[Vm-dev] Re: [Pharo-project] Memory problems on Windows

Andreas Raab andreas.raab at gmx.de
Sat Sep 4 19:28:43 UTC 2010

There is indeed a hard limit of 512MB in the Windows VM currently in 
effect, which is the result of debugging some extremely strange effects 
when loading DLLs. What we found was that on some systems, under some 
circumstances (related to memory load etc) DLLs would not be loaded if 
we'd reserve more than 512MB of memory leading the application either to 
not start at all, or to cause weird effects at later points etc.

   - Andreas

On 9/4/2010 2:14 AM, Mariano Martinez Peck wrote:
> You can also ask in VM mailing list. I cc'ed them.
> On Sat, Sep 4, 2010 at 4:52 AM, Jimmie Houchin <jlhouchin at gmail.com
> <mailto:jlhouchin at gmail.com>> wrote:
>     Hello,
>     Sorry for the delay in reply. For some reason the first time I
>     looked at your message in my newsreader (Thunderbird/GMane) the
>     message was in French and written to someone else. Apparently the
>     software did something strange.
>     To answer your question. Yes. I tried this in both the standard vm
>     and the standard Pharo 1.1 image.
>     I start the vm/image with -memory: 1000
>     and open a new Workspace, then copy the below memory settings and doit.
>     I then do  a := Array new: 100000000.
>     That seemingly succeeds but only takes me up to a little below 500mb
>     ram. If I attempt to do another array of another 100,000,000
>     objects, I get the Low Space error.
>     With the standard vm and image, it just sits there consuming cpu
>     with simply doing the array initialization. I am on a quad core
>     server with 6gm ram and it has currently consumed over 36 cpu
>     minutes of one of the cores. At this point I quit the image. I could
>     do things in the UI but it is not very responsive.
>     In the Cog vm/image, the array creation returns almost immediately
>     and waits for other instructions.
>     As I write this I have to go back to Squeak 3.7.1vm and either the
>     3.8 or 3.10 image, for it to be successful. Outside of that I can't
>     get past 500mb of ram. This server generally sits at only using 30%
>     of ram.
>     For enterprise/business endeavors, I thing Pharo really needs to be
>     able to use all the memory the OS will allow it. I know that it
>     being a 32 bit app does create some limits on some OSes. But neither
>     of my Vista machines imposes a limit that I can't live with at the
>     moment.
>     Thanks for your reply. I am neither a vm nor Smalltalk expert so I
>     don't know how to proceed from here outside of reducing my
>     applications memory needs by putting more into the database and only
>     having the data in memory that is absolutely necessary for the
>     analysis I am attempting.
>     Jimmie
>     On 9/1/2010 4:48 AM, Stéphane Ducasse wrote:
>         do you have the same problem with the normal VM?
>         On Sep 1, 2010, at 5:25 AM, Jimmie Houchin wrote:
>             Hello,
>             I am developing an application which processes and generates
>             a large amount of data. In a recent attempt I encountered an
>             Space is Low error.
>             This is occurring in a Pharo 1.1 image using the latest
>             Pharo and Cog VMs. I am opening the vm with the -memory:
>             1000 parameter.
>             The below code I have applied the from the Squeak list from
>             the 100 Million Objects thread. But the problem occurs at
>             about 500mb of ram on a computer with 3 (or 6) gb of ram,
>             with only 65% of physical ram in use. The os is Vista.
>             Any help in using more memory, as much as necessary for the
>             app, would be greatly appreciated.
>             initializeMemorySettings
>             "Initialize the memory and GC settings to be more in line
>             with QF requirements"
>             "The following settings affect the rate incremental GCs and
>             tenuring"
>             "Limit incremental GC activity to run every 40k allocations"
>               SmalltalkImage current vmParameterAt: 5 put: 40000.
>             "allocations between GCs (default: 4000)"
>             "Limit tenuring threshold to only tenure w/>  10k survivors"
>               SmalltalkImage current vmParameterAt: 6 put: 10000.
>             "tenuring threshold (default: 2000)"
>             "These settings affect overall memory usage"
>             "Only give memory back to the OS when we have more than 16MB
>             free"
>               SmalltalkImage current vmParameterAt: 24 put:
>             16*1024*1024. "default 8MB"
>             "Try to keep 8MB headroom at all times"
>               SmalltalkImage current vmParameterAt: 25 put: 8*1024*1024.
>             "default 4MB"
>             "These settings describe what to do when we're close to
>             running out of free space"
>             "Tell the VM that we'd rather grow than spinning in tight GC
>             loops"
>               SmalltalkImage current gcBiasToGrow: true. "default: false"
>             "Tell the VM to do a fullGC for good measure if the above
>             growth exceeded 16MB"
>               SmalltalkImage current gcBiasToGrowLimit: 16*1024*1024.
>             "default: 0"
>             Thanks,
>             Jimmie Houchin
>             _______________________________________________
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