[GitHub] [skywalking] muse-dev[bot] commented on a change in pull request #6602: Enhance the export service.

[GitBox <gi...@apache.org>]

muse-dev[bot] commented on a change in pull request #6602:
URL: https://github.com/apache/skywalking/pull/6602#discussion_r599452462



##########
File path: oap-server/exporter/src/main/java/org/apache/skywalking/oap/server/exporter/provider/grpc/GRPCExporter.java
##########
@@ -67,27 +73,52 @@ public GRPCExporter(GRPCExporterSetting setting) {
         blockingStub = MetricExportServiceGrpc.newBlockingStub(channel);
         exportBuffer = new DataCarrier<ExportData>(setting.getBufferChannelNum(), setting.getBufferChannelSize());
         exportBuffer.consume(this, 1, 200);
-        subscriptionSet = new HashSet<>();
+        subscriptionList = new ArrayList<>();
+        fetchListLock = new ReentrantLock();
     }
 
     @Override
     public void export(ExportEvent event) {
-        if (ExportEvent.EventType.TOTAL == event.getType()) {
-            Metrics metrics = event.getMetrics();
-            if (metrics instanceof WithMetadata) {
-                MetricsMetaInfo meta = ((WithMetadata) metrics).getMeta();
-                if (subscriptionSet.size() == 0 || subscriptionSet.contains(meta.getMetricsName())) {
-                    exportBuffer.produce(new ExportData(meta, metrics));
-                }
+        Metrics metrics = event.getMetrics();
+        if (metrics instanceof WithMetadata) {
+            MetricsMetaInfo meta = ((WithMetadata) metrics).getMeta();
+            if (subscriptionList.size() == 0 && ExportEvent.EventType.INCREMENT.equals(event.getType())) {

Review comment:
       *THREAD_SAFETY_VIOLATION:*  Read/Write race. Non-private method `GRPCExporter.export(...)` reads without synchronization from container `this.subscriptionList` via call to `List.size()`. Potentially races with write in method `GRPCExporter.fetchSubscriptionList()`.
    Reporting because another access to the same memory occurs on a background thread, although this access may not.
   (at-me [in a reply](https://docs.muse.dev/docs/talk-to-muse/) with `help` or `ignore`)




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