Only keep the most recent 50 failure events

SingularityBase/src/main/java/com/hubspot/singularity/SingularityDeployStatisticsBuilder.java

@@ -2,8 +2,10 @@
 
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ListMultimap;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 public class SingularityDeployStatisticsBuilder {
   private final String requestId;
@@ -173,6 +175,16 @@ public SingularityDeployStatisticsBuilder addTaskFailureEvent(
     return this;
   }
 
+  public SingularityDeployStatisticsBuilder trimTaskFailureEvents(int countToKeep) {
+    this.taskFailureEvents =
+      taskFailureEvents
+        .stream()
+        .sorted(Comparator.comparingLong(TaskFailureEvent::getTimestamp).reversed())
+        .limit(countToKeep)
+        .collect(Collectors.toList());
+    return this;
+  }
+
   @Override
   public String toString() {
     return (

SingularityService/src/main/java/com/hubspot/singularity/scheduler/SingularityScheduler.java

@@ -1372,6 +1372,7 @@ private void updateDeployStatistics(
       bldr.setNumSequentialRetries(0);
     }
 
+    bldr.trimTaskFailureEvents(50);
     final SingularityDeployStatistics newStatistics = bldr.build();
 
     LOG.trace("Saving new deploy statistics {}", newStatistics);