Update:

Development of Jemalloc will transition back to the original open source
project: https://github.com/jemalloc/jemalloc. Meta’s fork of the Jemalloc
project will be fully archived as part of the transition. We look forward
to continuing the collaboration with the community to drive jemalloc.

See blog post for details:
https://engineering.fb.com/2026/03/02/data-infrastructure/investing-in-infrastructure-metas-renewed-commitment-to-jemalloc/

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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/