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

* 5.1.0 (May 4th, 2018)

  This release is primarily about fine-tuning, ranging from several new features
  to numerous notable performance and portability enhancements.  The release and
  prior dev versions have been running in multiple large scale applications for
  months, and the cumulative improvements are substantial in many cases.

  Given the long and successful production runs, this release is likely a good
  candidate for applications to upgrade, from both jemalloc 5.0 and before.  For
  performance-critical applications, the newly added TUNING.md provides
  guidelines on jemalloc tuning.

  New features:
  - Implement transparent huge page support for internal metadata.  (@interwq)
  - Add opt.thp to allow enabling / disabling transparent huge pages for all
    mappings.  (@interwq)
  - Add maximum background thread count option.  (@djwatson)
  - Allow prof_active to control opt.lg_prof_interval and prof.gdump.
    (@interwq)
  - Allow arena index lookup based on allocation addresses via mallctl.
    (@lionkov)
  - Allow disabling initial-exec TLS model.  (@davidtgoldblatt, @KenMacD)
  - Add opt.lg_extent_max_active_fit to set the max ratio between the size of
    the active extent selected (to split off from) and the size of the requested
    allocation.  (@interwq, @davidtgoldblatt)
  - Add retain_grow_limit to set the max size when growing virtual address
    space.  (@interwq)
  - Add mallctl interfaces:
    + arena.<i>.retain_grow_limit  (@interwq)
    + arenas.lookup  (@lionkov)
    + max_background_threads  (@djwatson)
    + opt.lg_extent_max_active_fit  (@interwq)
    + opt.max_background_threads  (@djwatson)
    + opt.metadata_thp  (@interwq)
    + opt.thp  (@interwq)
    + stats.metadata_thp  (@interwq)

  Portability improvements:
  - Support GNU/kFreeBSD configuration.  (@paravoid)
  - Support m68k, nios2 and SH3 architectures.  (@paravoid)
  - Fall back to FD_CLOEXEC when O_CLOEXEC is unavailable.  (@zonyitoo)
  - Fix symbol listing for cross-compiling.  (@tamird)
  - Fix high bits computation on ARM.  (@davidtgoldblatt, @paravoid)
  - Disable the CPU_SPINWAIT macro for Power.  (@davidtgoldblatt, @marxin)
  - Fix MSVC 2015 & 2017 builds.  (@rustyx)
  - Improve RISC-V support.  (@EdSchouten)
  - Set name mangling script in strict mode.  (@nicolov)
  - Avoid MADV_HUGEPAGE on ARM.  (@marxin)
  - Modify configure to determine return value of strerror_r.
    (@davidtgoldblatt, @cferris1000)
  - Make sure CXXFLAGS is tested with CPP compiler.  (@nehaljwani)
  - Fix 32-bit build on MSVC.  (@rustyx)
  - Fix external symbol on MSVC.  (@maksqwe)
  - Avoid a printf format specifier warning.  (@jasone)
  - Add configure option --disable-initial-exec-tls which can allow jemalloc to
    be dynamically loaded after program startup.  (@davidtgoldblatt, @KenMacD)
  - AArch64: Add ILP32 support.  (@cmuellner)
  - Add --with-lg-vaddr configure option to support cross compiling.
    (@cmuellner, @davidtgoldblatt)

  Optimizations and refactors:
  - Improve active extent fit with extent_max_active_fit.  This considerably
    reduces fragmentation over time and improves virtual memory and metadata
    usage.  (@davidtgoldblatt, @interwq)
  - Eagerly coalesce large extents to reduce fragmentation.  (@interwq)
  - sdallocx: only read size info when page aligned (i.e. possibly sampled),
    which speeds up the sized deallocation path significantly.  (@interwq)
  - Avoid attempting new mappings for in place expansion with retain, since
    it rarely succeeds in practice and causes high overhead.  (@interwq)
  - Refactor OOM handling in newImpl.  (@wqfish)
  - Add internal fine-grained logging functionality for debugging use.
    (@davidtgoldblatt)
  - Refactor arena / tcache interactions.  (@davidtgoldblatt)
  - Refactor extent management with dumpable flag.  (@davidtgoldblatt)
  - Add runtime detection of lazy purging.  (@interwq)
  - Use pairing heap instead of red-black tree for extents_avail.  (@djwatson)
  - Use sysctl on startup in FreeBSD.  (@trasz)
  - Use thread local prng state instead of atomic.  (@djwatson)
  - Make decay to always purge one more extent than before, because in
    practice large extents are usually the ones that cross the decay threshold.
    Purging the additional extent helps save memory as well as reduce VM
    fragmentation.  (@interwq)
  - Fast division by dynamic values.  (@davidtgoldblatt)
  - Improve the fit for aligned allocation.  (@interwq, @edwinsmith)
  - Refactor extent_t bitpacking.  (@rkmisra)
  - Optimize the generated assembly for ticker operations.  (@davidtgoldblatt)
  - Convert stats printing to use a structured text emitter.  (@davidtgoldblatt)
  - Remove preserve_lru feature for extents management.  (@djwatson)
  - Consolidate two memory loads into one on the fast deallocation path.
    (@davidtgoldblatt, @interwq)

  Bug fixes (most of the issues are only relevant to jemalloc 5.0):
  - Fix deadlock with multithreaded fork in OS X.  (@davidtgoldblatt)
  - Validate returned file descriptor before use.  (@zonyitoo)
  - Fix a few background thread initialization and shutdown issues.  (@interwq)
  - Fix an extent coalesce + decay race by taking both coalescing extents off
    the LRU list.  (@interwq)
  - Fix potentially unbound increase during decay, caused by one thread keep
    stashing memory to purge while other threads generating new pages.  The
    number of pages to purge is checked to prevent this.  (@interwq)
  - Fix a FreeBSD bootstrap assertion.  (@strejda, @interwq)
  - Handle 32 bit mutex counters.  (@rkmisra)
  - Fix a indexing bug when creating background threads.  (@davidtgoldblatt,
    @binliu19)
  - Fix arguments passed to extent_init.  (@yuleniwo, @interwq)
  - Fix addresses used for ordering mutexes.  (@rkmisra)
  - Fix abort_conf processing during bootstrap.  (@interwq)
  - Fix include path order for out-of-tree builds.  (@cmuellner)

  Incompatible changes:
  - Remove --disable-thp.  (@interwq)
  - Remove mallctl interfaces:
    + config.thp  (@interwq)

  Documentation:
  - Add TUNING.md.  (@interwq, @davidtgoldblatt, @djwatson)

* 5.0.1 (July 1, 2017)

  This bugfix release fixes several issues, most of which are obscure enough
  that typical applications are not impacted.

  Bug fixes:
  - Update decay->nunpurged before purging, in order to avoid potential update
    races and subsequent incorrect purging volume.  (@interwq)
  - Only abort on dlsym(3) error if the failure impacts an enabled feature (lazy
    locking and/or background threads).  This mitigates an initialization
    failure bug for which we still do not have a clear reproduction test case.
    (@interwq)
  - Modify tsd management so that it neither crashes nor leaks if a thread's
    only allocation activity is to call free() after TLS destructors have been
    executed.  This behavior was observed when operating with GNU libc, and is
    unlikely to be an issue with other libc implementations.  (@interwq)
  - Mask signals during background thread creation.  This prevents signals from
    being inadvertently delivered to background threads.  (@jasone,
    @davidtgoldblatt, @interwq)
  - Avoid inactivity checks within background threads, in order to prevent
    recursive mutex acquisition.  (@interwq)
  - Fix extent_grow_retained() to use the specified hooks when the
    arena.<i>.extent_hooks mallctl is used to override the default hooks.
    (@interwq)
  - Add missing reentrancy support for custom extent hooks which allocate.
    (@interwq)
  - Post-fork(2), re-initialize the list of tcaches associated with each arena
    to contain no tcaches except the forking thread's.  (@interwq)
  - Add missing post-fork(2) mutex reinitialization for extent_grow_mtx.  This
    fixes potential deadlocks after fork(2).  (@interwq)
  - Enforce minimum autoconf version (currently 2.68), since 2.63 is known to
    generate corrupt configure scripts.  (@jasone)
  - Ensure that the configured page size (--with-lg-page) is no larger than the
    configured huge page size (--with-lg-hugepage).  (@jasone)

* 5.0.0 (June 13, 2017)

  Unlike all previous jemalloc releases, this release does not use naturally
  aligned "chunks" for virtual memory management, and instead uses page-aligned
  "extents".  This change has few externally visible effects, but the internal
  impacts are... extensive.  Many other internal changes combine to make this
  the most cohesively designed version of jemalloc so far, with ample
  opportunity for further enhancements.

  Continuous integration is now an integral aspect of development thanks to the
  efforts of @davidtgoldblatt, and the dev branch tends to remain reasonably
  stable on the tested platforms (Linux, FreeBSD, macOS, and Windows).  As a
  side effect the official release frequency may decrease over time.

  New features:
  - Implement optional per-CPU arena support; threads choose which arena to use
    based on current CPU rather than on fixed thread-->arena associations.
    (@interwq)
  - Implement two-phase decay of unused dirty pages.  Pages transition from
    dirty-->muzzy-->clean, where the first phase transition relies on
    madvise(... MADV_FREE) semantics, and the second phase transition discards
    pages such that they are replaced with demand-zeroed pages on next access.
    (@jasone)
  - Increase decay time resolution from seconds to milliseconds.  (@jasone)
  - Implement opt-in per CPU background threads, and use them for asynchronous
    decay-driven unused dirty page purging.  (@interwq)
  - Add mutex profiling, which collects a variety of statistics useful for
    diagnosing overhead/contention issues.  (@interwq)
  - Add C++ new/delete operator bindings.  (@djwatson)
  - Support manually created arena destruction, such that all data and metadata
    are discarded.  Add MALLCTL_ARENAS_DESTROYED for accessing merged stats
    associated with destroyed arenas.  (@jasone)
  - Add MALLCTL_ARENAS_ALL as a fixed index for use in accessing
    merged/destroyed arena statistics via mallctl.  (@jasone)
  - Add opt.abort_conf to optionally abort if invalid configuration options are
    detected during initialization.  (@interwq)
  - Add opt.stats_print_opts, so that e.g. JSON output can be selected for the
    stats dumped during exit if opt.stats_print is true.  (@jasone)
  - Add --with-version=VERSION for use when embedding jemalloc into another
    project's git repository.  (@jasone)
  - Add --disable-thp to support cross compiling.  (@jasone)
  - Add --with-lg-hugepage to support cross compiling.  (@jasone)