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digitalmars.D - GC and cleaning out Windows system resources

reply Stewart Gordon <smjg_1998 yahoo.com> writes:
Those who've been following SDWF'll know that it uses destructors and 
hence GC to free GDI resources.  However, there doesn't seem to be a way 
of making the GC automagically run when Windows gets low on resources.

I've started to try creating the object, and if it fails, running GC and 
then trying again.  But this leaves freeing resources to the last 
minute, which can cause other apps or even the whole system to crash in 
the meantime.

There therefore ought to be a way of catching a shortage of system 
resources before it gets to zero, in order to try GCing and freeing them 
up.  I haven't been able to find a Win32 function in Win9x that 
interrogates the levels of free resources, but obviously there's a way 
of doing it as Resource Meter and the System Properties section of 
Control Panel do.

That aside, one possibility I can see is to fit GC passes into the 
message loop.  Collecting on processing every message would be a bit 
inefficient, but I can see a possibility.  Maybe count the messages 
despatched, and after every (say) 100, do a genCollect.  Moreover, 
pauses could be absorbed by waiting till 100 messages have gone through 
_and_ the message queue is empty (using PeekMessage), then doing GC.

Does anyone have a better idea?

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on 
the 'group where everyone may benefit.
Sep 13 2004
parent reply Nigel Sandever <nigelsandever btconnect.com> writes:
On Mon, 13 Sep 2004 16:37:35 +0100, Stewart Gordon <smjg_1998 yahoo.com> wrote:

 Those who've been following SDWF'll know that it uses destructors and 
 hence GC to free GDI resources.  However, there doesn't seem to be a way 
 of making the GC automagically run when Windows gets low on resources.
 
 I've started to try creating the object, and if it fails, running GC and 
 then trying again.  But this leaves freeing resources to the last 
 minute, which can cause other apps or even the whole system to crash in 
 the meantime.
 
 There therefore ought to be a way of catching a shortage of system 
 resources before it gets to zero, in order to try GCing and freeing them 
 up.  I haven't been able to find a Win32 function in Win9x that 
 interrogates the levels of free resources, but obviously there's a way 
 of doing it as Resource Meter and the System Properties section of 
 Control Panel do.


There is a performace data counter that may help:

	260: Objects
	The Object performance object consists of counters that monitor  logical 
	objects in the system, such as processes, threads, mutexes, and 
	semaphores.  This information can be used to detect the unnecessary 
	consumption of computer resources.  Each object requires memory to store 
	basic information about the object.
	
This is accessed through the (psuedo-) registry key HKEY_PERFORMANCE_DATA (see 
WinPerf.h for details. 

Whether this is available for 95/98/ME I'm unsure.



 
 That aside, one possibility I can see is to fit GC passes into the 
 message loop.  Collecting on processing every message would be a bit 
 inefficient, but I can see a possibility.  Maybe count the messages 
 despatched, and after every (say) 100, do a genCollect.  Moreover, 
 pauses could be absorbed by waiting till 100 messages have gone through 
 _and_ the message queue is empty (using PeekMessage), then doing GC.
 
 Does anyone have a better idea?
 
 Stewart.
 
 -- 
 My e-mail is valid but not my primary mailbox.  Please keep replies on 
 the 'group where everyone may benefit.
Sep 13 2004
parent Stewart Gordon <smjg_1998 yahoo.com> writes:
Nigel Sandever wrote:
<snip>

 This is accessed through the (psuedo-) registry key HKEY_PERFORMANCE_DATA (see 
 WinPerf.h for details. 
 
 Whether this is available for 95/98/ME I'm unsure.


Alas, Win98 doesn't have it.  I noticed that it has HKEY_DYN_DATA, but 
that has nothing of relevance to be seen.

Does anyone have any idea why M$ deleted GetFreeSystemResources and 
provided no replacement?

Maybe this'll help though....

http://tinyurl.com/3o2z5

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on 
the 'group where everyone may benefit.
Sep 17 2004