You've already forked linux-packaging-mono
152 lines
7.5 KiB
Plaintext
152 lines
7.5 KiB
Plaintext
The garbage collector looks at a number of environment variables which are
|
|
then used to affect its operation. These are examined only on Un*x-like
|
|
platforms and win32.
|
|
|
|
GC_INITIAL_HEAP_SIZE=<bytes> - Initial heap size in bytes. May speed up
|
|
process start-up.
|
|
|
|
GC_MAXIMUM_HEAP_SIZE=<bytes> - Maximum collected heap size.
|
|
|
|
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_DUMP_REGULARLY - Generate a GC debugging dump GC_dump() on startup
|
|
and during every collection. Very verbose. Useful
|
|
if you have a bug to report, but please include only the
|
|
last complete dump.
|
|
|
|
GC_BACKTRACES=<n> - Generate n random backtraces (for heap profiling) after
|
|
each GC. Collector must have been built with
|
|
KEEP_BACK_PTRS. This won't generate useful output unless
|
|
most objects in the heap were allocated through debug
|
|
allocators. This is intended to be only a statistical
|
|
sample; individual traces may be erroneous due to
|
|
concurrent heap mutation.
|
|
|
|
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,
|
|
since the lock implementation will immediately yield without
|
|
first spinning.
|
|
|
|
GC_MARKERS=<n> - Linux w/threads and parallel marker only. Set the number
|
|
of marker threads. This is normaly set to the number of
|
|
processors. It is safer to adjust GC_MARKERS than GC_NPROCS,
|
|
since GC_MARKERS has no impact on the lock implementation.
|
|
|
|
GC_NO_BLACKLIST_WARNING - Prevents the collector from issuing
|
|
warnings about allocations of very large blocks.
|
|
Deprecated. Use GC_LARGE_ALLOC_WARN_INTERVAL instead.
|
|
|
|
GC_LARGE_ALLOC_WARN_INTERVAL=<n> - Print every nth warning about very large
|
|
block allocations, starting with the nth one. Small values
|
|
of n are generally benign, in that a bounded number of
|
|
such warnings generally indicate at most a bounded leak.
|
|
For best results it should be set at 1 during testing.
|
|
Default is 5. Very large numbers effectively disable the
|
|
warning.
|
|
|
|
GC_IGNORE_GCJ_INFO - Ignore the type descriptors implicitly supplied by
|
|
GC_gcj_malloc and friends. This is useful for debugging
|
|
descriptor generation problems, and possibly for
|
|
temporarily working around such problems. It forces a
|
|
fully conservative scan of all heap objects except
|
|
those known to be pointerfree, and may thus have other
|
|
adverse effects.
|
|
|
|
GC_PRINT_BACK_HEIGHT - Print max length of chain through unreachable objects
|
|
ending in a reachable one. If this number remains
|
|
bounded, then the program is "GC robust". This ensures
|
|
that a fixed number of misidentified pointers can only
|
|
result in a bounded space leak. This currently only
|
|
works if debugging allocation is used throughout.
|
|
It increases GC space and time requirements appreciably.
|
|
This feature is still somewhat experimental, and requires
|
|
that the collector have been built with MAKE_BACK_GRAPH
|
|
defined. For details, see Boehm, "Bounding Space Usage
|
|
of Conservative Garbage Collectors", POPL 2001, or
|
|
http://lib.hpl.hp.com/techpubs/2001/HPL-2001-251.html .
|
|
|
|
GC_RETRY_SIGNALS, GC_NO_RETRY_SIGNALS - Try to compensate for lost
|
|
thread suspend signals in linux_threads.c. On by
|
|
default for GC_OSF1_THREADS, off otherwise. Note
|
|
that this does not work around a possible loss of
|
|
thread restart signals. This seems to be necessary for
|
|
some versions of Tru64. Since we've previously seen
|
|
similar issues on some other operating systems, it
|
|
was turned into a runtime flag to enable last-minute
|
|
work-arounds.
|
|
|
|
GC_IGNORE_FB[=<n>] - (Win32 only.) Try to avoid treating a mapped
|
|
frame buffer as part of the root set. Certain (higher end?)
|
|
graphics cards seems to result in the graphics memory mapped
|
|
into the user address space as writable memory.
|
|
Unfortunately, there seems to be no systematic way to
|
|
identify such memory. Setting the environment variable to n
|
|
causes the collector to ignore mappings longer than n MB.
|
|
The default value of n is currently 15. (This should cover
|
|
a 16 MB graphics card, since the mapping appears to be slightly
|
|
shorter than all of graphics memory. It will fail if a dll
|
|
writes pointers to collectable objects into a data segment
|
|
whose length is >= 15MB. Empirically that's rare, but
|
|
certainly possible.) WARNING: Security sensitive applications
|
|
should probably disable this feature by setting
|
|
GC_disallow_ignore_fb, or by building with -DNO_GETENV,
|
|
since small values could force collection of reachable
|
|
objects, which is conceivably a (difficult to exploit)
|
|
security hole. GC_IGNORE_FB values less than 3 MB
|
|
are never honored, eliminating this risk for most,
|
|
but not all, applications. This feature is likely to disappear
|
|
if/when we find a less disgusting "solution".
|
|
IN VERSION 6.4 AND LATER, THIS SHOULD BE UNNECESSARY.
|
|
|
|
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_ENABLE_INCREMENTAL - Turn on incremental collection at startup. Note that,
|
|
depending on platform and collector configuration, this
|
|
may involve write protecting pieces of the heap to
|
|
track modifications. These pieces may include pointerfree
|
|
objects or not. Although this is intended to be
|
|
transparent, it may cause unintended system call failures.
|
|
Use with caution.
|
|
|
|
GC_PAUSE_TIME_TARGET - Set the desired garbage collector pause time in msecs.
|
|
This only has an effect if incremental collection is
|
|
enabled. If a collection requires appreciably more time
|
|
than this, the client will be restarted, and the collector
|
|
will need to do additional work to compensate. The
|
|
special value "999999" indicates that pause time is
|
|
unlimited, and the incremental collector will behave
|
|
completely like a simple generational collector. If
|
|
the collector is configured for parallel marking, and
|
|
run on a multiprocessor, incremental collection should
|
|
only be used with unlimited pause time.
|
|
|
|
GC_FIND_LEAK - Turns on GC_find_leak and thus leak detection. Forces a
|
|
collection at program termination to detect leaks that would
|
|
otherwise occur after the last GC.
|
|
|
|
GC_ALL_INTERIOR_POINTERS - Turns on GC_all_interior_pointers and thus interior
|
|
pointer recognition.
|
|
|
|
GC_DONT_GC - Turns off garbage collection. Use cautiously.
|