Avoid writing to uninitialized TLS as a side effect of deallocation.
Initializing TLS during deallocation is unsafe because it is possible
that a thread never did any allocation, and that TLS has already been
deallocated by the threads library, resulting in write-after-free
corruption. These fixes affect prof_tdata and quarantine; all other
uses of TLS are already safe, whether intentionally (as for tcache) or
unintentionally (as for arenas).
Add a library constructor for jemalloc that initializes the allocator.
This fixes a race that could occur if threads were created by the main
thread prior to any memory allocation, followed by fork(2), and then
memory allocation in the child process.
Fix the prefork/postfork functions to acquire/release the ctl, prof, and
rtree mutexes. This fixes various fork() child process deadlocks, but
one possible deadlock remains (intentionally) unaddressed: prof
backtracing can acquire runtime library mutexes, so deadlock is still
possible if heap profiling is enabled during fork(). This deadlock is
known to be a real issue in at least the case of libgcc-based
backtracing.
Reported by tfengjun.
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.
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()).
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.
Implement Valgrind support, as well as the redzone and quarantine
features, which help Valgrind detect memory errors. Redzones are only
implemented for small objects because the changes necessary to support
redzones around large and huge objects are complicated by in-place
reallocation, to the point that it isn't clear that the maintenance
burden is worth the incremental improvement to Valgrind support.
Merge arena_salloc() and arena_salloc_demote().
Refactor i[v]salloc() to expose the 'demote' option.
Remove ephemeral mutexes from the prof machinery, and remove
malloc_mutex_destroy(). This simplifies mutex management on systems
that call malloc()/free() inside pthread_mutex_{create,destroy}().
Add atomic_*_u() for operation on unsigned values.
Fix prof_printf() to call malloc_vsnprintf() rather than
malloc_snprintf().
Implement tsd, which is a TLS/TSD abstraction that uses one or both
internally. Modify bootstrapping such that no tsd's are utilized until
allocation is safe.
Remove malloc_[v]tprintf(), and use malloc_snprintf() instead.
Fix %p argument size handling in malloc_vsnprintf().
Fix a long-standing statistics-related bug in the "thread.arena"
mallctl that could cause crashes due to linked list corruption.
Remove opt.lg_prof_bt_max, and hard code it to 7. The original
intention of this option was to enable faster backtracing by limiting
backtrace depth. However, this makes graphical pprof output very
difficult to interpret. In practice, decreasing sampling frequency is a
better mechanism for limiting profiling overhead.
Remove the opt.lg_prof_tcmax option and hard-code a cache size of 1024.
This setting is something that users just shouldn't have to worry about.
If lock contention actually ends up being a problem, the simple solution
available to the user is to reduce sampling frequency.
Remove structure magic, because 1) it is no longer conditional, and 2)
it stopped being very effective at detecting memory corruption several
years ago.
Convert configuration-related cpp conditional logic to use static
constant variables, e.g.:
#ifdef JEMALLOC_DEBUG
[...]
#endif
becomes:
if (config_debug) {
[...]
}
The advantage is clearer, more concise code. The main disadvantage is
that data structures no longer have conditionally defined fields, so
they pay the cost of all fields regardless of whether they are used. In
practice, this is only a minor concern; config_stats will go away in an
upcoming change, and config_prof is the only other major feature that
depends on more than a few special-purpose fields.
Rewrite prof_alloc_prep() as a cpp macro, PROF_ALLOC_PREP(), in order to
remove any doubt as to whether an additional stack frame is created.
Prior to this change, it was assumed that inlining would reduce the
total number of frames in the backtrace, but in practice behavior wasn't
completely predictable.
Create imemalign() and call it from posix_memalign(), memalign(), and
valloc(), so that all entry points require the same number of stack
frames to be ignored during backtracing.
