Bug 832067 - Discard cached statements in healthreporter. r=gps

services/healthreport/healthreporter.jsm

@@ -307,6 +307,9 @@ HealthReporter.prototype = Object.freeze({
     this._log.info("HealthReporter started.");
     this._initialized = true;
     Services.obs.addObserver(this, "idle-daily", false);
+
+    // Clean up caches and reduce memory usage.
+    this._storage.compact();
     this._initializedDeferred.resolve(this);
   },
 
@@ -695,6 +698,7 @@ HealthReporter.prototype = Object.freeze({
       o.errors = errors;
     }
 
+    this._storage.compact();
     throw new Task.Result(JSON.stringify(o));
   },
 

services/metrics/storage.jsm

@@ -1204,6 +1204,21 @@ MetricsStorageSqliteBackend.prototype = Object.freeze({
     });
   },
 
+  /**
+   * Reduce memory usage as much as possible.
+   *
+   * This returns a promise that will be resolved on completion.
+   *
+   * @return Promise<>
+   */
+  compact: function () {
+    let self = this;
+    return this.enqueueOperation(function doCompact() {
+      self._connection.discardCachedStatements();
+      return self._connection.shrinkMemory();
+    });
+  },
+
   /**
    * Ensure a field ID matches a specified type.
    *