The garbage collector looks at a number of environment variables which are the used to affect its operation. These are examined only on Un*x-like platforms.
GC_INITIAL_HEAP_SIZE=<bytes> - Initial heap size in bytes. May speed up
process start-up.
GC_LOOP_ON_ABORT - Causes the collector abort routine to enter a tight loop.
This may make it easier to debug, such a process, especially
for multithreaded platforms that don't produce usable core
files, or if a core file would be too large. On some
platforms, this also causes SIGSEGV to be caught and
result in an infinite loop in a handler, allowing
similar debugging techniques.
GC_PRINT_STATS - Turn on as much logging as is easily feasible without
adding signifcant runtime overhead. Doesn't work if
the collector is built with SMALL_CONFIG. Overridden
by setting GC_quiet. On by default if the collector
was built without -DSILENT.
GC_PRINT_ADDRESS_MAP - Linux only. Dump /proc/self/maps, i.e. various address
maps for the process, to stderr on every GC. Useful for
mapping root addresses to source for deciphering leak
reports.
GC_NPROCS=<n> - Linux w/threads only. Explicitly sets the number of processors
that the GC should expect to use. Note that setting this to 1
when multiple processors are available will preserve
correctness, but may lead to really horrible performance.
GC_NO_BLACKLIST_WARNING - Prevents the collector from issuing
"Needed to allocate blacklisted block at ..." warnings.
The following turn on runtime flags that are also program settable. Checked only during initialization. We expect that they will usually be set through other means, but this may help with debugging and testing:
GC_FIND_LEAK - Turns on GC_find_leak and thus leak detection.
GC_ALL_INTERIOR_POINTERS - Turns on GC_all_interior_pointers and thus interior
pointer recognition.
GC_DONT_GC - Turns off garbage collection. Use cautiously.