The change to make freelists a runtime option (https://github.com/apache/trafficserver/commit/e56d1f9eb6f55b0257d1fb758b773dea468159ee) seems to have missed this file.
With the preprocessor symbol TS_USE_FREELIST now gone (earlier used to be 1), the overload of thread_alloc defined in this file always uses Proxy Allocator (the second argument to the method) but free routines are from the freelist. This overload of thread_alloc is used by HdrHeap, that is widely used in transaction processing, causing leaks.
Steps to reproduce:
Traffic server with a single remap configuration, and ab workload should show memory growth.
Version seen in: Traffic Server built from branches master, 6.1.x, 6.2.x.
Platform: Linux 64-bit (RHEL 6.6), g++ 4.4.7