core: outlier detection max ejection logic update (#9492) (#9552)

Stop further ejection if the ejection percentage is lesser than or equal to the maximum ejection percentage. Previously this was only done when the current ejection percentage was lesser than the maximum.
grpc · Sep 15, 2022 · 8b9acff · 8b9acff
1 parent 0707aac
commit 8b9acff
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Showing 2 changed files with 11 additions and 9 deletions.
diff --git a/core/src/main/java/io/grpc/util/OutlierDetectionLoadBalancer.java b/core/src/main/java/io/grpc/util/OutlierDetectionLoadBalancer.java
@@ -733,10 +733,11 @@ public void ejectOutliers(AddressTrackerMap trackerMap, long ejectionTimeNanos)
           mean - stdev * (config.successRateEjection.stdevFactor / 1000f);
 
       for (AddressTracker tracker : trackersWithVolume) {
-        // If we are above the max ejection percentage, don't eject any more. This will allow the
-        // total ejections to go one above the max, but at the same time it assures at least one
-        // ejection, which the spec calls for. This behavior matches what Envoy proxy does.
-        if (trackerMap.ejectionPercentage() > config.maxEjectionPercent) {
+        // If we are above or equal to the max ejection percentage, don't eject any more. This will
+        // allow the total ejections to go one above the max, but at the same time it assures at
+        // least one ejection, which the spec calls for. This behavior matches what Envoy proxy
+        // does.
+        if (trackerMap.ejectionPercentage() >= config.maxEjectionPercent) {
           return;
         }
 
@@ -797,10 +798,11 @@ public void ejectOutliers(AddressTrackerMap trackerMap, long ejectionTimeNanos)
 
       // If this address does not have enough volume to be considered, skip to the next one.
       for (AddressTracker tracker : trackersWithVolume) {
-        // If we are above the max ejection percentage, don't eject any more. This will allow the
-        // total ejections to go one above the max, but at the same time it assures at least one
-        // ejection, which the spec calls for. This behavior matches what Envoy proxy does.
-        if (trackerMap.ejectionPercentage() > config.maxEjectionPercent) {
+        // If we are above or equal to the max ejection percentage, don't eject any more. This will
+        // allow the total ejections to go one above the max, but at the same time it assures at
+        // least one ejection, which the spec calls for. This behavior matches what Envoy proxy
+        // does.
+        if (trackerMap.ejectionPercentage() >= config.maxEjectionPercent) {
           return;
         }
 

diff --git a/core/src/test/java/io/grpc/util/OutlierDetectionLoadBalancerTest.java b/core/src/test/java/io/grpc/util/OutlierDetectionLoadBalancerTest.java
@@ -585,7 +585,7 @@ public void successRateTwoOutliers() {
   @Test
   public void successRateThreeOutliers_maxEjectionPercentage() {
     OutlierDetectionLoadBalancerConfig config = new OutlierDetectionLoadBalancerConfig.Builder()
-        .setMaxEjectionPercent(20)
+        .setMaxEjectionPercent(30)
         .setSuccessRateEjection(
             new SuccessRateEjection.Builder()
                 .setMinimumHosts(3)