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

David Wolinsky davidiw at ufl.edu
Wed Jul 18 11:20:08 EDT 2007


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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