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The bug is subtle but critical: if application performs the following three actions in sequence: (a) turn `prof_active` off, (b) make at least one allocation that triggers the malloc slow path via the `if (unlikely(bytes_until_sample < 0))` path, and (c) turn `prof_active` back on, then the application would never get another sample (until a very very long time later). The fix is to properly reset `bytes_until_sample` rather than throwing it all the way to `SSIZE_MAX`. A side minor change is to call `prof_active_get_unlocked()` rather than directly grabbing the `prof_active` variable - it is the very reason why we defined the `prof_active_get_unlocked()` function.
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: http://jemalloc.net/