The allocations described as User-Controlled are not part of the GC-managed heap. The ones described as Transient happen to be but that is not user visible; alternate implementations might insure that they are freed as soon as the appropriate context is left.
If you are interested in managing the lifetime of heap-allocated objects then you register roots for the GC with R_PreserveObject. luke On Fri, 31 Mar 2006, Prof Brian Ripley wrote: > On Thu, 30 Mar 2006, Jeff Henrikson wrote: > >> r-help, > > [Moved to R-devel.] > >> The R manual lists two types of memory: transient and user-controlled. >> If I have transient blocks reachable from the globals only by traversal >> through user-controlled blocks, will they be correctly preserved? > > I don't understand your terminology, especially 'traversal'. It is not > normal to have either type of block reachable through R objects, and if > you are using something like external pointers, the answer would be no. > >> Secondly, what are the ways to mark user controlled blocks as "roots" >> for the garbage collector, so that transient blocks they reference stay >> uncollected? So far I can only deduce that as long as the answer to my >> first question is yes, I can bind an arbitrary symbol to them in the >> global environment. Is this the best way? > > I think you are referring to blocks allocated by R_alloc. The manual says > > This memory is taken from the heap, and released at the end of the .C, > .Call or .External call. Users can also manage it, by noting the current > position with a call to vmaxget and clearing memory allocated > subsequently by a call to vmaxset. This is only recommended for experts. > > If you want to allocate storage as part of an R object, this is not the > best way to do it (allocVector etc are). It is a side-effect of the > current implementation that memory allocated by R_alloc which is made part > of an object will be protected for the lifetime of that object, but this > is not documented and should not be relied on. (I am thinking if for > example a block is made into a CHARSXP 'by hand', but the documented route > is mkChar which makes a copy.) > >> Jeff Henrikson >> >> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > Please do, including the question `which list': this clearly belongs on > R-devel. > > -- Luke Tierney Chair, Statistics and Actuarial Science Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: [EMAIL PROTECTED] Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
