Calculate a process's Virtual Size including mapped, reserved and unused address space.
VSZ (Virtual Size) is the total virtual address space a process has mapped, regardless of whether pages are resident in RAM, swapped out, or never yet accessed. It includes code, heap, stacks, shared libraries, memory-mapped files, and reserved-but-unused regions. A large VSZ does not mean the process is consuming that much physical memory — only the RSS portion is resident.
Virtual size
VSZ = code + heap + stack + shared_libs + mmap_files + reserved
The JVM reserves its maximum heap size (-Xmx) upfront in the virtual address space even if only a fraction is actually used. This inflates VSZ but does not consume physical RAM until pages are actually touched.
Usually not. On 64-bit systems the virtual address space is vast (128TB+). VSZ only becomes a concern if it approaches the per-process RLIMIT_AS limit or if you're running on a 32-bit system with limited address space.