this fixes https://github.com/gorhill/uMatrix/issues/144

platform/chromium/vapi-client.js

@@ -150,6 +150,9 @@ vAPI.messaging = {
             },
             close: function() {
                 delete vAPI.messaging.channels[this.channelName];
+                if ( Object.keys(vAPI.messaging.channels).length === 0 ) {
+                    vAPI.messaging.close();
+                }
             }
         };
 

src/js/contentscript-end.js

@@ -56,10 +56,36 @@ if ( vAPI.contentscriptEndInjected ) {
 }
 vAPI.contentscriptEndInjected = true;
 
+/******************************************************************************/
+/******************************************************************************/
+
+var shutdownJobs = (function() {
+    var jobs = [];
+
+    return {
+        add: function(job) {
+            jobs.push(job);
+        },
+        exec: function() {
+            //console.debug('Shutting down...');
+            var job;
+            while ( job = jobs.pop() ) {
+                job();
+            }
+        }
+    };
+})();
+
+/******************************************************************************/
 /******************************************************************************/
 
 var messager = vAPI.messaging.channel('contentscript-end.js');
 
+// https://github.com/gorhill/uMatrix/issues/144
+shutdownJobs.add(function() {
+    messager.close();
+});
+
 /******************************************************************************/
 
 // https://github.com/chrisaljoudi/uBlock/issues/789
@@ -119,7 +145,14 @@ var uBlockCollapser = (function() {
         this.collapse = false;
     };
 
-    var onProcessed = function(requests) {
+    var onProcessed = function(response) {
+        // https://github.com/gorhill/uMatrix/issues/144
+        if ( response.shutdown ) {
+            shutdownJobs.exec();
+            return;
+        }
+
+        var requests = response.result;
         if ( requests === null || Array.isArray(requests) === false ) {
             return;
         }
@@ -314,24 +347,32 @@ var uBlockCollapser = (function() {
         firstRetrieveHandler = null;
 
         // These are sent only once
-        if ( response ) {
+        var result = response && response.result;
-            if ( response.highGenerics ) {
+        if ( result ) {
-                highGenerics = response.highGenerics;
+            if ( result.highGenerics ) {
+                highGenerics = result.highGenerics;
             }
-            if ( response.donthide ) {
+            if ( result.donthide ) {
-                processLowGenerics(response.donthide, nullArray);
+                processLowGenerics(result.donthide, nullArray);
             }
         }
 
         nextRetrieveHandler(response);
     };
 
-    var nextRetrieveHandler = function(selectors) {
+    var nextRetrieveHandler = function(response) {
+        // https://github.com/gorhill/uMatrix/issues/144
+        if ( response && response.shutdown ) {
+            shutdownJobs.exec();
+            return;
+        }
+
         //var tStart = timer.now();
         //console.debug('µBlock> contextNodes = %o', contextNodes);
+        var result = response && response.result;
         var hideSelectors = [];
-        if ( selectors && selectors.hide.length ) {
+        if ( result && result.hide.length ) {
-            processLowGenerics(selectors.hide, hideSelectors);
+            processLowGenerics(result.hide, hideSelectors);
         }
         if ( highGenerics ) {
             if ( highGenerics.hideLowCount ) {
@@ -688,6 +729,14 @@ var uBlockCollapser = (function() {
         childList: true,
         subtree: true
     });
+
+    // https://github.com/gorhill/uMatrix/issues/144
+    shutdownJobs.add(function() {
+        treeObserver.disconnect();
+        if ( addedNodeListsTimer !== null ) {
+            clearTimeout(addedNodeListsTimer);
+        }
+    });
 })();
 
 /******************************************************************************/
@@ -700,12 +749,19 @@ var uBlockCollapser = (function() {
 // - Elements dynamically added to the page
 // - Elements which resource URL changes
 
-var onResourceFailed = function(ev) {
+(function() {
+    var onResourceFailed = function(ev) {
         //console.debug('onResourceFailed(%o)', ev);
         uBlockCollapser.add(ev.target);
         uBlockCollapser.process();
-};
+    };
-document.addEventListener('error', onResourceFailed, true);
+    document.addEventListener('error', onResourceFailed, true);
+
+    // https://github.com/gorhill/uMatrix/issues/144
+    shutdownJobs.add(function() {
+        document.removeEventListener('error', onResourceFailed, true);
+    });
+})();
 
 /******************************************************************************/
 /******************************************************************************/
@@ -764,6 +820,11 @@ document.addEventListener('error', onResourceFailed, true);
     };
 
     window.addEventListener('contextmenu', onContextMenu, true);
+
+    // https://github.com/gorhill/uMatrix/issues/144
+    shutdownJobs.add(function() {
+        document.removeEventListener('contextmenu', onContextMenu, true);
+    });
 })();
 
 /******************************************************************************/

src/js/messaging.js

@@ -496,9 +496,12 @@ var onMessage = function(details, sender, callback) {
 
     switch ( details.what ) {
         case 'retrieveGenericCosmeticSelectors':
-            if ( pageStore && pageStore.getGenericCosmeticFilteringSwitch()
+            response = {
-                && (!frameStore || frameStore.getNetFilteringSwitch()) ) {
+                shutdown: !pageStore || !pageStore.getNetFilteringSwitch() || (frameStore && !frameStore.getNetFilteringSwitch()),
-                response = µb.cosmeticFilteringEngine.retrieveGenericSelectors(details);
+                result: null
+            };
+            if(pageStore && pageStore.getGenericCosmeticFilteringSwitch()) {
+                response.result = µb.cosmeticFilteringEngine.retrieveGenericSelectors(details);
             }
             break;
 
@@ -508,7 +511,13 @@ var onMessage = function(details, sender, callback) {
 
         // Evaluate many requests
         case 'filterRequests':
-            response = filterRequests(pageStore, details);
+            response = {
+                shutdown: !pageStore || !pageStore.getNetFilteringSwitch(),
+                result: null
+            };
+            if(pageStore) {
+                response.result = filterRequests(pageStore, details);
+            }
             break;
 
         default: