added workaround to mapnik-node memory leak (see mapnik/node-mapnik#950)

FreemapSlovakia · Jul 6, 2020 · 4f07d96 · 4f07d96
1 parent c577304
commit 4f07d96
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Showing 3 changed files with 44 additions and 13 deletions.
diff --git a/lib/httpServer.js b/lib/httpServer.js
@@ -41,6 +41,10 @@ const mimeType = config.get('format.mimeType');
 let generateMapnikConfig;
 let mapFeatureProperties;
 
+const white = new mapnik.Color('white');
+
+const images = new Map();
+
 router.get('/:zz/:xx/:yy', async (ctx) => {
   const { zz, xx, yy } = ctx.params;
 
@@ -74,11 +78,15 @@ router.get('/:zz/:xx/:yy', async (ctx) => {
 
     ctx.type = 'image/png';
 
-    const im = new mapnik.Image(256 * scale, 256 * scale);
+    let body = images.get(scale);
 
-    await im.fill(new mapnik.Color('white'));
+    if (!body) {
+      const im = new mapnik.Image(256 * scale, 256 * scale);
+      await im.fill(white);
+      images.set(scale, await im.encodeAsync('png8:c=1:t=0'));
+    }
 
-    ctx.body = await im.encodeAsync('png8:c=1:t=0');
+    ctx.body = body;
 
     // white 1x1
     // ctx.body = Buffer.from('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAwMCAO+ip1sAAAAASUVORK5CYII=', 'base64');

diff --git a/lib/mapnikPool.js b/lib/mapnikPool.js
@@ -1,6 +1,5 @@
 const { promisify } = require('util');
 const { cpus } = require('os');
-const process = require('process');
 
 const mapnik = require('mapnik');
 const config = require('config');
@@ -38,17 +37,38 @@ function initPool(mapnikConfig) {
     mapnik.Image.prototype.demultiply,
   );
 
+  mapnik.Image.prototype.resizeAsync = promisify(mapnik.Image.prototype.resize);
+
   mapnik.Image.prototype.fillAsync = promisify(mapnik.Image.prototype.fill);
 
   mapnik.Image.prototype.filterAsync = promisify(mapnik.Image.prototype.filter);
 
+  mapnik.Image.prototype.clearAsync = promisify(mapnik.Image.prototype.clear);
+
   const nCpus = cpus().length;
 
   const factory = {
     async create() {
       const map = new mapnik.Map(256, 256);
       await map.fromStringAsync(mapnikConfig);
-      return { map, useCount: 0 };
+      let images = new Map();
+
+      return {
+        map,
+        useCount: 0,
+        async getImage(key, scale) {
+          let im = images.get(key);
+
+          if (!im) {
+            im = new mapnik.Image(256 * scale, 256 * scale);
+            images.set(scale, im);
+          } else {
+            await im.clearAsync();
+          }
+
+          return im;
+        },
+      };
     },
 
     async destroy() {

diff --git a/lib/renderrer.js b/lib/renderrer.js
@@ -28,6 +28,8 @@ module.exports = { renderTile, exportMap };
 
 mapnik.registerFonts(config.get('dirs.fonts'), { recurse: true });
 
+const white = new mapnik.Color('white');
+
 let cnt = 0;
 
 // TODO if out of prerender area and reqScale is provided then render only that scale
@@ -89,16 +91,16 @@ async function renderSingleScale(p, zoom, x, y, scale, prerender) {
   } tile ${spec}: `;
 
   if (prerender) {
-    const a = dirtyTiles.get(tile2key({ zoom, x, y }));
-    if (!a) {
+    const dirtyTile = dirtyTiles.get(tile2key({ zoom, x, y }));
+    if (!dirtyTile) {
       console.warn(`${logPrefix}no dirty meta found`);
       return;
     }
 
     try {
       const { mtimeMs } = await stat(`${ps}.${extension}`);
       if (
-        mtimeMs > a.dt &&
+        mtimeMs > dirtyTile.dt &&
         (!rerenderOlderThanMs || mtimeMs > rerenderOlderThanMs)
       ) {
         console.log(`${logPrefix}fresh`);
@@ -111,10 +113,10 @@ async function renderSingleScale(p, zoom, x, y, scale, prerender) {
 
   console.log(`${logPrefix}rendering`);
 
-  let im = new mapnik.Image(256 * scale, 256 * scale);
-
   const maps = await getPool().acquire(prerender ? 1 : 0);
-  const { map } = maps;
+  const { map, getImage } = maps;
+
+  let im = await getImage('main', scale);
 
   /** @type number */
   let t;
@@ -138,8 +140,9 @@ async function renderSingleScale(p, zoom, x, y, scale, prerender) {
     measure('render', Date.now() - t);
 
     // this is to get rid of transparency because of edge blurring and JPEG
-    const bgIm = new mapnik.Image(256 * scale, 256 * scale);
-    await bgIm.fill(new mapnik.Color('white'));
+
+    const bgIm = await getImage('bg', scale);
+    await bgIm.fill(white);
     await bgIm.premultiplyAsync();
     await im.premultiplyAsync();
     // dst.compositeAsync(src