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Following are change highlights associated with official releases. Important
bug fixes are all mentioned, but some internal enhancements are omitted here for
brevity. Much more detail can be found in the git revision history:
* 4.5.0 (February 28, 2017)
This is the first release to benefit from much broader continuous integration
testing, thanks to @davidtgoldblatt. Had we had this testing infrastructure
in place for prior releases, it would have caught all of the most serious
regressions fixed by this release.
New features:
- Add --disable-thp and the opt.thp mallctl to provide opt-out mechanisms for
transparent huge page integration. (@jasone)
- Update zone allocator integration to work with macOS 10.12. (@glandium)
- Restructure *CFLAGS configuration, so that CFLAGS behaves typically, and
EXTRA_CFLAGS provides a way to specify e.g. -Werror during building, but not
during configuration. (@jasone, @ronawho)
Bug fixes:
- Fix DSS (sbrk(2)-based) allocation. This regression was first released in
4.3.0. (@jasone)
- Handle race in per size class utilization computation. This functionality
was first released in 4.0.0. (@interwq)
- Fix lock order reversal during gdump. (@jasone)
- Fix/refactor tcache synchronization. This regression was first released in
4.0.0. (@jasone)
- Fix various JSON-formatted malloc_stats_print() bugs. This functionality
was first released in 4.3.0. (@jasone)
- Fix huge-aligned allocation. This regression was first released in 4.4.0.
(@jasone)
- When transparent huge page integration is enabled, detect what state pages
start in according to the kernel's current operating mode, and only convert
arena chunks to non-huge during purging if that is not their initial state.
This functionality was first released in 4.4.0. (@jasone)
- Fix lg_chunk clamping for the --enable-cache-oblivious --disable-fill case.
This regression was first released in 4.0.0. (@jasone, @428desmo)
- Properly detect sparc64 when building for Linux. (@glaubitz)
* 4.4.0 (December 3, 2016)
New features:
- Add configure support for *-*-linux-android. (@cferris1000, @jasone)
- Add the --disable-syscall configure option, for use on systems that place
security-motivated limitations on syscall(2). (@jasone)
- Add support for Debian GNU/kFreeBSD. (@thesam)
Optimizations:
- Add extent serial numbers and use them where appropriate as a sort key that
is higher priority than address, so that the allocation policy prefers older
extents. This tends to improve locality (decrease fragmentation) when
memory grows downward. (@jasone)
- Refactor madvise(2) configuration so that MADV_FREE is detected and utilized
on Linux 4.5 and newer. (@jasone)
- Mark partially purged arena chunks as non-huge-page. This improves
interaction with Linux's transparent huge page functionality. (@jasone)
Bug fixes:
- Fix size class computations for edge conditions involving extremely large
allocations. This regression was first released in 4.0.0. (@jasone,
@ingvarha)
- Remove overly restrictive assertions related to the cactive statistic. This
regression was first released in 4.1.0. (@jasone)
- Implement a more reliable detection scheme for os_unfair_lock on macOS.
(@jszakmeister)
* 4.3.1 (November 7, 2016)
Bug fixes:
- Fix a severe virtual memory leak. This regression was first released in
4.3.0. (@interwq, @jasone)
- Refactor atomic and prng APIs to restore support for 32-bit platforms that
use pre-C11 toolchains, e.g. FreeBSD's mips. (@jasone)
This is the first release that passes the test suite for multiple Windows
configurations, thanks in large part to @glandium setting up continuous
integration via AppVeyor (and Travis CI for Linux and OS X).
New features:
- Add "J" (JSON) support to malloc_stats_print(). (@jasone)
- Add Cray compiler support. (@ronawho)
Optimizations:
- Add/use adaptive spinning for bootstrapping and radix tree node
initialization. (@jasone)
Bug fixes:
- Fix large allocation to search starting in the optimal size class heap,
which can substantially reduce virtual memory churn and fragmentation. This
regression was first released in 4.0.0. (@mjp41, @jasone)
- Fix stats.arenas.<i>.nthreads accounting. (@interwq)
- Fix and simplify decay-based purging. (@jasone)
- Make DSS (sbrk(2)-related) operations lockless, which resolves potential
deadlocks during thread exit. (@jasone)
- Fix over-sized allocation of radix tree leaf nodes. (@mjp41, @ogaun,
@jasone)
- Fix over-sized allocation of arena_t (plus associated stats) data
structures. (@jasone, @interwq)
- Fix EXTRA_CFLAGS to not affect configuration. (@jasone)
- Fix a Valgrind integration bug. (@ronawho)
- Disallow 0x5a junk filling when running in Valgrind. (@jasone)
- Fix a file descriptor leak on Linux. This regression was first released in
- Fix static linking of jemalloc with glibc. (@djwatson)
- Use syscall(2) rather than {open,read,close}(2) during boot on Linux. This
works around other libraries' system call wrappers performing reentrant
- Fix OS X default zone replacement to work with OS X 10.12. (@glandium,
@jasone)
- Fix cached memory management to avoid needless commit/decommit operations
during purging, which resolves permanent virtual memory map fragmentation
issues on Windows. (@mjp41, @jasone)
- Fix TSD fetches to avoid (recursive) allocation. This is relevant to
non-TLS and Windows configurations. (@jasone)
- Fix malloc_conf overriding to work on Windows. (@jasone)
- Forcibly disable lazy-lock on Windows (was forcibly *enabled*). (@jasone)
* 4.2.1 (June 8, 2016)
Bug fixes:
- Fix bootstrapping issues for configurations that require allocation during
tsd initialization (e.g. --disable-tls). (@cferris1000, @jasone)
- Fix gettimeofday() version of nstime_update(). (@ronawho)
- Fix Valgrind regressions in calloc() and chunk_alloc_wrapper(). (@ronawho)
- Fix potential VM map fragmentation regression. (@jasone)
- Fix opt_zero-triggered in-place huge reallocation zeroing. (@jasone)
- Fix heap profiling context leaks in reallocation edge cases. (@jasone)
New features:
- Add the arena.<i>.reset mallctl, which makes it possible to discard all of
- Add the stats.retained and stats.arenas.<i>.retained statistics. (@jasone)
- Add the --with-version configure option. (@jasone)
- Support --with-lg-page values larger than actual page size. (@jasone)
Optimizations:
- Use pairing heaps rather than red-black trees for various hot data
structures. (@djwatson, @jasone)
- Streamline fast paths of rtree operations. (@jasone)
- Optimize the fast paths of calloc() and [m,d,sd]allocx(). (@jasone)
- Decommit unused virtual memory if the OS does not overcommit. (@jasone)
- Specify MAP_NORESERVE on Linux if [heuristic] overcommit is active, in order
to avoid unfortunate interactions during fork(2). (@jasone)
Bug fixes:
- Fix chunk accounting related to triggering gdump profiles. (@jasone)
- Link against librt for clock_gettime(2) if glibc < 2.17. (@jasone)
- Scale leak report summary according to sampling probability. (@jasone)
* 4.1.1 (May 3, 2016)
This bugfix release resolves a variety of mostly minor issues, though the
bitmap fix is critical for 64-bit Windows.
Bug fixes:
- Fix the linear scan version of bitmap_sfu() to shift by the proper amount
even when sizeof(long) is not the same as sizeof(void *), as on 64-bit
Windows. (@jasone)
- Fix hashing functions to avoid unaligned memory accesses (and resulting
crashes). This is relevant at least to some ARM-based platforms.
(@rkmisra)
- Fix fork()-related lock rank ordering reversals. These reversals were
unlikely to cause deadlocks in practice except when heap profiling was
enabled and active. (@jasone)
- Fix various chunk leaks in OOM code paths. (@jasone)
- Fix malloc_stats_print() to print opt.narenas correctly. (@jasone)
- Fix MSVC-specific build/test issues. (@rustyx, @yuslepukhin)
- Fix a variety of test failures that were due to test fragility rather than
core bugs. (@jasone)
This release is primarily about optimizations, but it also incorporates a lot
of portability-motivated refactoring and enhancements. Many people worked on
this release, to an extent that even with the omission here of minor changes
(see git revision history), and of the people who reported and diagnosed
issues, so much of the work was contributed that starting with this release,
changes are annotated with author credits to help reflect the collaborative
effort involved.
New features:
- Implement decay-based unused dirty page purging, a major optimization with
mallctl API impact. This is an alternative to the existing ratio-based
unused dirty page purging, and is intended to eventually become the sole
purging mechanism. New mallctls:
+ opt.purge
+ opt.decay_time
+ arena.<i>.decay
+ arena.<i>.decay_time
+ arenas.decay_time
+ stats.arenas.<i>.decay_time
(@jasone, @cevans87)
- Add --with-malloc-conf, which makes it possible to embed a default
options string during configuration. This was motivated by the desire to
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