core: Eliminate NPE seen in PickFirstLeafLoadBalancer (#11013)

ref b/329420531

1 files changed, 7 insertions, 3 deletions

diff --git a/core/src/main/java/io/grpc/internal/PickFirstLeafLoadBalancer.java b/core/src/main/java/io/grpc/internal/PickFirstLeafLoadBalancer.java
index 3b222eaa1..108950c16 100644
--- a/core/src/main/java/io/grpc/internal/PickFirstLeafLoadBalancer.java
+++ b/core/src/main/java/io/grpc/internal/PickFirstLeafLoadBalancer.java
@@ -465,9 +465,13 @@ final class PickFirstLeafLoadBalancer extends LoadBalancer {
       log.log(Level.FINE, "Received health status {0} for subchannel {1}",
           new Object[]{newState, subchannelData.subchannel});
       healthStateInfo = newState;
-      if (addressIndex.isValid()
-          && subchannels.get(addressIndex.getCurrentAddress()).healthListener == this) {
-        updateHealthCheckedState(subchannelData);
+      try {
+        SubchannelData curSubChanData = subchannels.get(addressIndex.getCurrentAddress());
+        if (curSubChanData != null && curSubChanData.healthListener == this) {
+          updateHealthCheckedState(subchannelData);
+        }
+      } catch (IllegalStateException e) {
+        log.fine("Health listener received state change after subchannel was removed");
       }
     }
   }