Promiseの闇？（再帰の闇かもしれない）

200万行近いShapefileがあるじゃろ？

Node.jsで処理しようと思えば、Shapefile モジュールを使うじゃろ？

で、単純に、サンプルに等しい処理をまわすと...

shapefile単純ぶんまわし

var shapefile = require("shapefile");

var count = 0;   
shapefile.open("example.shp")
    .then(source => source.read()
    .then(function log(result) {
      if (result.done) return;
      count = count + 1;
      if (count % 10000 == 0) console.log(count); 
      return source.read().then(log);
    }))
  .catch(error => console.error(error.stack));

160万行目くらいで、こうじゃ！

Windowsコマンドプロンプト

<--- Last few GCs --->

 1775279 ms: Scavenge 1398.3 (1458.1) -> 1398.3 (1458.1) MB, 0.3 / 0 ms (+ 0.0 m
s in 1 steps since last GC) [allocation failure] [incremental marking delaying m
ark-sweep].
 1776507 ms: Mark-sweep 1398.3 (1458.1) -> 1398.3 (1458.1) MB, 1227.5 / 0 ms (+
0.0 ms in 2 steps since start of marking, biggest step 0.0 ms) [last resort gc].

 1777674 ms: Mark-sweep 1398.3 (1458.1) -> 1398.3 (1458.1) MB, 1178.9 / 0 ms [la
st resort gc].


<--- JS stacktrace --->

==== JS stack trace =========================================

Security context: 00000114947E3AD1 <JS Object>
    2: decode [D:\Works\XXXXXX XXX\XXXX\node_modules\text-encoding\lib\encoding.
js:1128] [pc=00000318CB0F1257] (this=0000024543C241C9 <a TextDecoder with map 00
0001CBC3223059>,input=0000015E2DF8DE69 <an Uint8Array with map 0000035139609CC9>
,options=0000015E2DF8DE31 <an Object with map 00000351396095E9>)
    3: arguments adaptor frame: 1->2
    7: _decode [native v8natives.js:1213] [pc=0000031...

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - process out of memory

これ以上は知識なさ過ぎて、Promiseネストか再帰ネストかどっちが問題なんかようわからへんけど、160万階層もネストすればまあ何かしら問題あるんやろなあ...