| gc {base} | R Documentation |
A call of gc causes a garbage collection to take place.
gcinfo sets a flag so that
automatic collection is either silent (verbose=FALSE) or
prints memory usage statistics (verbose=TRUE).
gc(verbose = getOption("verbose"), reset=FALSE)
gcinfo(verbose)
verbose |
logical; if TRUE, the garbage collection prints
statistics about cons cells and the space allocated for vectors. |
reset |
logical; if TRUE the values for maximum space used
are reset to the current values. |
A call of gc causes a garbage collection to take place.
This will also take place automatically without user intervention, and the
primary purpose of calling gc is for the report on memory usage.
However, it can be useful to call gc after a large object
has been removed, as this may prompt R to return memory to the
operating system.
R allocates space for vectors in multiples of 8 bytes: hence the
report of "Vcells", a relict of an earlier allocator (that used
a vector heap).
gc returns a matrix with rows "Ncells" (cons
cells), usually 28 bytes each on 32-bit systems and 56 bytes on
64-bit systems, and "Vcells" (vector cells, 8 bytes
each), and columns "used" and "gc trigger",
each also interpreted in megabytes (rounded up to the next 0.1Mb).
If maxima have been set for either "Ncells" or "Vcells",
a fifth column is printed giving the current limits in Mb (with
NA denoting no limit).
The final two columns show the maximum space used since the last call
to gc(reset=TRUE) (or since R started).
gcinfo returns the previous value of the flag.
Memory on R's memory management,
and gctorture if you are an R hacker.
reg.finalizer for actions to happen at garbage
collection.
gc() #- do it now gcinfo(TRUE) #-- in the future, show when R does it x <- integer(100000); for(i in 1:18) x <- c(x,i) gcinfo(verbose = FALSE)#-- don't show it anymore gc(TRUE) gc(reset=TRUE)