577d4572b0
Rather than protecting dss operations with a mutex, use atomic operations. This has negligible impact on synchronization overhead during typical dss allocation, but is a substantial improvement for extent_in_dss() and the newly added extent_dss_mergeable(), which can be called multiple times during extent deallocations. This change also has the advantage of avoiding tsd in deallocation paths associated with purging, which resolves potential deadlocks during thread exit due to attempted tsd resurrection. This resolves #425.
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/