdn as well other sites on IDisposable and heap
> > generations. I am still a bit confused as to why
> > the application I have written is acting in such
> > "weird/awkward" manner.
> >
> > Basic outline of the application goes:
> >
> > Multi threaded socket application using Asynchronous
> > writes/reads/connects via TCP Sockets.
> >
> > I have written an application that starts 100 threads
> > and attaches 10 sockets from a peer to each of these
> > threads; thus 1000 active sockets open.
> >
> > Now. the application runs fine; I calculate using ANTS profiler
> > or any other profiling utility and it tells me that I have approximately
> > 30 MB of Memory used.
> >
> > I call GC.GetTotalMemory(false) or even (true) and it gives me
> > approximately
> > the same values depending what stage of processing each thread
> > is at.
> >
> > All threads are doing the same thing by the way.
> >
> > When I look in Windows Performance Monitor and under .NET Memory
> > for that particular application the memory seems to be quite high.
> >
> > Several Hundred MEGABYTES.
> >
> > The application runs over time.. slowly but surely increasing in memory.
> > as the threads complete their tasks with the sockets it closes them.
> > and Disposes each and every object. I explicitly set each object to null
> > as well its children.. and have inherited IDisposable on almost all
> > objects.
> >
> > What I don't understand is why the memory keeps increasing,
> > while the application keeps reporting only 30MB of usage... the memory
> > keeps increasing and increasing until the system runs out of Physical
> > Memory
> > and causes OutOfMemoryExpections.... its quite strange. I am not doing
> > anything within the application that would create anything larger then it
> > should.
> >
> > However I do thousands of XmlSerializations using a single MemoryStream
> > for each socket that is created; there are thousands of Asychronous
> > callbacks
> > that are happening.
> >
> > My Generation 0 and 1 heaps seem to be doing just fine.. but 2nd gen heap
> > seems to be at hundreds of megs; its very strange to see this.
> >
> > I assumed that the .NET GC will keep on expanding the space required until
> > it is ready for a garbage collection.. would it be because of the
> > magnitute of
> > ArrayLists that I am using ? or perhaps there are scattered memory
> > segments.
> > throughout the Heaps ? is the GC having a difficult time collecting all
> > the
> > resources?
> >
> > Any help on why this is occuring would be appreciated.
> >
> > I have tried my best to clean up all the resources.. but I figure that
> > most of the objects created should automatically get cleaned up
> > after it is out of the final scope that it is passed to.. for example.
> > once a command comes in via the Async Read Callback, I process it
> > and pass it to the appropriate thread DataReceive method.
> > I not only dispose the object within CallBack but I also dispose
> > the reference that was passed again just incase..
> >
> > doesn't seem to be doing anything .. and what is even more strange
> > is why is .NET or all Profilers such as ANTS .NET profiler report
> > that I am only using 30MB of memory ? when in Task Manager
> > or Performance Monitor I see hundreds of megs like 600+.
> >
> > Thank you and great weekend to all.
>
> 1. Don't use taskman, use perfmon and the "CLR Memory" counters Gen0, 1 and
> 2 size to watch managed memory consumption.
> 2. Take a look at the # of pinned objects using perfmon (CLR memory
> counters).
> 3. Use perfmon to watch your "process" privates bytes.
>
> If the the Gen 2 counter indicates a steady growth and the number of pinned
> objects is rather high (> 100) chances are that pinned objects are aging
> into Gen2 and as such preventing compactation of the heap.
> If that's the case you are probably holding references to socket
> (read/write) buffers for the lifetime of the socket.
>
> I would also suggest you to reduce the number of threads, 100 threads is
> only a waste of resources (both memory and CPU) when using asynchronous
> sockets.
>
> Willy.
>
>
>
>
>
.
- References:
- Garbage Collection - Strange Results.
- From: CodeGuru
- Re: Garbage Collection - Strange Results.
- From: Willy Denoyette [MVP]
- Garbage Collection - Strange Results.
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