[Mono-dev] [Mono-gc-list] Mono memory problems!

Miguel de Icaza miguel at novell.com
Wed Jul 18 12:06:02 EDT 2007


> namespace Ipop {
>   public class IPOP_Common {
>     public static void Main() {
>       AutoResetEvent re = null;
>       while(true) {
>         re = new AutoResetEvent(false);
>         re.Close();
>       }
>     }
>   }
> }
> 
> blows up memory

That depends on the finalizer to run to release memory from the
unmanaged side, since AutoResetEvent implements IDisposable you should
use it like this:

	using (re = AutoResetEvent (false)) {	
		...

Miguel
> whereas ...
> 
> using System.Security.Cryptography;
> using System;
> 
> namespace Ipop {
>   public class IPOP_Common {
>     public static void Main() {
>       RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
>       while(true) {
>         byte[] key = new byte[1024];
>         rng.GetBytes(key);
>       }
>     }
>   }
> }
> 
> This doesn't.
> 
> David Wolinsky wrote:
> > We run this software on system where memory is a concern.  The data that 
> > we presented is our test case system that has 50 nodes all running in 
> > the same mono process.  We run only a single node at each site which 
> > initially starts at ~15 MB, we've seen it swell to well over 300 MBs in 
> > a period of less than a week.  Since this must be used in production 
> > environments and is meant to be extremely lightweight we can forgive a 
> > small memory portion like 15 MB, since it has relatively no processing 
> > overhead, but at over 300 MBs our processes are often stopped by the 
> > remote admin and we are told to clean up the problem.
> >
> > Since this seems to be a problem of using a non-compacting gc, do you 
> > know where the compacting gc is, so that we could at least test it out.  
> > I searched the SVN and found no clues of it.
> >
> > Also, I should correct myself, the results for memory consumption were 
> > not directly related to the test that grows at 25kB/sec.  I found this 
> > out after posting the data, I am running heap-shot right now with the 
> > correct test and it has grown 100MB in less than 1 hour.
> >
> > Regards,
> > David
> >
> >
> >
> > Alan McGovern wrote:
> >   
> >> Well, after 12 hours at a consistent 25kB/sec, you'd expect to have 
> >> over 1 gig of memory allocated. As you don't, i think what you're 
> >> seeing is just 'normal usage' for the non-compacting GC that mono 
> >> uses. I have a similar app which uses sockets extensively (50-150 
> >> simultaneous connections)  and i can assure you that memory usage 
> >> doesn't get unbearably large. It'd be interesting to see the logs but 
> >> i don't think there's much to be worried about.
> >>
> >> Alan.
> >>
> >> On 7/18/07, *David Wolinsky* <davidiw at ufl.edu 
> >> <mailto:davidiw at ufl.edu>> wrote:
> >>
> >>     Initially 45 MB, 12 hours later 147 MB
> >>
> >>     Another developer has the heap-shot logs, I'll post those as soon as
> >>     possible.
> >>
> >>     David
> >>
> >>     Alan McGovern wrote:
> >>     > Could you post up the detailed stats from heapshot? After the 12
> >>     hour
> >>     > run, how much memory are you using? Are we talking in the gigabyte
> >>     > range, or megabyte range?
> >>     >
> >>     > Alan.
> >>     >
> >>     > On 7/18/07, *David Wolinsky* <davidiw at ufl.edu
> >>     <mailto:davidiw at ufl.edu>
> >>     > <mailto:davidiw at ufl.edu <mailto:davidiw at ufl.edu>>> wrote:
> >>     >
> >>     >     My lab works on a peer-to-peer network overlay and we've noticed
> >>     >     recently significant memory issues.  Some background...
> >>     >
> >>     >     This application is constantly creating new objects and shortly
> >>     >     thereafter deleting (removing reference to) them
> >>     >     Using a sample run with 150 threads running...
> >>     >     Mono on Linux has a growth rate of ~25 KB per second with a
> >>     base
> >>     >     of 50MB
> >>     >     (y = 25K *x + 50M)
> >>     >     .NET on Windows stabilizes at 35 MB
> >>     >
> >>     >     We ran heap-shot with Linux and found that in a 12 hour
> >>     period it
> >>     >     reported this...
> >>     >     start:
> >>     >     objects: 58,823
> >>     >     heap memory: 6,838,426 bytes
> >>     >
> >>     >     end:
> >>     >     objects: 59,925
> >>     >     heap memory: 6,862,336
> >>     >
> >>     >     We have run mono with GC_MAXIMUM_HEAP_SIZE and the memory size
> >>     >     (RES) got
> >>     >     significantly bigger than it.
> >>     >
> >>     >     I have searched for the Compacting GC with no luck, we would
> >>     >     really like
> >>     >     to see if it would help our problem.
> >>     >
> >>     >     The only operating system resources we're using are Sockets, but
> >>     >     we use
> >>     >     them VERY heavily!
> >>     >
> >>     >     If anyone has any suggestions, we'd be open to test out
> >>     anything
> >>     >     at this
> >>     >     point!
> >>     >
> >>     >     We are leaning towards an issue in unmanaged memory and
> >>     possibly a bug
> >>     >     in mono.
> >>     >
> >>     >     Best regards,
> >>     >     David
> >>     >
> >>     >
> >>     >     ps, I fwded this to gc and devel list because gc list looks
> >>     quite
> >>     >     dead.... sorry for the duplication
> >>     >     _______________________________________________
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> >>     >
> >>     >
> >>
> >>
> >>     
> >
> > _______________________________________________
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> >
> >   
> 
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