AMBARI-3707. YARN dynamic configs generate 0 map/reduce memory on 2GB machines. (srimanth)

ambari-web/app/utils/configs/defaults_providers/yarn_defaults_provider.js

@@ -101,6 +101,9 @@ App.YARNDefaultsProvider = App.DefaultsProvider.create({
     if (this.get('clusterData.hBaseInstalled')) {
       ram -= this.get('hBaseRam')
     }
+    if (ram < 1) {
+      ram = 1;
+    }
     ram *= this.get('GB');
     ram /= containerSize;
     return Math.round(Math.max(cpu, Math.min(disk, ram)));
@@ -119,6 +122,9 @@ App.YARNDefaultsProvider = App.DefaultsProvider.create({
     if (this.get('clusterData.hBaseInstalled')) {
       ram -= this.get('hBaseRam')
     }
+    if (ram < 1) {
+      ram = 1;
+    }
     ram *= this.get('GB');
     var container_ram = Math.abs(ram / containers);
     return container_ram > this.get('GB') ? container_ram / (512 * 512) : container_ram;