Re: Garbage Collection - Strange Results.

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance


"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.




.

Relevant Pages

  • Garbage Collection - Strange Results.
    ... msdn as well other sites on IDisposable and heap ... writes/reads/connects via TCP Sockets. ... When I look in Windows Performance Monitor and under .NET Memory ... is why is .NET or all Profilers such as ANTS .NET profiler report ...
    (microsoft.public.dotnet.framework.clr)
  • Re: how to wait for socket communications
    ... the JVM when the Java program gets closed, and ending up with memory leaks. ... Unfortunately, in connection with getting advised not to use sockets, my ... in this context as memory allocation technique, not file I/O. ...
    (microsoft.public.win32.programmer.networks)
  • Re: PowerPC or PARISC?
    ... Don't forget that with Opteron even *local* memory accesses require ... the number of sockets. ... If you had bothered to look at the context in which Rob made the statement to which I replied, you would have found that it was that of snoop *responses* from CPUs. ...
    (comp.arch)
  • Re: PowerPC or PARISC?
    ... Don't forget that with Opteron even *local* memory accesses require ... the number of sockets. ... number of CPU cores. ...
    (comp.arch)
  • Re: OT: Rant
    ... posted by Paul J Gans ... every second or third boot threw memory errors. ... Eventually I concluded that I had a motherboard with a bad data ... I was then told that I must NEVER plug equipment into the wall sockets ...
    (talk.origins)