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Here are some tips about getting/controlling the memory usage of a given process…

Current memory usage
You can use GetProcessMemoryInfo() API function to get the current memory usage (in bytes), peak usage, number of bytes in pagefile currently used by a process, and so on. Add Windows to your uses clause and use something like this :

procedure ShowMemUsage(PID:Cardinal);
var
    memCounters:_PROCESS_MEMORY_COUNTERS;
    h:cardinal;
begin
    ZeroMemory(@memCounters,sizeof(memCounters));
    h:=OpenProcess(PROCESS_QUERY_INFORMATION or PROCESS_VM_READ, false, PID);
    if h<>0 then begin
        memCounters.cb := sizeof(memCounters);
        if not GetProcessMemoryInfo(h, @memCounters, sizeof(memCounters)) then
            showmessage('Coulnd''t get memory info!')
        else
            showmessage('Current : '+inttostr(memCounters.WorkingSetSize shr 10)+' K'#13#10+'Peak : '+inttostr(memCounters.PeakWorkingSetSize shr 10 )+' K'#13#10+'Pagefile : '+inttostr(memCounters.PageFaultCount shr 10)+' K');
        closehandle(h);
    end;
end;

Memory limits
GetProcessWorkingSetSize() will give you the minimum and maximum amount of physical memory that may be used by a process. SetProcessWorkingSetSize() allows you to set new limits. Note that Windows OS treats these values as a “friendly suggestion”, so there is no guarantee they will be adhered to.

Get the minimum/maximum limits (in bytes) :

h,mMin,mMax:cardinal;
{...}
h:=OpenProcess(PROCESS_QUERY_INFORMATION or PROCESS_VM_READ, false, PID);
GetProcessWorkingSetSize(h,mMin,mMax);
CloseHandle(h);

Set limits :

h,newMin,newMax:cardinal;
{...}
h:=OpenProcess(PROCESS_QUERY_INFORMATION or PROCESS_SET_QUOTA, false, PID);
SetProcessWorkingSetSize(h, newMin, newMax);

You can also send a process to the cache (swap it out of memory) by calling SetProcessWorkingSetSize(h, $FFFFFFFF, $FFFFFFFF) , though that will only give a temporary effect and the process will be swapped back if it is actively working on some task.

Many so-called “memory managers” and “optimizers” rely on these functions to “defragment” memory, etc – when a process is sent to cache, only active and neccessary parts are swapped back to RAM, so its memory usage becomes somewhat optimized. Working set sizes can theoretically be manipulated to achieve better memory subsystem perfomance, but that would require intimate knowledge of how Windows manages RAM and memory management in general. So I’m currently rather sceptical about aforementioned utilities.

I hope this info will be useful to you 🙂