gctorture Torture Garbage Collector

Description

Provokes garbage collection on (nearly) every memory allocation. Intended to ferret out memory protection bugs. Also makes R run very slowly, unfortunately.

Usage

gctorture(on = TRUE)
gctorture2(step, wait = step, inhibit_release = FALSE)

Arguments

on	logical; turning it on/off.
step	integer; run GC every step allocations; step = 0 turns the GC torture off.
wait	integer; number of allocations to wait before starting GC torture.
inhibit_release	logical; do not release free objects for re-use: use with caution.

Details

Calling gctorture(TRUE) instructs the memory manager to force a full GC on every allocation. gctorture2 provides a more refined interface that allows the start of the GC torture to be deferred and also gives the option of running a GC only every step allocations.

The third argument to gctorture2 is only used if R has been configured with a strict write barrier enabled. When this is the case all garbage collections are full collections, and the memory manager marks free nodes and enables checks in many situations that signal an error when a free node is used. This can help greatly in isolating unprotected values in C code. It does not detect the case where a node becomes free and is reallocated. The inhibit_release argument can be used to prevent such reallocation. This will cause memory to grow and should be used with caution and in conjunction with operating system facilities to monitor and limit process memory use.

gctorture2 can also be invoked via environment variables at the start of the R session. R_GCTORTURE corresponds to the step argument, R_GCTORTURE_WAIT to wait, and R_GCTORTURE_INHIBIT_RELEASE to inhibit_release.

Value

Previous value of first argument.

Author(s)

Peter Dalgaard and Luke Tierney