This is a broader application of optimizations to malloc() and free() in
f4a0f32d (Fast-path improvement:
reduce # of branches and unnecessary operations.).

This resolves #321.

If the OS overcommits:
- Commit all mappings in pages_map() regardless of whether the caller
  requested committed memory.
- Linux-specific: Specify MAP_NORESERVE to avoid
  unfortunate interactions with heuristic overcommit mode during
  fork(2).

This resolves #193.

This makes the numbers reported in the leak report summary closely match
those reported by jeprof.

This resolves #356.

This resolves #367.

Link libjemalloc against librt if clock_gettime(2) is in librt rather
than libc, as for versions of glibc prior to 2.17.

This resolves #349.

Split arena_choose() into arena_[i]choose() and use arena_ichoose() for
arena lookup during internal allocation.  This fixes huge_palloc() so
that it always succeeds during extent node allocation.

This regression was introduced by
66cd9535 (Do not allocate metadata via
non-auto arenas, nor tcaches.).

Depending on virtual memory resource limits, it is necessary to attempt
allocating three maximally sized objects to trigger OOM rather than just
two, since the maximum supported size is slightly less than half the
total virtual memory address space.

This fixes a test failure that was introduced by
0c516a00 (Make *allocx() size class
overflow behavior defined.).

This resolves #379.

Fix witness to clear its list of owned mutexes in the child if
platform-specific malloc_mutex code re-initializes mutexes rather than
unlocking them.

This assures that side effects of internal allocation don't impact
tests.

Reset large curruns to 0 during arena reset.

Do not increase huge ndalloc stats during arena reset.

This regression was caused by 66cd9535
(Do not allocate metadata via non-auto arenas, nor tcaches.).

This resolves #375.

This makes it possible to discard all of an arena's allocations in a
single operation.

This resolves #146.

This assures that all internally allocated metadata come from the
first opt_narenas arenas, i.e. the automatically multiplexed arenas.

Change test-related mangling to simplify symbol filtering.

The following commands can be used to detect missing/obsolete symbol
mangling, with the caveat that the full set of symbols is based on the
union of symbols generated by all configurations, some of which are
platform-specific:

./autogen.sh --enable-debug --enable-prof --enable-lazy-lock
make all tests
nm -a lib/libjemalloc.a src/*.jet.o \
  |grep " [TDBCR] " \
  |awk '{print $3}' \
  |sed -e 's/^\(je_\|jet_\(n_\)\?\)\([a-zA-Z0-9_]*\)/\3/g' \
  |LC_COLLATE=C sort -u \
  |grep -v \
   -e '^\(malloc\|calloc\|posix_memalign\|aligned_alloc\|realloc\|free\)$' \
   -e '^\(m\|r\|x\|s\|d\|sd\|n\)allocx$' \
   -e '^mallctl\(\|nametomib\|bymib\)$' \
   -e '^malloc_\(stats_print\|usable_size\|message\)$' \
   -e '^\(memalign\|valloc\)$' \
   -e '^__\(malloc\|memalign\|realloc\|free\)_hook$' \
   -e '^pthread_create$' \
  > /tmp/private_symbols.txt

Add 4 missing symbols

Also remove tautological cassert(config_debug) calls.

This fixes a compilation error caused by
b2c0d632 (Add witness, a simple online
locking validator.).

This resolves #375.

Fix a compilation error that occurs if Valgrind is not enabled.  This
regression was caused by b2c0d632 (Add
witness, a simple online locking validator.).

This resolves #358.

This regression was caused by 8f683b94
(Make opt_narenas unsigned rather than size_t.).

Use 1U rather than ZU(1) in macro definitions, so that the preprocessor
can evaluate the resulting expressions.

During over-allocation in preparation for creating aligned mappings,
allocate one more page than necessary if PAGE is the actual page size,
so that trimming still succeeds even if the system returns a mapping
that has less than PAGE alignment.  This allows compiling with e.g. 64
KiB "pages" on systems that actually use 4 KiB pages.

Note that for e.g. --with-lg-page=21, it is also necessary to increase
the chunk size (e.g. --with-malloc-conf=lg_chunk:22) so that there are
at least two "pages" per chunk.  In practice this isn't a particularly
compelling configuration because so much (unusable) virtual memory is
dedicated to chunk headers.

Consistently use uint8_t rather than char for junk filling code.

Refactor ph to support configurable comparison functions.  Use a cpp
macro code generation form equivalent to the rb macros so that pairing
heaps can be used for both run heaps and chunk heaps.

Remove per node parent pointers, and instead use leftmost siblings' prev
pointers to track parents.

Fix multi-pass sibling merging to iterate over intermediate results
using a FIFO, rather than a LIFO.  Use this fixed sibling merging
implementation for both merge phases of the auxiliary twopass algorithm
(first merging the aux list, then replacing the root with its merged
children).  This fixes both degenerate merge behavior and the potential
for deep recursion.

This regression was introduced by
6bafa667 (Pairing heap).

This resolves #371.