Maximum Number of Open Windows under Windows?

Triones asks: "I have found that Windows 2000 has a limit on the number of distinct windows that can be opened. W2K cannot open more than around 70 distinct windows (duplicate IE's on the same url don't count) even when it has 50Mb free phyiscal memory and much more in system cache. The max I can get is about 75 windows. Similar limits on machines with 256Mb or 512Mb ram. Some of my friends have reproduced this phenomenon on their systems. (By the way, no such problem with Linux (Redhat, XFree86, Gnome, Sawfish)). Is it related to the graphics 'resource' (GDI?) in Windows? Is there a parameter that can be tuned to increase the limit? If this is a 'flaw', is it fixed in XP?"

Comments

Resource limitations

[man_ls]

IE uses about 10 MB of "memory" (swap or physical) per instance. You're right that duplicate URIs don't count; it probably has something to do about it is just displaying the same instance twice, not actually spawning a new one.

Office 2000 apps require in the range of 40MB of free memory. SCSIFiberPro 32 uses about 2MB. Winamp, Morpheus, etc. use 5-10 each.

That's not that much, however. What's really draining your memory is probably the services you're running.

LSASS uses only 1MB, so thats not a big deal, but SVCHOST uses 8-10, services.exe uses 10-ish, most of the others are in the 5-10 range, but there's about a dozen of them. With nothing running except for the services, I use 90MB of physical memory; it's about 105 when using IEXPLORE on top of that.

Windows doesn't have the best resource mangment available. However, Win 2K has considerably better than Windows 9x does - you'd crash long before you opened 70 some windows in one of those OSes.

(All numbers taken from the processes tab of Task Manager.)

JKoebel

Re:90 for me

[sigwinch]

Also, on linux, I was under the impression that the virtual terminals *were* limited - when you compile a kernel the default is 256 ptys; I may just be utterly wrong here, but I thought that meant there was a 256 virtual terminal limit.

True, although 256 ptys is probably more than enough for any single-user system. If you need more you can build a kernel that supports (IIRC) 2048 ptys.

I would presume it also applies to X - but does X open all of it's stuff in a single console terminal?

Ptys look like a serial port to the downstream process, but upstream is another process instead of serial port hardware. Thus they're only used for things like terminal emulators that really need serial port compatibility. Most X programs don't use them.

Is 70 windows really a limitation?

[serutan]

Maybe I'm missing the point, but would even a hard-coded max of 70 actually limit anyone's use of Windows in any meaningful sense?

An example of how this limitation would affect anybody would be interesting.