Refactor code such that arena_mapbits_{large,small}_set() always
preserves the unzeroed flag, and manually manipulate the unzeroed flag
in the one case where it actually gets reset (in arena_chunk_purge()).
This fixes unzeroed preservation bugs in arena_run_split() and
arena_ralloc_large_grow(). These bugs caused large calloc() to return
non-zeroed memory under some circumstances.
Add the --enable-mremap option, and disable the use of mremap(2) by
default, for the same reason that freeing chunks via munmap(2) is
disabled by default on Linux: semi-permanent VM map fragmentation.
Fix chunk_recycle() to correctly compute trailsize and re-insert
trailing chunks. This fixes a major virtual memory leak.
Simplify chunk_record() to avoid dropping/re-acquiring chunks_mtx.
Simplify chunk_alloc_mmap() to no longer attempt map extension. The
extra complexity isn't warranted, because although in the success case
it saves one system call as compared to immediately falling back to
chunk_alloc_mmap_slow(), it also makes the failure case even more
expensive. This simplification removes two bugs:
- For Windows platforms, pages_unmap() wasn't being called for unaligned
mappings prior to falling back to chunk_alloc_mmap_slow(). This
caused permanent virtual memory leaks.
- For non-Windows platforms, alignment greater than chunksize caused
pages_map() to be called with size 0 when attempting map extension.
This always resulted in an mmap() error, and subsequent fallback to
chunk_alloc_mmap_slow().
If an application wants to override je_malloc_message, it is better to define
the symbol locally than to change its value in main(), which might be too late
for various reasons.
Due to je_malloc_message being initialized in util.c, statically linking
jemalloc with an application defining je_malloc_message fails due to
"multiple definition of" the symbol.
Defining it without a value (like je_malloc_conf) makes it more easily
overridable.
Further optimize arena_salloc() to only look at the binind chunk map
bits in the common case.
Add more sanity checks to arena_salloc() that detect chunk map
inconsistencies for large allocations (whether due to allocator bugs or
application bugs).
Embed the bin index for small page runs into the chunk page map, in
order to omit [...] in the following dependent load sequence:
ptr-->mapelm-->[run-->bin-->]bin_info
Move various non-critcal code out of the inlined function chain into
helper functions (tcache_event_hard(), arena_dalloc_small(), and
locking).
Theses newly added macros will be used to implement the equivalent under
MSVC. Also, move the definitions to headers, where they make more sense,
and for some, are even more useful there (e.g. malloc).
Using errno on win32 doesn't quite work, because the value set in a shared
library can't be read from e.g. an executable calling the function setting
errno.
At the same time, since buferror always uses errno/GetLastError, don't pass
it.
MSVC doesn't support C99, and building as C++ to be able to use them is
dangerous, as C++ and C99 are incompatible.
Introduce a VARIABLE_ARRAY macro that either uses VLA when supported,
or alloca() otherwise. Note that using alloca() inside loops doesn't
quite work like VLAs, thus the use of VARIABLE_ARRAY there is discouraged.
It might be worth investigating ways to check whether VARIABLE_ARRAY is
used in such context at runtime in debug builds and bail out if that
happens.
MSVC doesn't support C99, and as such doesn't support designated
initialization of structs and unions. As there is never a mix of
indexed and named nodes, it is pretty straightforward to use a
different type for each.
Fix a potential deadlock that could occur during interval- and
growth-triggered heap profile dumps.
Fix an off-by-one heap profile statistics bug that could be observed in
interval- and growth-triggered heap profiles.
Fix heap profile dump filename sequence numbers (regression during
conversion to malloc_snprintf()).
Remove mmap_unaligned, which was used to heuristically decide whether to
optimistically call mmap() in such a way that could reduce the total
number of system calls. If I remember correctly, the intention of
mmap_unaligned was to avoid always executing the slow path in the
presence of ASLR. However, that reasoning seems to have been based on a
flawed understanding of how ASLR actually works. Although ASLR
apparently causes mmap() to ignore address requests, it does not cause
total placement randomness, so there is a reasonable expectation that
iterative mmap() calls will start returning chunk-aligned mappings once
the first chunk has been properly aligned.
Fix chunk_alloc_dss() to zero memory when requested.
Fix chunk_dealloc() to avoid chunk_dealloc_mmap() for dss-allocated
memory.
Fix huge_palloc() to always junk fill when requested.
Improve chunk_recycle() to report that memory is zeroed as a side effect
of pages_purge().
Fix a memory corruption bug in chunk_alloc_dss() that was due to
claiming newly allocated memory is zeroed.
Reverse order of preference between mmap() and sbrk() to prefer mmap().
Clean up management of 'zero' parameter in chunk_alloc*().
These flags take unsigned values, but they were fed with signed values
taken with va_arg, and that led to sign extension in cases where the
corresponding value has the most significant bit set.
Clean up a few config-related conditionals to avoid unnecessary
dependencies on prof symbols. Use cassert() rather than assert()
everywhere that it's appropriate.
Change the "opt.lg_prof_sample" default from 0 to 19 (1 B to 512 KiB).
Change the "opt.prof_accum" default from true to false.
Add the "opt.prof_final" mallctl, so that "opt.prof_prefix" need not be
abused to disable final profile dumping.
Add the --disable-munmap option, remove the configure test that
attempted to detect the VM allocation quirk known to exist on Linux
x86[_64], and make --disable-munmap implicit on Linux.
Add a configure test to determine whether common mmap()/munmap()
patterns cause VM map holes, and only use munmap() to discard unused
chunks if the problem does not exist.
Unify the chunk caching for mmap and dss.
Fix options processing to limit lg_chunk to be large enough that
redzones will always fit.
Always disable redzone by default, even when --enable-debug is
specified. The memory overhead for redzones can be substantial, which
makes this feature something that should only be opted into.
