ChangeLog

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:

    https://github.com/jemalloc/jemalloc

* 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)

* 4.3.0 (November 4, 2016)

  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
    4.2.0.  (@vsarunas, @jasone)
  - 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
    allocation.  (@kspinka, @Whissi, @jasone)
  - 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)

* 4.2.0 (May 12, 2016)

  New features:
  - Add the arena.<i>.reset mallctl, which makes it possible to discard all of
    an arena's allocations in a single operation.  (@jasone)
  - 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)

* 4.1.0 (February 28, 2016)

  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
    specify --with-malloc-conf=purge:decay , since the default must remain
    purge:ratio until the 5.0.0 release.  (@jasone)
  - Add MS Visual Studio 2015 support.  (@rustyx, @yuslepukhin)
  - Make *allocx() size class overflow behavior defined.  The maximum
    size class is now less than PTRDIFF_MAX to protect applications against
    numerical overflow, and all allocation functions are guaranteed to indicate
    errors rather than potentially crashing if the request size exceeds the
    maximum size class.  (@jasone)
  - jeprof:
    + Add raw heap profile support.  (@jasone)
    + Add --retain and --exclude for backtrace symbol filtering.  (@jasone)

  Optimizations:
  - Optimize the fast path to combine various bootstrapping and configuration
    checks and execute more streamlined code in the common case.  (@interwq)
  - Use linear scan for small bitmaps (used for small object tracking).  In
    addition to speeding up bitmap operations on 64-bit systems, this reduces
    allocator metadata overhead by approximately 0.2%.  (@djwatson)
  - Separate arena_avail trees, which substantially speeds up run tree
    operations.  (@djwatson)
  - Use memoization (boot-time-computed table) for run quantization.  Separate
    arena_avail trees reduced the importance of this optimization.  (@jasone)
  - Attempt mmap-based in-place huge reallocation.  This can dramatically speed
    up incremental huge reallocation.  (@jasone)

  Incompatible changes:
  - Make opt.narenas unsigned rather than size_t.  (@jasone)

  Bug fixes:
  - Fix stats.cactive accounting regression.  (@rustyx, @jasone)
  - Handle unaligned keys in hash().  This caused problems for some ARM systems.
    (@jasone, @cferris1000)
  - Refactor arenas array.  In addition to fixing a fork-related deadlock, this
    makes arena lookups faster and simpler.  (@jasone)
  - Move retained memory allocation out of the default chunk allocation