Reduce memory footprint (#711)

CHANGELOG.yaml

@@ -1,4 +1,6 @@
 unreleased:
+  fixed bugs:
+    - GH-711 Fixed an issue where boot code was not being garbage collected
   chores:
     - GH-710 Refactor worker interface to be node alike
 

lib/bridge.js

@@ -67,6 +67,7 @@ module.exports = function (bridge, options, callback) {
         firmwareCode;
 
     const id = UVM_ID_ + randomNumber(),
+        { bootCode, debug, bootTimeout, _sandbox } = options,
 
         // function to forward messages emitted
         forwardEmits = (e) => {
@@ -105,7 +106,7 @@ module.exports = function (bridge, options, callback) {
             worker.off(EXIT, forwardExit);
 
 
-            (options._sandbox ? Promise.resolve() : worker.terminate())
+            (_sandbox ? Promise.resolve() : worker.terminate())
                 .then(() => { callback(); });
             worker = null;
         };
@@ -131,18 +132,18 @@ module.exports = function (bridge, options, callback) {
     });
 
     // get firmware code string with boot code
-    firmwareCode = sandboxFirmware(options.bootCode, id, options.debug);
+    firmwareCode = sandboxFirmware(bootCode, id, debug);
 
     // start boot timer, stops once we get the load signal, terminate otherwise
     bootTimer = setTimeout(() => {
         terminateWorker();
-        callback(new Error(`uvm: boot timed out after ${options.bootTimeout}ms.`));
-    }, options.bootTimeout);
+        callback(new Error(`uvm: boot timed out after ${bootTimeout}ms.`));
+    }, bootTimeout);
 
     // if sandbox worker is provided, we simply need to init with firmware code
     // @todo validate sandbox type or APIs
-    if (options._sandbox) {
-        worker = options._sandbox;
+    if (_sandbox) {
+        worker = _sandbox;
 
         // add event listener methods for Web worker
         /* istanbul ignore next-line */

test/benchmark/memory-footprint.test.js

@@ -0,0 +1,10 @@
+
+// TODO: Implement this test
+// v8.getHeapStatistics() can be used to measure memory
+// footprint but the results from it are not consistent with
+// values from heap snapshots created manually in Chrome DevTools.
+describe.skip('memory footprint', function () {
+    it('should not increase memory footprint significantly', function (done) {
+        done();
+    });
+});