diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/GremlinAPI.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/GremlinAPI.java
index ae1efa1599..3973f4d1eb 100644
--- a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/GremlinAPI.java
+++ b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/GremlinAPI.java
@@ -38,12 +38,19 @@
 import com.baidu.hugegraph.api.filter.CompressInterceptor.Compress;
 import com.baidu.hugegraph.config.HugeConfig;
 import com.baidu.hugegraph.config.ServerOptions;
+import com.baidu.hugegraph.metric.MetricsUtil;
+import com.codahale.metrics.Histogram;
 import com.codahale.metrics.annotation.Timed;
 
 @Path("gremlin")
 @Singleton
 public class GremlinAPI extends API {
 
+    private static final Histogram gremlinInputHistogram =
+            MetricsUtil.registerHistogram(GremlinAPI.class, "gremlin-input");
+    private static final Histogram gremlinOutputHistogram =
+            MetricsUtil.registerHistogram(GremlinAPI.class, "gremlin-output");
+
     private Client client = ClientBuilder.newClient();
 
     private Response doGetRequest(String location, String auth, String query) {
@@ -60,10 +67,12 @@ private Response doGetRequest(String location, String auth, String query) {
             r.getHeaders().putSingle(HttpHeaders.CONTENT_TYPE,
                                      r.getMediaType().withCharset(CHARSET));
         }
+        gremlinInputHistogram.update(query.length());
+        gremlinOutputHistogram.update(r.getLength());
         return r;
     }
 
-    private Response doPostRequest(String location, String auth, Object req) {
+    private Response doPostRequest(String location, String auth, String req) {
         Entity<?> body = Entity.entity(req, MediaType.APPLICATION_JSON);
         Response r = this.client.target(location)
                                 .request()
@@ -77,6 +86,8 @@ private Response doPostRequest(String location, String auth, Object req) {
             r.getHeaders().putSingle(HttpHeaders.CONTENT_TYPE,
                                      r.getMediaType().withCharset(CHARSET));
         }
+        gremlinInputHistogram.update(req.length());
+        gremlinOutputHistogram.update(r.getLength());
         return r;
     }
 
diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/job/GremlinAPI.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/job/GremlinAPI.java
index bd8dec7687..45ec879118 100644
--- a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/job/GremlinAPI.java
+++ b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/job/GremlinAPI.java
@@ -41,11 +41,13 @@
 import com.baidu.hugegraph.core.GraphManager;
 import com.baidu.hugegraph.job.Job;
 import com.baidu.hugegraph.job.JobBuilder;
+import com.baidu.hugegraph.metric.MetricsUtil;
 import com.baidu.hugegraph.server.RestServer;
 import com.baidu.hugegraph.traversal.optimize.HugeScriptTraversal;
 import com.baidu.hugegraph.util.E;
 import com.baidu.hugegraph.util.JsonUtil;
 import com.baidu.hugegraph.util.Log;
+import com.codahale.metrics.Histogram;
 import com.codahale.metrics.annotation.Timed;
 
 import jersey.repackaged.com.google.common.collect.ImmutableMap;
@@ -56,6 +58,9 @@ public class GremlinAPI extends API {
 
     private static final Logger LOG = Log.logger(RestServer.class);
 
+    private static final Histogram gremlinJobInputHistogram =
+            MetricsUtil.registerHistogram(GremlinAPI.class, "gremlin-input");
+
     @POST
     @Timed
     @Status(Status.CREATED)
@@ -66,6 +71,7 @@ public Map<String, Id> post(@Context GraphManager manager,
                                 GremlinRequest request) {
         LOG.debug("Graph [{}] schedule gremlin job: {}", graph, request);
         checkCreatingBody(request);
+        gremlinJobInputHistogram.update(request.gremlin.length());
 
         HugeGraph g = graph(manager, graph);
         request.aliase(graph, "graph");
diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/core/GraphManager.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/core/GraphManager.java
index 2b39c45ff6..da7e5bce0d 100644
--- a/hugegraph-api/src/main/java/com/baidu/hugegraph/core/GraphManager.java
+++ b/hugegraph-api/src/main/java/com/baidu/hugegraph/core/GraphManager.java
@@ -193,9 +193,9 @@ private void checkBackendVersionOrExit() {
     }
 
     private void addMetrics(HugeConfig config) {
-        final MetricManager metrics = MetricManager.INSTANCE;
+        final MetricManager metric = MetricManager.INSTANCE;
         // Force to add server reporter
-        ServerReporter reporter = ServerReporter.instance(metrics.getRegistry());
+        ServerReporter reporter = ServerReporter.instance(metric.getRegistry());
         reporter.start(60L, TimeUnit.SECONDS);
 
         // Add metrics for MAX_WRITE_THREADS
diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/metric/SystemMetrics.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/metric/SystemMetrics.java
index faf0a760b0..161a041373 100644
--- a/hugegraph-api/src/main/java/com/baidu/hugegraph/metric/SystemMetrics.java
+++ b/hugegraph-api/src/main/java/com/baidu/hugegraph/metric/SystemMetrics.java
@@ -42,16 +42,25 @@ public Map<String, Map<String, Object>> metrics() {
         metrics.put("heap", this.getHeapMetrics());
         metrics.put("nonheap", this.getNonHeapMetrics());
         metrics.put("thread", this.getThreadMetrics());
-        metrics.put("class-loading", this.getClassLoadingMetrics());
-        metrics.put("garbage-collector", this.getGarbageCollectionMetrics());
+        metrics.put("class_loading", this.getClassLoadingMetrics());
+        metrics.put("garbage_collector", this.getGarbageCollectionMetrics());
         return metrics;
     }
 
     private Map<String, Object> getBasicMetrics() {
         Map<String, Object> metrics = new LinkedHashMap<>();
         Runtime runtime = Runtime.getRuntime();
-        metrics.put("mem", (runtime.totalMemory() + totalNonHeapMemory()) / MB);
-        metrics.put("mem_free", runtime.freeMemory() / MB);
+        // Heap allocated memory (measured in bytes)
+        long total = runtime.totalMemory();
+        // Heap free memory
+        long free = runtime.freeMemory();
+        long used = total - free;
+
+        metrics.put("mem", (total + totalNonHeapMemory()) / MB);
+        metrics.put("mem_total", total / MB);
+        metrics.put("mem_used", used / MB);
+        metrics.put("mem_free", free / MB);
+        metrics.put("mem_unit", "MB");
         metrics.put("processors", runtime.availableProcessors());
         metrics.put("uptime", ManagementFactory.getRuntimeMXBean().getUptime());
         metrics.put("systemload_average",
@@ -60,11 +69,12 @@ private Map<String, Object> getBasicMetrics() {
         return metrics;
     }
 
-    private long totalNonHeapMemory() {
+    private static long totalNonHeapMemory() {
         try {
             return ManagementFactory.getMemoryMXBean()
-                                    .getNonHeapMemoryUsage().getUsed();
-        } catch (Throwable ex) {
+                                    .getNonHeapMemoryUsage()
+                                    .getCommitted();
+        } catch (Throwable ignored) {
             return 0;
         }
     }