[RkWard-devel] handling of loaded packages?

[Thomas Friedrichsmeier]

On Saturday 06 January 2007 01:47, SJR wrote:
> while fiddling around with some packages I was wondering how to handle
> loaded packages. The usual way is require(). Then the package is loaded and
> kept in the workspace.
> This is also happening in some of the coming new plug-ins e.g. the
> distribution analysis, though very limited. Since RKWard will also handle
> very sophisticated tasks in future we will require more packages that do
> not belong to the basics (base, stats, graphics, ...). Should we pay
> attention to workspace "cleaning procedures".  For example if package YX is
> not required for, let's say 10 minutes, then package XY is unloaded else
> kept for the next time frame and so on. Maybe it's "wise" to keep memory
> usage as low as possible, though I did a little test and there is only
> little change when some pages are loaded. Loading of packages will be fast
> anyway. But I don't see a way to do it automatically in R.

Some thoughts:
1) The 10 minutes feature would be nice, but somehow we'd need to figure out, 
when a package is used. Of course, we could check, when it is require ()d, 
but this would not be enough, since the user may well be using the package, 
without calling require each time. Also, libraries, which depend on other 
libraries, typically call require () only when loading, but not necessarily 
in every function. So I'm afraid, I can see no good way of doing this. If 
anybody has some more insight on this, I'm eager to learn about it.

2) Memory testing is not trivial with R, due to R's strategy of memory 
handling. IIRC it's something like this:
Allocate memory up to 32MB. When 32MB is hit, try to throw unused object away. 
Hence typically, memory usage will increase until 32MB is hit, then stay 
there for a long time, regardless of what you do. If 32MB is not enough to 
accomodate all active symbols, another chunk of memory is allocated. This or 
something along those lines.

3) *Probably* it's not quite as important an issue, as the packages are only 
loaded, if / when the user actually uses the corresponding functions. 
Typically a user will only use so many plugins per session, so not it's 
unlikely that very many libraries will be loaded. A new session will start 
out fresh.

Well, I think it hinges on 1). If we can find a satisfactory solution to that, 
we can attack the issue. Else we'll have to hope 3 always applies...

Regards
Thomas
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