$ time ./llil4map long* long* long* | cksum
llil4map start
use OpenMP             ( old )     ( new )
memory consumption     36.6 GB     17.5 GB
use boost sort
get properties         12.967s     11.836s
map to vector           3.244s      1.292s
vector stable sort     10.265s     11.025s
write stdout            1.410s      1.364s
total time             27.887s     25.519s
    count lines      970195200
    count unique     295755152
29612263 5038456270

       real time     0m43.973s   0m27.461s
       user         25m08.532s  20m02.479s
       sys           0m55.602s   0m43.250s

##</code><code>##

$ time ./llil4vec long* long* long* | cksum
llil4vec start
use OpenMP             ( old )    (mem-fix)    ( new )
memory consumption     89.6 GB     62.4 GB     33.0 GB
use boost sort
get properties         48.133s     32.659s     12.993s
sort properties        39.684s     39.399s     33.421s
vector reduce          87.982s     75.644s     35.568s
vector stable sort     25.990s     31.133s     21.987s
write stdout            3.707s      3.206s      3.693s
total time            205.498s    182.042s    107.664s
    count lines      970195200
    count unique     295755152
29612263 5038456270

       real time     3m57.228s   3m38.118s   1m50.092s
       user         73m27.931s  70m13.776s  45m32.094s
       sys           2m42.941s   2m29.584s   2m20.917s

##</code><code>##

#pragma omp parallel for schedule(static, 1) reduction(+:num_lines)
for (int i = 0; i < nfiles; ++i) {
   vec_str_int_type locvec;
   num_lines += get_properties(fname[i], locvec);
   #pragma omp critical
   {
      // Append local vector to propvec (consumes more memory)
      // propvec.insert(
      //    propvec.end(),
      //    std::make_move_iterator(locvec.begin()),
      //    std::make_move_iterator(locvec.end())
      // );

      // Append local vector to propvec (faster)
      auto it  = locvec.begin();
      auto it2 = locvec.end();
      for (; it != it2; ++it)
         propvec.emplace_back(std::move(*it));
   }
}

##</code><code>##

// Reduce a vector range (tally adjacent count fields of duplicate key names)
static void reduce_vec(auto& vec)  
{  
   if (vec.size() > 0) { 
      auto it1 = vec.begin(); auto itr = it1; auto itw = it1;
      auto it2 = vec.end();
      auto curr = itr;

      for (++itr; itr != it2; ++itr) {
         if (itr->first == curr->first) {
            curr->second += itr->second;
         }
         else {
            if (itw != curr)
               *itw = std::move(*curr);
            ++itw;
            curr = itr;
         }
      }

      if (itw != curr)
         *itw = std::move(*curr);
   
      vec.resize(std::distance(it1, ++itw));
   }
}  

##</code><code>##

string_cnt.h   - original + key length stored with count
string_cnt_f.h - fixed-length-only version
string_cnt_u.h - union std::array

##</code><code>##

   // Free dynamically allocated memory in parallel.
#ifndef FIXED_LENGTH_ONLY
   #pragma omp parallel for schedule(dynamic, 300000) num_threads(nthds)
   for (size_t i = 0; i < propvec.size(); i++)
      propvec[i].free();
#endif