Following are change highlights associated with official releases.  Important
bug fixes are all mentioned, but internal enhancements are omitted here for
brevity (even though they are more fun to write about).  Much more detail can be
found in the git revision history:

    http://www.canonware.com/cgi-bin/gitweb.cgi?p=jemalloc.git
    git://canonware.com/jemalloc.git

* 2.2.1 (March 30, 2011)

  Bug fixes:
  - Implement atomic operations for x86/x64.  This fixes compilation failures
    for versions of gcc that are still in wide use.
  - Fix an assertion in arena_purge().

* 2.2.0 (March 22, 2011)

  This version incorporates several improvements to algorithms and data
  structures that tend to reduce fragmentation and increase speed.

  New features:
  - Add the "stats.cactive" mallctl.
  - Update pprof (from google-perftools 1.7).
  - Improve backtracing-related configuration logic, and add the
    --disable-prof-libgcc option.

  Bug fixes:
  - Change default symbol visibility from "internal", to "hidden", which
    decreases the overhead of library-internal function calls.
  - Fix symbol visibility so that it is also set on OS X.
  - Fix a build dependency regression caused by the introduction of the .pic.o
    suffix for PIC object files.
  - Add missing checks for mutex initialization failures.
  - Don't use libgcc-based backtracing except on x64, where it is known to work.
  - Fix deadlocks on OS X that were due to memory allocation in
    pthread_mutex_lock().
  - Heap profiling-specific fixes:
    + Fix memory corruption due to integer overflow in small region index
      computation, when using a small enough sample interval that profiling
      context pointers are stored in small run headers.
    + Fix a bootstrap ordering bug that only occurred with TLS disabled.
    + Fix a rallocm() rsize bug.
    + Fix error detection bugs for aligned memory allocation.

* 2.1.3 (March 14, 2011)

  Bug fixes:
  - Fix a cpp logic regression (due to the "thread.{de,}allocatedp" mallctl fix
    for OS X in 2.1.2).
  - Fix a "thread.arena" mallctl bug.
  - Fix a thread cache stats merging bug.

* 2.1.2 (March 2, 2011)

  Bug fixes:
  - Fix "thread.{de,}allocatedp" mallctl for OS X.
  - Add missing jemalloc.a to build system.

* 2.1.1 (January 31, 2011)

  Bug fixes:
  - Fix aligned huge reallocation (affected allocm()).
  - Fix the ALLOCM_LG_ALIGN macro definition.
  - Fix a heap dumping deadlock.
  - Fix a "thread.arena" mallctl bug.

* 2.1.0 (December 3, 2010)

  This version incorporates some optimizations that can't quite be considered
  bug fixes.

  New features:
  - Use Linux's mremap(2) for huge object reallocation when possible.
  - Avoid locking in mallctl*() when possible.
  - Add the "thread.[de]allocatedp" mallctl's.
  - Convert the manual page source from roff to DocBook, and generate both roff
    and HTML manuals.

  Bug fixes:
  - Fix a crash due to incorrect bootstrap ordering.  This only impacted
    --enable-debug --enable-dss configurations.
  - Fix a minor statistics bug for mallctl("swap.avail", ...).

* 2.0.1 (October 29, 2010)

  Bug fixes:
  - Fix a race condition in heap profiling that could cause undefined behavior
    if "opt.prof_accum" were disabled.
  - Add missing mutex unlocks for some OOM error paths in the heap profiling
    code.
  - Fix a compilation error for non-C99 builds.

* 2.0.0 (October 24, 2010)

  This version focuses on the experimental *allocm() API, and on improved
  run-time configuration/introspection.  Nonetheless, numerous performance
  improvements are also included.

  New features:
  - Implement the experimental {,r,s,d}allocm() API, which provides a superset
    of the functionality available via malloc(), calloc(), posix_memalign(),
    realloc(), malloc_usable_size(), and free().  These functions can be used to
    allocate/reallocate aligned zeroed memory, ask for optional extra memory
    during reallocation, prevent object movement during reallocation, etc.
  - Replace JEMALLOC_OPTIONS/JEMALLOC_PROF_PREFIX with MALLOC_CONF, which is
    more human-readable, and more flexible.  For example:
      JEMALLOC_OPTIONS=AJP
    is now:
      MALLOC_CONF=abort:true,fill:true,stats_print:true
  - Port to Apple OS X.  Sponsored by Mozilla.
  - Make it possible for the application to control thread-->arena mappings via
    the "thread.arena" mallctl.
  - Add compile-time support for all TLS-related functionality via pthreads TSD.
    This is mainly of interest for OS X, which does not support TLS, but has a
    TSD implementation with similar performance.
  - Override memalign() and valloc() if they are provided by the system.
  - Add the "arenas.purge" mallctl, which can be used to synchronously purge all
    dirty unused pages.
  - Make cumulative heap profiling data optional, so that it is possible to
    limit the amount of memory consumed by heap profiling data structures.
  - Add per thread allocation counters that can be accessed via the
    "thread.allocated" and "thread.deallocated" mallctls.

  Incompatible changes:
  - Remove JEMALLOC_OPTIONS and malloc_options (see MALLOC_CONF above).
  - Increase default backtrace depth from 4 to 128 for heap profiling.
  - Disable interval-based profile dumps by default.

  Bug fixes:
  - Remove bad assertions in fork handler functions.  These assertions could
    cause aborts for some combinations of configure settings.
  - Fix strerror_r() usage to deal with non-standard semantics in GNU libc.
  - Fix leak context reporting.  This bug tended to cause the number of contexts
    to be underreported (though the reported number of objects and bytes were
    correct).
  - Fix a realloc() bug for large in-place growing reallocation.  This bug could
    cause memory corruption, but it was hard to trigger.
  - Fix an allocation bug for small allocations that could be triggered if
    multiple threads raced to create a new run of backing pages.
  - Enhance the heap profiler to trigger samples based on usable size, rather
    than request size.
  - Fix a heap profiling bug due to sometimes losing track of requested object
    size for sampled objects.

* 1.0.3 (August 12, 2010)

  Bug fixes:
  - Fix the libunwind-based implementation of stack backtracing (used for heap
    profiling).  This bug could cause zero-length backtraces to be reported.
  - Add a missing mutex unlock in library initialization code.  If multiple
    threads raced to initialize malloc, some of them could end up permanently
    blocked.

* 1.0.2 (May 11, 2010)

  Bug fixes:
  - Fix junk filling of large objects, which could cause memory corruption.
  - Add MAP_NORESERVE support for chunk mapping, because otherwise virtual
    memory limits could cause swap file configuration to fail.  Contributed by
    Jordan DeLong.

* 1.0.1 (April 14, 2010)

  Bug fixes:
  - Fix compilation when --enable-fill is specified.
  - Fix threads-related profiling bugs that affected accuracy and caused memory
    to be leaked during thread exit.
  - Fix dirty page purging race conditions that could cause crashes.
  - Fix crash in tcache flushing code during thread destruction.

* 1.0.0 (April 11, 2010)

  This release focuses on speed and run-time introspection.  Numerous
  algorithmic improvements make this release substantially faster than its
  predecessors.

  New features:
  - Implement autoconf-based configuration system.
  - Add mallctl*(), for the purposes of introspection and run-time
    configuration.
  - Make it possible for the application to manually flush a thread's cache, via
    the "tcache.flush" mallctl.
  - Base maximum dirty page count on proportion of active memory.
  - Compute various addtional run-time statistics, including per size class
    statistics for large objects.
  - Expose malloc_stats_print(), which can be called repeatedly by the
    application.
  - Simplify the malloc_message() signature to only take one string argument,
    and incorporate an opaque data pointer argument for use by the application
    in combination with malloc_stats_print().
  - Add support for allocation backed by one or more swap files, and allow the
    application to disable over-commit if swap files are in use.
  - Implement allocation profiling and leak checking.

  Removed features:
  - Remove the dynamic arena rebalancing code, since thread-specific caching
    reduces its utility.

  Bug fixes:
  - Modify chunk allocation to work when address space layout randomization
    (ASLR) is in use.
  - Fix thread cleanup bugs related to TLS destruction.
  - Handle 0-size allocation requests in posix_memalign().
  - Fix a chunk leak.  The leaked chunks were never touched, so this impacted
    virtual memory usage, but not physical memory usage.

* linux_2008082[78]a (August 27/28, 2008)

  These snapshot releases are the simple result of incorporating Linux-specific
  support into the FreeBSD malloc sources.

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