Major Bug in glibc is Killing Applications With a Memory Limit
malloc() preallocates large chunks of memory, per thread. This is meant as a performance optimization, to reduce memory contention in highly threaded applications. On a typical physical server, dual Xeon CPU with a terabyte of RAM. The core count is easily 40 or above. 10 cores * 2 CPU * 2 for hyper threading. This means a preallocation of up to 20 GB of RAM in the process.