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Library Jemalloc updated to 5.0.1 (#721)

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2017-11-26 17:46:07 +01:00
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@@ -1,10 +1,727 @@
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:
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
* 5.0.1 (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,
@davidgoldblatt, @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)
- Add mallctl interfaces (various authors):
+ background_thread
+ opt.abort_conf
+ opt.retain
+ opt.percpu_arena
+ opt.background_thread
+ opt.{dirty,muzzy}_decay_ms
+ opt.stats_print_opts
+ arena.<i>.initialized
+ arena.<i>.destroy
+ arena.<i>.{dirty,muzzy}_decay_ms
+ arena.<i>.extent_hooks
+ arenas.{dirty,muzzy}_decay_ms
+ arenas.bin.<i>.slab_size
+ arenas.nlextents
+ arenas.lextent.<i>.size
+ arenas.create
+ stats.background_thread.{num_threads,num_runs,run_interval}
+ stats.mutexes.{ctl,background_thread,prof,reset}.
{num_ops,num_spin_acq,num_wait,max_wait_time,total_wait_time,max_num_thds,
num_owner_switch}
+ stats.arenas.<i>.{dirty,muzzy}_decay_ms
+ stats.arenas.<i>.uptime
+ stats.arenas.<i>.{pmuzzy,base,internal,resident}
+ stats.arenas.<i>.{dirty,muzzy}_{npurge,nmadvise,purged}
+ stats.arenas.<i>.bins.<j>.{nslabs,reslabs,curslabs}
+ stats.arenas.<i>.bins.<j>.mutex.
{num_ops,num_spin_acq,num_wait,max_wait_time,total_wait_time,max_num_thds,
num_owner_switch}
+ stats.arenas.<i>.lextents.<j>.{nmalloc,ndalloc,nrequests,curlextents}
+ stats.arenas.i.mutexes.{large,extent_avail,extents_dirty,extents_muzzy,
extents_retained,decay_dirty,decay_muzzy,base,tcache_list}.
{num_ops,num_spin_acq,num_wait,max_wait_time,total_wait_time,max_num_thds,
num_owner_switch}
Portability improvements:
- Improve reentrant allocation support, such that deadlock is less likely if
e.g. a system library call in turn allocates memory. (@davidtgoldblatt,
@interwq)
- Support static linking of jemalloc with glibc. (@djwatson)
Optimizations and refactors:
- Organize virtual memory as "extents" of virtual memory pages, rather than as
naturally aligned "chunks", and store all metadata in arbitrarily distant
locations. This reduces virtual memory external fragmentation, and will
interact better with huge pages (not yet explicitly supported). (@jasone)
- Fold large and huge size classes together; only small and large size classes
remain. (@jasone)
- Unify the allocation paths, and merge most fast-path branching decisions.
(@davidtgoldblatt, @interwq)
- Embed per thread automatic tcache into thread-specific data, which reduces
conditional branches and dereferences. Also reorganize tcache to increase
fast-path data locality. (@interwq)
- Rewrite atomics to closely model the C11 API, convert various
synchronization from mutex-based to atomic, and use the explicit memory
ordering control to resolve various hypothetical races without increasing
synchronization overhead. (@davidtgoldblatt)
- Extensively optimize rtree via various methods:
+ Add multiple layers of rtree lookup caching, since rtree lookups are now
part of fast-path deallocation. (@interwq)
+ Determine rtree layout at compile time. (@jasone)
+ Make the tree shallower for common configurations. (@jasone)
+ Embed the root node in the top-level rtree data structure, thus avoiding
one level of indirection. (@jasone)
+ Further specialize leaf elements as compared to internal node elements,
and directly embed extent metadata needed for fast-path deallocation.
(@jasone)
+ Ignore leading always-zero address bits (architecture-specific).
(@jasone)
- Reorganize headers (ongoing work) to make them hermetic, and disentangle
various module dependencies. (@davidtgoldblatt)
- Convert various internal data structures such as size class metadata from
boot-time-initialized to compile-time-initialized. Propagate resulting data
structure simplifications, such as making arena metadata fixed-size.
(@jasone)
- Simplify size class lookups when constrained to size classes that are
multiples of the page size. This speeds lookups, but the primary benefit is
complexity reduction in code that was the source of numerous regressions.
(@jasone)
- Lock individual extents when possible for localized extent operations,
rather than relying on a top-level arena lock. (@davidtgoldblatt, @jasone)
- Use first fit layout policy instead of best fit, in order to improve
packing. (@jasone)
- If munmap(2) is not in use, use an exponential series to grow each arena's
virtual memory, so that the number of disjoint virtual memory mappings
remains low. (@jasone)
- Implement per arena base allocators, so that arenas never share any virtual
memory pages. (@jasone)
- Automatically generate private symbol name mangling macros. (@jasone)
Incompatible changes:
- Replace chunk hooks with an expanded/normalized set of extent hooks.
(@jasone)
- Remove ratio-based purging. (@jasone)
- Remove --disable-tcache. (@jasone)
- Remove --disable-tls. (@jasone)
- Remove --enable-ivsalloc. (@jasone)
- Remove --with-lg-size-class-group. (@jasone)
- Remove --with-lg-tiny-min. (@jasone)
- Remove --disable-cc-silence. (@jasone)
- Remove --enable-code-coverage. (@jasone)
- Remove --disable-munmap (replaced by opt.retain). (@jasone)
- Remove Valgrind support. (@jasone)
- Remove quarantine support. (@jasone)
- Remove redzone support. (@jasone)
- Remove mallctl interfaces (various authors):
+ config.munmap
+ config.tcache
+ config.tls
+ config.valgrind
+ opt.lg_chunk
+ opt.purge
+ opt.lg_dirty_mult
+ opt.decay_time
+ opt.quarantine
+ opt.redzone
+ opt.thp
+ arena.<i>.lg_dirty_mult
+ arena.<i>.decay_time
+ arena.<i>.chunk_hooks
+ arenas.initialized
+ arenas.lg_dirty_mult
+ arenas.decay_time
+ arenas.bin.<i>.run_size
+ arenas.nlruns
+ arenas.lrun.<i>.size
+ arenas.nhchunks
+ arenas.hchunk.<i>.size
+ arenas.extend
+ stats.cactive
+ stats.arenas.<i>.lg_dirty_mult
+ stats.arenas.<i>.decay_time
+ stats.arenas.<i>.metadata.{mapped,allocated}
+ stats.arenas.<i>.{npurge,nmadvise,purged}
+ stats.arenas.<i>.huge.{allocated,nmalloc,ndalloc,nrequests}
+ stats.arenas.<i>.bins.<j>.{nruns,reruns,curruns}
+ stats.arenas.<i>.lruns.<j>.{nmalloc,ndalloc,nrequests,curruns}
+ stats.arenas.<i>.hchunks.<j>.{nmalloc,ndalloc,nrequests,curhchunks}
Bug fixes:
- Improve interval-based profile dump triggering to dump only one profile when
a single allocation's size exceeds the interval. (@jasone)
- Use prefixed function names (as controlled by --with-jemalloc-prefix) when
pruning backtrace frames in jeprof. (@jasone)
* 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)
* 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
function, to a location that gets executed even if the application installs
a custom chunk allocation function. This resolves a virtual memory leak.
(@buchgr)
- Fix a potential tsd cleanup leak. (@cferris1000, @jasone)
- Fix run quantization. In practice this bug had no impact unless
applications requested memory with alignment exceeding one page.
(@jasone, @djwatson)
- Fix LinuxThreads-specific bootstrapping deadlock. (Cosmin Paraschiv)
- jeprof:
+ Don't discard curl options if timeout is not defined. (@djwatson)
+ Detect failed profile fetches. (@djwatson)
- Fix stats.arenas.<i>.{dss,lg_dirty_mult,decay_time,pactive,pdirty} for
--disable-stats case. (@jasone)
* 4.0.4 (October 24, 2015)
This bugfix release fixes another xallocx() regression. No other regressions
have come to light in over a month, so this is likely a good starting point
for people who prefer to wait for "dot one" releases with all the major issues
shaken out.
Bug fixes:
- Fix xallocx(..., MALLOCX_ZERO to zero the last full trailing page of large
allocations that have been randomly assigned an offset of 0 when
--enable-cache-oblivious configure option is enabled.
* 4.0.3 (September 24, 2015)
This bugfix release continues the trend of xallocx() and heap profiling fixes.
Bug fixes:
- Fix xallocx(..., MALLOCX_ZERO) to zero all trailing bytes of large
allocations when --enable-cache-oblivious configure option is enabled.
- Fix xallocx(..., MALLOCX_ZERO) to zero trailing bytes of huge allocations
when resizing from/to a size class that is not a multiple of the chunk size.
- Fix prof_tctx_dump_iter() to filter out nodes that were created after heap
profile dumping started.
- Work around a potentially bad thread-specific data initialization
interaction with NPTL (glibc's pthreads implementation).
* 4.0.2 (September 21, 2015)
This bugfix release addresses a few bugs specific to heap profiling.
Bug fixes:
- Fix ixallocx_prof_sample() to never modify nor create sampled small
allocations. xallocx() is in general incapable of moving small allocations,
so this fix removes buggy code without loss of generality.
- Fix irallocx_prof_sample() to always allocate large regions, even when
alignment is non-zero.
- Fix prof_alloc_rollback() to read tdata from thread-specific data rather
than dereferencing a potentially invalid tctx.
* 4.0.1 (September 15, 2015)
This is a bugfix release that is somewhat high risk due to the amount of
refactoring required to address deep xallocx() problems. As a side effect of
these fixes, xallocx() now tries harder to partially fulfill requests for
optional extra space. Note that a couple of minor heap profiling
optimizations are included, but these are better thought of as performance
fixes that were integral to disovering most of the other bugs.
Optimizations:
- Avoid a chunk metadata read in arena_prof_tctx_set(), since it is in the
fast path when heap profiling is enabled. Additionally, split a special
case out into arena_prof_tctx_reset(), which also avoids chunk metadata
reads.
- Optimize irallocx_prof() to optimistically update the sampler state. The
prior implementation appears to have been a holdover from when
rallocx()/xallocx() functionality was combined as rallocm().
Bug fixes:
- Fix TLS configuration such that it is enabled by default for platforms on
which it works correctly.
- Fix arenas_cache_cleanup() and arena_get_hard() to handle
allocation/deallocation within the application's thread-specific data
cleanup functions even after arenas_cache is torn down.
- Fix xallocx() bugs related to size+extra exceeding HUGE_MAXCLASS.
- Fix chunk purge hook calls for in-place huge shrinking reallocation to
specify the old chunk size rather than the new chunk size. This bug caused
no correctness issues for the default chunk purge function, but was
visible to custom functions set via the "arena.<i>.chunk_hooks" mallctl.
- Fix heap profiling bugs:
+ Fix heap profiling to distinguish among otherwise identical sample sites
with interposed resets (triggered via the "prof.reset" mallctl). This bug
could cause data structure corruption that would most likely result in a
segfault.
+ Fix irealloc_prof() to prof_alloc_rollback() on OOM.
+ Make one call to prof_active_get_unlocked() per allocation event, and use
the result throughout the relevant functions that handle an allocation
event. Also add a missing check in prof_realloc(). These fixes protect
allocation events against concurrent prof_active changes.
+ Fix ixallocx_prof() to pass usize_max and zero to ixallocx_prof_sample()
in the correct order.
+ Fix prof_realloc() to call prof_free_sampled_object() after calling
prof_malloc_sample_object(). Prior to this fix, if tctx and old_tctx were
the same, the tctx could have been prematurely destroyed.
- Fix portability bugs:
+ Don't bitshift by negative amounts when encoding/decoding run sizes in
chunk header maps. This affected systems with page sizes greater than 8
KiB.
+ Rename index_t to szind_t to avoid an existing type on Solaris.
+ Add JEMALLOC_CXX_THROW to the memalign() function prototype, in order to
match glibc and avoid compilation errors when including both
jemalloc/jemalloc.h and malloc.h in C++ code.
+ Don't assume that /bin/sh is appropriate when running size_classes.sh
during configuration.
+ Consider __sparcv9 a synonym for __sparc64__ when defining LG_QUANTUM.
+ Link tests to librt if it contains clock_gettime(2).
* 4.0.0 (August 17, 2015)
This version contains many speed and space optimizations, both minor and
major. The major themes are generalization, unification, and simplification.
Although many of these optimizations cause no visible behavior change, their
cumulative effect is substantial.
New features:
- Normalize size class spacing to be consistent across the complete size
range. By default there are four size classes per size doubling, but this
is now configurable via the --with-lg-size-class-group option. Also add the
--with-lg-page, --with-lg-page-sizes, --with-lg-quantum, and
--with-lg-tiny-min options, which can be used to tweak page and size class
settings. Impacts:
+ Worst case performance for incrementally growing/shrinking reallocation
is improved because there are far fewer size classes, and therefore
copying happens less often.
+ Internal fragmentation is limited to 20% for all but the smallest size
classes (those less than four times the quantum). (1B + 4 KiB)
and (1B + 4 MiB) previously suffered nearly 50% internal fragmentation.
+ Chunk fragmentation tends to be lower because there are fewer distinct run
sizes to pack.
- Add support for explicit tcaches. The "tcache.create", "tcache.flush", and
"tcache.destroy" mallctls control tcache lifetime and flushing, and the
MALLOCX_TCACHE(tc) and MALLOCX_TCACHE_NONE flags to the *allocx() API
control which tcache is used for each operation.
- Implement per thread heap profiling, as well as the ability to
enable/disable heap profiling on a per thread basis. Add the "prof.reset",
"prof.lg_sample", "thread.prof.name", "thread.prof.active",
"opt.prof_thread_active_init", "prof.thread_active_init", and
"thread.prof.active" mallctls.
- Add support for per arena application-specified chunk allocators, configured
via the "arena.<i>.chunk_hooks" mallctl.
- Refactor huge allocation to be managed by arenas, so that arenas now
function as general purpose independent allocators. This is important in
the context of user-specified chunk allocators, aside from the scalability
benefits. Related new statistics:
+ The "stats.arenas.<i>.huge.allocated", "stats.arenas.<i>.huge.nmalloc",
"stats.arenas.<i>.huge.ndalloc", and "stats.arenas.<i>.huge.nrequests"
mallctls provide high level per arena huge allocation statistics.
+ The "arenas.nhchunks", "arenas.hchunk.<i>.size",
"stats.arenas.<i>.hchunks.<j>.nmalloc",
"stats.arenas.<i>.hchunks.<j>.ndalloc",
"stats.arenas.<i>.hchunks.<j>.nrequests", and
"stats.arenas.<i>.hchunks.<j>.curhchunks" mallctls provide per size class
statistics.
- Add the 'util' column to malloc_stats_print() output, which reports the
proportion of available regions that are currently in use for each small
size class.
- Add "alloc" and "free" modes for for junk filling (see the "opt.junk"
mallctl), so that it is possible to separately enable junk filling for
allocation versus deallocation.
- Add the jemalloc-config script, which provides information about how
jemalloc was configured, and how to integrate it into application builds.
- Add metadata statistics, which are accessible via the "stats.metadata",
"stats.arenas.<i>.metadata.mapped", and
"stats.arenas.<i>.metadata.allocated" mallctls.
- Add the "stats.resident" mallctl, which reports the upper limit of
physically resident memory mapped by the allocator.
- Add per arena control over unused dirty page purging, via the
"arenas.lg_dirty_mult", "arena.<i>.lg_dirty_mult", and
"stats.arenas.<i>.lg_dirty_mult" mallctls.
- Add the "prof.gdump" mallctl, which makes it possible to toggle the gdump
feature on/off during program execution.
- Add sdallocx(), which implements sized deallocation. The primary
optimization over dallocx() is the removal of a metadata read, which often
suffers an L1 cache miss.
- Add missing header includes in jemalloc/jemalloc.h, so that applications
only have to #include <jemalloc/jemalloc.h>.
- Add support for additional platforms:
+ Bitrig
+ Cygwin
+ DragonFlyBSD
+ iOS
+ OpenBSD
+ OpenRISC/or1k
Optimizations:
- Maintain dirty runs in per arena LRUs rather than in per arena trees of
dirty-run-containing chunks. In practice this change significantly reduces
dirty page purging volume.
- Integrate whole chunks into the unused dirty page purging machinery. This
reduces the cost of repeated huge allocation/deallocation, because it
effectively introduces a cache of chunks.
- Split the arena chunk map into two separate arrays, in order to increase
cache locality for the frequently accessed bits.
- Move small run metadata out of runs, into arena chunk headers. This reduces
run fragmentation, smaller runs reduce external fragmentation for small size
classes, and packed (less uniformly aligned) metadata layout improves CPU
cache set distribution.
- Randomly distribute large allocation base pointer alignment relative to page
boundaries in order to more uniformly utilize CPU cache sets. This can be
disabled via the --disable-cache-oblivious configure option, and queried via
the "config.cache_oblivious" mallctl.
- Micro-optimize the fast paths for the public API functions.
- Refactor thread-specific data to reside in a single structure. This assures
that only a single TLS read is necessary per call into the public API.
- Implement in-place huge allocation growing and shrinking.
- Refactor rtree (radix tree for chunk lookups) to be lock-free, and make
additional optimizations that reduce maximum lookup depth to one or two
levels. This resolves what was a concurrency bottleneck for per arena huge
allocation, because a global data structure is critical for determining
which arenas own which huge allocations.
Incompatible changes:
- Replace --enable-cc-silence with --disable-cc-silence to suppress spurious
warnings by default.
- Assure that the constness of malloc_usable_size()'s return type matches that
of the system implementation.
- Change the heap profile dump format to support per thread heap profiling,
rename pprof to jeprof, and enhance it with the --thread=<n> option. As a
result, the bundled jeprof must now be used rather than the upstream
(gperftools) pprof.
- Disable "opt.prof_final" by default, in order to avoid atexit(3), which can
internally deadlock on some platforms.
- Change the "arenas.nlruns" mallctl type from size_t to unsigned.
- Replace the "stats.arenas.<i>.bins.<j>.allocated" mallctl with
"stats.arenas.<i>.bins.<j>.curregs".
- Ignore MALLOC_CONF in set{uid,gid,cap} binaries.
- Ignore MALLOCX_ARENA(a) in dallocx(), in favor of using the
MALLOCX_TCACHE(tc) and MALLOCX_TCACHE_NONE flags to control tcache usage.
Removed features:
- Remove the *allocm() API, which is superseded by the *allocx() API.
- Remove the --enable-dss options, and make dss non-optional on all platforms
which support sbrk(2).
- Remove the "arenas.purge" mallctl, which was obsoleted by the
"arena.<i>.purge" mallctl in 3.1.0.
- Remove the unnecessary "opt.valgrind" mallctl; jemalloc automatically
detects whether it is running inside Valgrind.
- Remove the "stats.huge.allocated", "stats.huge.nmalloc", and
"stats.huge.ndalloc" mallctls.
- Remove the --enable-mremap option.
- Remove the "stats.chunks.current", "stats.chunks.total", and
"stats.chunks.high" mallctls.
Bug fixes:
- Fix the cactive statistic to decrease (rather than increase) when active
memory decreases. This regression was first released in 3.5.0.
- Fix OOM handling in memalign() and valloc(). A variant of this bug existed
in all releases since 2.0.0, which introduced these functions.
- Fix an OOM-related regression in arena_tcache_fill_small(), which could
cause cache corruption on OOM. This regression was present in all releases
from 2.2.0 through 3.6.0.
- Fix size class overflow handling for malloc(), posix_memalign(), memalign(),
calloc(), and realloc() when profiling is enabled.
- Fix the "arena.<i>.dss" mallctl to return an error if "primary" or
"secondary" precedence is specified, but sbrk(2) is not supported.
- Fix fallback lg_floor() implementations to handle extremely large inputs.
- Ensure the default purgeable zone is after the default zone on OS X.
- Fix latent bugs in atomic_*().
- Fix the "arena.<i>.dss" mallctl to handle read-only calls.
- Fix tls_model configuration to enable the initial-exec model when possible.
- Mark malloc_conf as a weak symbol so that the application can override it.
- Correctly detect glibc's adaptive pthread mutexes.
- Fix the --without-export configure option.
* 3.6.0 (March 31, 2014)
This version contains a critical bug fix for a regression present in 3.5.0 and
@@ -21,7 +738,7 @@ found in the git revision history:
backtracing to be reliable.
- Use dss allocation precedence for huge allocations as well as small/large
allocations.
- Fix test assertion failure message formatting. This bug did not manifect on
- Fix test assertion failure message formatting. This bug did not manifest on
x86_64 systems because of implementation subtleties in va_list.
- Fix inconsequential test failures for hash and SFMT code.
@@ -516,7 +1233,7 @@ found in the git revision history:
- 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
- Compute various additional run-time statistics, including per size class
statistics for large objects.
- Expose malloc_stats_print(), which can be called repeatedly by the
application.