final JvmObj jvmObj = new JvmObj();
        final JvmStats jvmStats = JvmStats.jvmStats();
        final Mem mem = jvmStats.getMem();
        final JvmMemoryObj jvmMemoryObj = new JvmMemoryObj();
        jvmObj.memory = jvmMemoryObj;
        final JvmMemoryHeapObj jvmMemoryHeapObj = new JvmMemoryHeapObj();
        jvmMemoryObj.heap = jvmMemoryHeapObj;
        jvmMemoryHeapObj.used = mem.getHeapUsed().getBytes();

        buf.append("},");
        buf.append("\"virtual_memory\":{");
        append(buf, "total", () -> processProbe.getTotalVirtualMemorySize());
        buf.append('}');
        buf.append("},");
    }

    private void appendOsStats(final StringBuilder buf) {
        buf.append("\"os\":{");
        final OsProbe osProbe = OsProbe.getInstance();
        buf.append("\"memory\":{");
        buf.append("\"physical\":{");