core: fix drainPendingCalls might be called twice

Fixing the bug: if two consecutive name resolution updates are queued together in SynchronizationContext, drainPendingCalls() might be called twice and be broken.
dfawley · Jan 15, 2021 · 87d0ff6 · 87d0ff6
1 parent 689535b
commit 87d0ff6
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/core/src/main/java/io/grpc/internal/ManagedChannelImpl.java b/core/src/main/java/io/grpc/internal/ManagedChannelImpl.java
@@ -1568,6 +1568,7 @@ public void run() {
           Status serviceConfigError = configOrError != null ? configOrError.getError() : null;
 
           ManagedChannelServiceConfig effectiveServiceConfig;
+          InternalConfigSelector prevConfigSelector = configSelector.get();
           if (!lookUpServiceConfig) {
             if (validServiceConfig != null) {
               channelLogger.log(
@@ -1639,7 +1640,9 @@ public void run() {
                   re);
             }
           }
-          realChannel.drainPendingCalls();
+          if (prevConfigSelector == INITIAL_PENDING_SELECTOR) {
+            realChannel.drainPendingCalls();
+          }
 
           Attributes effectiveAttrs = resolutionResult.getAttributes();
           // Call LB only if it's not shutdown.  If LB is shutdown, lbHelper won't match.