Merge pull request #947 from lcybo/master

修复group模式报错

deployer/src/main/resources/metrics/Canal_instances_tmpl.json

@@ -1,4 +1,34 @@
 {
+  "__inputs": [
+    {
+      "name": "DS_PROMETHEUS",
+      "label": "prometheus",
+      "description": "",
+      "type": "datasource",
+      "pluginId": "prometheus",
+      "pluginName": "Prometheus"
+    }
+  ],
+  "__requires": [
+    {
+      "type": "grafana",
+      "id": "grafana",
+      "name": "Grafana",
+      "version": "5.2.2"
+    },
+    {
+      "type": "panel",
+      "id": "graph",
+      "name": "Graph",
+      "version": "5.0.0"
+    },
+    {
+      "type": "datasource",
+      "id": "prometheus",
+      "name": "Prometheus",
+      "version": "5.0.0"
+    }
+  ],
   "annotations": {
     "list": [
       {
@@ -15,8 +45,8 @@
   "editable": true,
   "gnetId": null,
   "graphTooltip": 0,
-  "id": 8,
+  "id": null,
-  "iteration": 1534740332233,
+  "iteration": 1536989235272,
   "links": [],
   "panels": [
     {
@@ -189,7 +219,7 @@
       "steppedLine": false,
       "targets": [
         {
-          "expr": "rate(canal_instance_received_binlog_bytes{destination=~\"$destination\"}[2m]) / 1024",
+          "expr": "rate(canal_instance_received_binlog_bytes{destination=~\"$destination\", parser=\"0\"}[2m]) / 1024",
           "format": "time_series",
           "interval": "15s",
           "intervalFactor": 2,
@@ -203,6 +233,22 @@
           "intervalFactor": 2,
           "legendFormat": "outbound",
           "refId": "B"
+        },
+        {
+          "expr": "rate(canal_instance_received_binlog_bytes{destination=~\"$destination\", parser=\"1\"}[2m]) / 1024",
+          "format": "time_series",
+          "interval": "15s",
+          "intervalFactor": 2,
+          "legendFormat": "inbound-1",
+          "refId": "C"
+        },
+        {
+          "expr": "rate(canal_instance_received_binlog_bytes{destination=~\"$destination\", parser=\"2\"}[2m]) / 1024",
+          "format": "time_series",
+          "interval": "15s",
+          "intervalFactor": 2,
+          "legendFormat": "inbound-2",
+          "refId": "D"
         }
       ],
       "thresholds": [],
@@ -399,20 +445,36 @@
       "steppedLine": false,
       "targets": [
         {
-          "expr": "clamp_max(rate(canal_instance_sink_blocking_time{destination=~\"$destination\"}[2m]), 1000) / 10",
+          "expr": "clamp_max(rate(canal_instance_publish_blocking_time{destination=~\"$destination\", parser=\"0\"}[2m]), 1000) / 10",
           "format": "time_series",
           "interval": "15s",
           "intervalFactor": 2,
           "legendFormat": "dump",
-          "refId": "A"
+          "refId": "B"
         },
         {
-          "expr": "clamp_max(rate(canal_instance_publish_blocking_time{destination=~\"$destination\"}[2m]), 1000) / 10",
+          "expr": "clamp_max(rate(canal_instance_sink_blocking_time{destination=~\"$destination\"}[2m]), 1000) / 10",
           "format": "time_series",
           "interval": "15s",
           "intervalFactor": 2,
           "legendFormat": "sink",
-          "refId": "B"
+          "refId": "A"
+        },
+        {
+          "expr": "clamp_max(rate(canal_instance_publish_blocking_time{destination=~\"$destination\", parser=\"1\"}[2m]), 1000) / 10",
+          "format": "time_series",
+          "interval": "15s",
+          "intervalFactor": 2,
+          "legendFormat": "dump-1",
+          "refId": "C"
+        },
+        {
+          "expr": "clamp_max(rate(canal_instance_publish_blocking_time{destination=~\"$destination\", parser=\"2\"}[2m]), 1000) / 10",
+          "format": "time_series",
+          "interval": "15s",
+          "intervalFactor": 2,
+          "legendFormat": "dump-2",
+          "refId": "D"
         }
       ],
       "thresholds": [],
@@ -465,7 +527,7 @@
       },
       "id": 32,
       "panels": [],
-      "title": "Server",
+      "title": "Throughput",
       "type": "row"
     },
     {
@@ -660,180 +722,6 @@
         "alignLevel": null
       }
     },
-    {
-      "aliasColors": {},
-      "bars": false,
-      "dashLength": 10,
-      "dashes": false,
-      "datasource": "$datasource",
-      "description": "Canal instance ringbuffer内未释放的events数量。",
-      "fill": 1,
-      "gridPos": {
-        "h": 5,
-        "w": 6,
-        "x": 12,
-        "y": 7
-      },
-      "id": 20,
-      "legend": {
-        "avg": false,
-        "current": false,
-        "max": false,
-        "min": false,
-        "show": true,
-        "total": false,
-        "values": false
-      },
-      "lines": true,
-      "linewidth": 1,
-      "links": [],
-      "nullPointMode": "null",
-      "percentage": false,
-      "pointradius": 5,
-      "points": false,
-      "renderer": "flot",
-      "seriesOverrides": [],
-      "spaceLength": 10,
-      "stack": false,
-      "steppedLine": false,
-      "targets": [
-        {
-          "expr": "canal_instance_store_produce_seq{destination=~\"$destination\"} - canal_instance_store_consume_seq{destination=~\"$destination\"}",
-          "format": "time_series",
-          "interval": "15s",
-          "intervalFactor": 2,
-          "legendFormat": "events",
-          "refId": "A"
-        }
-      ],
-      "thresholds": [],
-      "timeFrom": null,
-      "timeShift": null,
-      "title": "Store remain events",
-      "tooltip": {
-        "shared": true,
-        "sort": 0,
-        "value_type": "individual"
-      },
-      "type": "graph",
-      "xaxis": {
-        "buckets": null,
-        "mode": "time",
-        "name": null,
-        "show": true,
-        "values": []
-      },
-      "yaxes": [
-        {
-          "decimals": null,
-          "format": "none",
-          "label": "",
-          "logBase": 1,
-          "max": null,
-          "min": null,
-          "show": true
-        },
-        {
-          "decimals": null,
-          "format": "short",
-          "label": null,
-          "logBase": 1,
-          "max": null,
-          "min": null,
-          "show": true
-        }
-      ],
-      "yaxis": {
-        "align": false,
-        "alignLevel": null
-      }
-    },
-    {
-      "aliasColors": {},
-      "bars": false,
-      "dashLength": 10,
-      "dashes": false,
-      "datasource": "$datasource",
-      "description": "Canal instance ringbuffer 内未释放events占用内存。",
-      "fill": 1,
-      "gridPos": {
-        "h": 5,
-        "w": 6,
-        "x": 18,
-        "y": 7
-      },
-      "id": 22,
-      "legend": {
-        "avg": false,
-        "current": false,
-        "max": false,
-        "min": false,
-        "show": true,
-        "total": false,
-        "values": false
-      },
-      "lines": true,
-      "linewidth": 1,
-      "links": [],
-      "nullPointMode": "null",
-      "percentage": false,
-      "pointradius": 5,
-      "points": false,
-      "renderer": "flot",
-      "seriesOverrides": [],
-      "spaceLength": 10,
-      "stack": false,
-      "steppedLine": false,
-      "targets": [
-        {
-          "expr": "(canal_instance_store_produce_mem{destination=~\"$destination\"} - canal_instance_store_consume_mem{destination=~\"$destination\"}) / 1024",
-          "format": "time_series",
-          "interval": "15s",
-          "intervalFactor": 2,
-          "legendFormat": "memsize",
-          "refId": "A"
-        }
-      ],
-      "thresholds": [],
-      "timeFrom": null,
-      "timeShift": null,
-      "title": "Store remain mem",
-      "tooltip": {
-        "shared": true,
-        "sort": 0,
-        "value_type": "individual"
-      },
-      "type": "graph",
-      "xaxis": {
-        "buckets": null,
-        "mode": "time",
-        "name": null,
-        "show": true,
-        "values": []
-      },
-      "yaxes": [
-        {
-          "format": "deckbytes",
-          "label": null,
-          "logBase": 1,
-          "max": null,
-          "min": null,
-          "show": true
-        },
-        {
-          "format": "short",
-          "label": null,
-          "logBase": 1,
-          "max": null,
-          "min": null,
-          "show": true
-        }
-      ],
-      "yaxis": {
-        "align": false,
-        "alignLevel": null
-      }
-    },
     {
       "collapsed": false,
       "gridPos": {
@@ -938,7 +826,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "$datasource",
+      "datasource": "${DS_PROMETHEUS}",
       "description": "client 请求的GET与ACK包的QPS。",
       "fill": 1,
       "gridPos": {
@@ -1218,6 +1106,193 @@
         "align": false,
         "alignLevel": null
       }
+    },
+    {
+      "collapsed": false,
+      "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": 18
+      },
+      "id": 36,
+      "panels": [],
+      "title": "Store",
+      "type": "row"
+    },
+    {
+      "aliasColors": {},
+      "bars": false,
+      "dashLength": 10,
+      "dashes": false,
+      "datasource": "$datasource",
+      "description": "Canal instance ringbuffer内未释放的events数量。",
+      "fill": 1,
+      "gridPos": {
+        "h": 5,
+        "w": 6,
+        "x": 0,
+        "y": 19
+      },
+      "id": 20,
+      "legend": {
+        "avg": false,
+        "current": false,
+        "max": false,
+        "min": false,
+        "show": true,
+        "total": false,
+        "values": false
+      },
+      "lines": true,
+      "linewidth": 1,
+      "links": [],
+      "nullPointMode": "null",
+      "percentage": false,
+      "pointradius": 5,
+      "points": false,
+      "renderer": "flot",
+      "seriesOverrides": [],
+      "spaceLength": 10,
+      "stack": false,
+      "steppedLine": false,
+      "targets": [
+        {
+          "expr": "canal_instance_store_produce_seq{destination=~\"$destination\"} - canal_instance_store_consume_seq{destination=~\"$destination\"}",
+          "format": "time_series",
+          "interval": "15s",
+          "intervalFactor": 2,
+          "legendFormat": "events",
+          "refId": "A"
+        }
+      ],
+      "thresholds": [],
+      "timeFrom": null,
+      "timeShift": null,
+      "title": "Store remain events",
+      "tooltip": {
+        "shared": true,
+        "sort": 0,
+        "value_type": "individual"
+      },
+      "type": "graph",
+      "xaxis": {
+        "buckets": null,
+        "mode": "time",
+        "name": null,
+        "show": true,
+        "values": []
+      },
+      "yaxes": [
+        {
+          "decimals": null,
+          "format": "none",
+          "label": "",
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        },
+        {
+          "decimals": null,
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        }
+      ],
+      "yaxis": {
+        "align": false,
+        "alignLevel": null
+      }
+    },
+    {
+      "aliasColors": {},
+      "bars": false,
+      "dashLength": 10,
+      "dashes": false,
+      "datasource": "$datasource",
+      "description": "Canal instance ringbuffer 内未释放events占用内存。",
+      "fill": 1,
+      "gridPos": {
+        "h": 5,
+        "w": 6,
+        "x": 6,
+        "y": 19
+      },
+      "id": 22,
+      "legend": {
+        "avg": false,
+        "current": false,
+        "max": false,
+        "min": false,
+        "show": true,
+        "total": false,
+        "values": false
+      },
+      "lines": true,
+      "linewidth": 1,
+      "links": [],
+      "nullPointMode": "null",
+      "percentage": false,
+      "pointradius": 5,
+      "points": false,
+      "renderer": "flot",
+      "seriesOverrides": [],
+      "spaceLength": 10,
+      "stack": false,
+      "steppedLine": false,
+      "targets": [
+        {
+          "expr": "(canal_instance_store_produce_mem{destination=~\"$destination\"} - canal_instance_store_consume_mem{destination=~\"$destination\"}) / 1024",
+          "format": "time_series",
+          "interval": "15s",
+          "intervalFactor": 2,
+          "legendFormat": "memsize",
+          "refId": "A"
+        }
+      ],
+      "thresholds": [],
+      "timeFrom": null,
+      "timeShift": null,
+      "title": "Store remain mem",
+      "tooltip": {
+        "shared": true,
+        "sort": 0,
+        "value_type": "individual"
+      },
+      "type": "graph",
+      "xaxis": {
+        "buckets": null,
+        "mode": "time",
+        "name": null,
+        "show": true,
+        "values": []
+      },
+      "yaxes": [
+        {
+          "format": "deckbytes",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        },
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        }
+      ],
+      "yaxis": {
+        "align": false,
+        "alignLevel": null
+      }
     }
   ],
   "refresh": false,
@@ -1230,9 +1305,8 @@
     "list": [
       {
         "current": {
-          "tags": [],
+          "text": "prometheus",
-          "text": "Prometheus",
+          "value": "prometheus"
-          "value": "Prometheus"
         },
         "hide": 0,
         "label": "datasource",
@@ -1245,10 +1319,7 @@
       },
       {
         "allValue": null,
-        "current": {
+        "current": {},
-          "text": "example",
-          "value": "example"
-        },
         "datasource": "$datasource",
         "hide": 0,
         "includeAll": false,
@@ -1269,7 +1340,7 @@
     ]
   },
   "time": {
-    "from": "now-1h",
+    "from": "now-6h",
     "to": "now"
   },
   "timepicker": {
@@ -1300,5 +1371,5 @@
   "timezone": "",
   "title": "Canal instances",
   "uid": "8vh8NGpiz",
-  "version": 1
+  "version": 103
 }

parse/src/main/java/com/alibaba/otter/canal/parse/inbound/mysql/AbstractMysqlEventParser.java

@@ -38,6 +38,8 @@ public abstract class AbstractMysqlEventParser extends AbstractEventParser {
     protected boolean              filterRows                = false;
     protected boolean              filterTableError          = false;
     protected boolean              useDruidDdlFilter         = true;
+    // instance received binlog bytes
+    protected final AtomicLong     receivedBinlogBytes       = new AtomicLong(0L);
     private final AtomicLong       eventsPublishBlockingTime = new AtomicLong(0L);
 
     protected BinlogParser buildParser() {
@@ -204,4 +206,8 @@ public abstract class AbstractMysqlEventParser extends AbstractEventParser {
         return this.eventsPublishBlockingTime;
     }
 
+    public AtomicLong getReceivedBinlogBytes() {
+        return this.receivedBinlogBytes;
+    }
+
 }

parse/src/main/java/com/alibaba/otter/canal/parse/inbound/mysql/MysqlEventParser.java

@@ -71,9 +71,6 @@ public class MysqlEventParser extends AbstractMysqlEventParser implements CanalE
     private int                  dumpErrorCount                    = 0;                 // binlogDump失败异常计数
     private int                  dumpErrorCountThreshold           = 2;                 // binlogDump失败异常计数阀值
 
-    // instance received binlog bytes
-    private final AtomicLong     receivedBinlogBytes               = new AtomicLong(0L);
-
     protected ErosaConnection buildErosaConnection() {
         return buildMysqlConnection(this.runningInfo);
     }
@@ -907,8 +904,4 @@ public class MysqlEventParser extends AbstractMysqlEventParser implements CanalE
         this.dumpErrorCountThreshold = dumpErrorCountThreshold;
     }
 
-    public AtomicLong getReceivedBinlogBytes() {
-        return this.receivedBinlogBytes;
-    }
-
 }

prometheus/src/main/java/com/alibaba/otter/canal/prometheus/impl/ParserCollector.java

@@ -1,14 +1,15 @@
 package com.alibaba.otter.canal.prometheus.impl;
 
 import static com.alibaba.otter.canal.prometheus.CanalInstanceExports.DEST;
-import static com.alibaba.otter.canal.prometheus.CanalInstanceExports.DEST_LABELS_LIST;
+
+import com.alibaba.otter.canal.parse.inbound.group.GroupEventParser;
+import com.alibaba.otter.canal.parse.inbound.mysql.AbstractMysqlEventParser;
 import io.prometheus.client.Collector;
 import io.prometheus.client.CounterMetricFamily;
 import io.prometheus.client.GaugeMetricFamily;
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
@@ -19,7 +20,6 @@ import org.slf4j.LoggerFactory;
 
 import com.alibaba.otter.canal.instance.core.CanalInstance;
 import com.alibaba.otter.canal.parse.CanalEventParser;
-import com.alibaba.otter.canal.parse.inbound.mysql.MysqlEventParser;
 import com.alibaba.otter.canal.prometheus.InstanceRegistry;
 import com.google.common.base.Preconditions;
 
@@ -34,11 +34,13 @@ public class ParserCollector extends Collector implements InstanceRegistry {
     private static final String                              RECEIVED_BINLOG       = "canal_instance_received_binlog_bytes";
     private static final String                              PARSER_MODE           = "canal_instance_parser_mode";
     private static final String                              MODE_LABEL            = "parallel";
+    private static final String                              PARSER_LABEL          = "parser";
     private static final String                              PUBLISH_BLOCKING_HELP = "Publish blocking time of dump thread in milliseconds";
     private static final String                              RECEIVED_BINLOG_HELP  = "Received binlog bytes";
     private static final String                              MODE_HELP             = "Parser mode(parallel/serial) of instance";
     private final List<String>                               modeLabels            = Arrays.asList(DEST, MODE_LABEL);
-    private final ConcurrentMap<String, ParserMetricsHolder> instances             = new ConcurrentHashMap<String, ParserMetricsHolder>();
+    private final List<String>                               parserLabels          = Arrays.asList(DEST, PARSER_LABEL);
+    private final ConcurrentMap<String, ParserMetricsHolder> instances             = new ConcurrentHashMap<>();
 
     private ParserCollector() {}
 
@@ -52,53 +54,87 @@ public class ParserCollector extends Collector implements InstanceRegistry {
 
     @Override
     public List<MetricFamilySamples> collect() {
-        List<MetricFamilySamples> mfs = new ArrayList<MetricFamilySamples>();
+        List<MetricFamilySamples> mfs = new ArrayList<>();
-        boolean hasParallel = false;
         CounterMetricFamily bytesCounter = new CounterMetricFamily(RECEIVED_BINLOG,
-                RECEIVED_BINLOG_HELP, DEST_LABELS_LIST);
+                RECEIVED_BINLOG_HELP, parserLabels);
         GaugeMetricFamily modeGauge = new GaugeMetricFamily(PARSER_MODE,
                 MODE_HELP, modeLabels);
         CounterMetricFamily blockingCounter = new CounterMetricFamily(PUBLISH_BLOCKING,
-                PUBLISH_BLOCKING_HELP, DEST_LABELS_LIST);
+                PUBLISH_BLOCKING_HELP, parserLabels);
         for (ParserMetricsHolder emh : instances.values()) {
-            if (emh.isParallel) {
+            if (emh instanceof GroupParserMetricsHolder) {
-                blockingCounter.addMetric(emh.destLabelValues, (emh.eventsPublishBlockingTime.doubleValue() / NANO_PER_MILLI));
+                GroupParserMetricsHolder group = (GroupParserMetricsHolder) emh;
-                hasParallel = true;
+                for (ParserMetricsHolder semh :  group.holders) {
+                    singleCollect(bytesCounter, blockingCounter, modeGauge, semh);
+                }
+            }
+            else {
+                singleCollect(bytesCounter, blockingCounter, modeGauge, emh);
             }
-            modeGauge.addMetric(emh.modeLabelValues, 1);
-            bytesCounter.addMetric(emh.destLabelValues, emh.receivedBinlogBytes.doubleValue());
-
         }
         mfs.add(bytesCounter);
         mfs.add(modeGauge);
-        if (hasParallel) {
+        if (!blockingCounter.samples.isEmpty()) {
             mfs.add(blockingCounter);
         }
         return mfs;
     }
 
+    private void singleCollect(CounterMetricFamily bytesCounter, CounterMetricFamily blockingCounter, GaugeMetricFamily modeGauge, ParserMetricsHolder holder) {
+        if (holder.isParallel) {
+            blockingCounter.addMetric(holder.parserLabelValues, (holder.eventsPublishBlockingTime.doubleValue() / NANO_PER_MILLI));
+        }
+        modeGauge.addMetric(holder.modeLabelValues, 1);
+        bytesCounter.addMetric(holder.parserLabelValues, holder.receivedBinlogBytes.doubleValue());
+    }
+
     @Override
     public void register(CanalInstance instance) {
         final String destination = instance.getDestination();
-        ParserMetricsHolder holder = new ParserMetricsHolder();
+        ParserMetricsHolder holder;
         CanalEventParser parser = instance.getEventParser();
-        if (!(parser instanceof MysqlEventParser)) {
+        if (parser instanceof AbstractMysqlEventParser) {
-            throw new IllegalArgumentException("CanalEventParser must be MysqlEventParser");
+            holder = singleHolder(destination, (AbstractMysqlEventParser)parser, "0");
+        } else if (parser instanceof GroupEventParser) {
+            holder = groupHolder(destination, (GroupEventParser)parser);
+        } else {
+            throw new IllegalArgumentException("CanalEventParser must be either AbstractMysqlEventParser or GroupEventParser.");
         }
-        MysqlEventParser mysqlParser = (MysqlEventParser) parser;
+        Preconditions.checkNotNull(holder);
-        holder.destLabelValues = Collections.singletonList(destination);
-        holder.modeLabelValues = Arrays.asList(destination, Boolean.toString(mysqlParser.isParallel()));
-        holder.eventsPublishBlockingTime = mysqlParser.getEventsPublishBlockingTime();
-        holder.receivedBinlogBytes = mysqlParser.getReceivedBinlogBytes();
-        holder.isParallel = mysqlParser.isParallel();
-        Preconditions.checkNotNull(holder.eventsPublishBlockingTime);
-        Preconditions.checkNotNull(holder.receivedBinlogBytes);
         ParserMetricsHolder old = instances.put(destination, holder);
         if (old != null) {
             logger.warn("Remove stale ParserCollector for instance {}.", destination);
         }
     }
 
+    private ParserMetricsHolder singleHolder(String destination, AbstractMysqlEventParser parser, String id) {
+        ParserMetricsHolder holder = new ParserMetricsHolder();
+        holder.parserLabelValues = Arrays.asList(destination, id);
+        holder.modeLabelValues = Arrays.asList(destination, Boolean.toString(parser.isParallel()));
+        holder.eventsPublishBlockingTime = parser.getEventsPublishBlockingTime();
+        holder.receivedBinlogBytes = parser.getReceivedBinlogBytes();
+        holder.isParallel = parser.isParallel();
+        Preconditions.checkNotNull(holder.eventsPublishBlockingTime);
+        Preconditions.checkNotNull(holder.receivedBinlogBytes);
+        return holder;
+    }
+
+    private GroupParserMetricsHolder groupHolder(String destination, GroupEventParser group) {
+        List<CanalEventParser> parsers = group.getEventParsers();
+        GroupParserMetricsHolder groupHolder = new GroupParserMetricsHolder();
+        int num = parsers.size();
+        for (int i = 0; i < num; i ++) {
+            CanalEventParser parser = parsers.get(i);
+            if (parser instanceof AbstractMysqlEventParser) {
+                ParserMetricsHolder single = singleHolder(destination, (AbstractMysqlEventParser)parser, Integer.toString(i + 1));
+                groupHolder.holders.add(single);
+            } else {
+                logger.warn("Null or non AbstractMysqlEventParser, ignore.");
+            }
+        }
+        return groupHolder;
+    }
+
     @Override
     public void unregister(CanalInstance instance) {
         final String destination = instance.getDestination();
@@ -106,11 +142,17 @@ public class ParserCollector extends Collector implements InstanceRegistry {
     }
 
     private class ParserMetricsHolder {
-        private List<String> destLabelValues;
+        private List<String> parserLabelValues;
         private List<String> modeLabelValues;
+        // metrics for single parser
         private AtomicLong   receivedBinlogBytes;
         private AtomicLong   eventsPublishBlockingTime;
+        // parser mode
         private boolean      isParallel;
     }
 
+    private class GroupParserMetricsHolder extends ParserMetricsHolder {
+        private final List<ParserMetricsHolder> holders = new ArrayList<>();
+    }
+
 }