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`tsd_get`/`tsd_set` took the tsd address as a plain `&tsd_tls` -- `thread_pointer + const_offset`, which the compiler treats as loop-invariant. Under whole-program LTO it is hoisted out of the inlined malloc/free and kept in a callee-saved register across a user-space context switch (swapcontext, boost::context fibers); resumed on a different OS thread, the cached tsd/tcache still belongs to the previous thread and the two race -- heap corruption that reproduces only under LTO and is invisible to sanitizers. The write side is worse: tsd_set (from tsd_fetch_slow, on a thread's first allocation after migration) would copy the new thread's tsd over the previous thread's live one and register the wrong cleanup key. Route tsd_get/tsd_set in every GNU backend through JEMALLOC_TLS_ADDR(tsd_tls): a per-variable accessor that takes the address inside a noinline `memory`-barrier function, opaque to the optimizer. Correct for every TLS model, one call per access; MSVC keeps the plain address. The accessor is declared in every TU (JEMALLOC_TLS_ADDR_DECLARE) but defined once in src/tsd.c (JEMALLOC_TLS_ADDR_DEFINE, under JEMALLOC_TSD_C_): a per-TU `static` body is emitted at -O0 even when unused, pulling an undefined reference to the internal thread-local into the integration-test util objects, which link only the public shared library. DECLARE/DEFINE are invoked directly, never forwarded, so `##tlsvar` pastes the literal name rather than the expanded `je_tsd_tls`. |
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jemalloc is a general purpose malloc(3) implementation that emphasizes fragmentation avoidance and scalable concurrency support. jemalloc first came into use as the FreeBSD libc allocator in 2005, and since then it has found its way into numerous applications that rely on its predictable behavior. In 2010 jemalloc development efforts broadened to include developer support features such as heap profiling and extensive monitoring/tuning hooks. Modern jemalloc releases continue to be integrated back into FreeBSD, and therefore versatility remains critical. Ongoing development efforts trend toward making jemalloc among the best allocators for a broad range of demanding applications, and eliminating/mitigating weaknesses that have practical repercussions for real world applications. The COPYING file contains copyright and licensing information. The INSTALL file contains information on how to configure, build, and install jemalloc. The ChangeLog file contains a brief summary of changes for each release. URL: https://jemalloc.net/