Export estimated merge memory usage metric

Having visibility of this number will make it easier to choose
sensible defaults based on observations of existing systems.

3 files changed, 3 insertions, 0 deletions

diff --git a/metrics/src/main/java/ai/vespa/metrics/StorageMetrics.java b/metrics/src/main/java/ai/vespa/metrics/StorageMetrics.java
index db7b7fec494..f52147c1e17 100644
--- a/metrics/src/main/java/ai/vespa/metrics/StorageMetrics.java
+++ b/metrics/src/main/java/ai/vespa/metrics/StorageMetrics.java
@@ -96,6 +96,7 @@ public enum StorageMetrics implements VespaMetrics {
     VDS_MERGETHROTTLER_AVERAGEQUEUEWAITINGTIME("vds.mergethrottler.averagequeuewaitingtime", Unit.MILLISECOND, "Time merges spent in the throttler queue"),
     VDS_MERGETHROTTLER_QUEUESIZE("vds.mergethrottler.queuesize", Unit.INSTANCE, "Length of merge queue"),
     VDS_MERGETHROTTLER_ACTIVE_WINDOW_SIZE("vds.mergethrottler.active_window_size", Unit.INSTANCE, "Number of merges active within the pending window size"),
+    VDS_MERGETHROTTLER_ESTIMATED_MERGE_MEMORY_USAGE("vds.mergethrottler.estimated_merge_memory_usage", Unit.BYTE, "An estimated upper bound of the  memory usage (in bytes) of the merges currently in the active window"),
     VDS_MERGETHROTTLER_BOUNCED_DUE_TO_BACK_PRESSURE("vds.mergethrottler.bounced_due_to_back_pressure", Unit.INSTANCE, "Number of merges bounced due to resource exhaustion back-pressure"),
     VDS_MERGETHROTTLER_LOCALLYEXECUTEDMERGES_OK("vds.mergethrottler.locallyexecutedmerges.ok", Unit.INSTANCE, "The number of successful merges for 'locallyexecutedmerges'"),
     VDS_MERGETHROTTLER_LOCALLYEXECUTEDMERGES_FAILURES_ABORTED("vds.mergethrottler.locallyexecutedmerges.failures.aborted", Unit.OPERATION, "The number of merges that failed because the storage node was (most likely) shutting down"),
diff --git a/metrics/src/main/java/ai/vespa/metrics/set/Vespa9VespaMetricSet.java b/metrics/src/main/java/ai/vespa/metrics/set/Vespa9VespaMetricSet.java
index 4174aa6cb53..b0286fd6e0f 100644
--- a/metrics/src/main/java/ai/vespa/metrics/set/Vespa9VespaMetricSet.java
+++ b/metrics/src/main/java/ai/vespa/metrics/set/Vespa9VespaMetricSet.java
@@ -530,6 +530,7 @@ public class Vespa9VespaMetricSet {
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_AVERAGEQUEUEWAITINGTIME, EnumSet.of(max, sum, count));
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_QUEUESIZE, EnumSet.of(max, sum, count));
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_ACTIVE_WINDOW_SIZE, EnumSet.of(max, sum, count));
+        addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_ESTIMATED_MERGE_MEMORY_USAGE, EnumSet.of(max, sum, count));
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_BOUNCED_DUE_TO_BACK_PRESSURE.rate());
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_LOCALLYEXECUTEDMERGES_OK.rate());
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_MERGECHAINS_OK.rate());
diff --git a/metrics/src/main/java/ai/vespa/metrics/set/VespaMetricSet.java b/metrics/src/main/java/ai/vespa/metrics/set/VespaMetricSet.java
index a6ac18cf011..33f137c2b98 100644
--- a/metrics/src/main/java/ai/vespa/metrics/set/VespaMetricSet.java
+++ b/metrics/src/main/java/ai/vespa/metrics/set/VespaMetricSet.java
@@ -604,6 +604,7 @@ public class VespaMetricSet {
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_AVERAGEQUEUEWAITINGTIME, EnumSet.of(max, sum, count));
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_QUEUESIZE, EnumSet.of(max, sum, count));
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_ACTIVE_WINDOW_SIZE, EnumSet.of(max, sum, count));
+        addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_ESTIMATED_MERGE_MEMORY_USAGE, EnumSet.of(max, sum, count));
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_BOUNCED_DUE_TO_BACK_PRESSURE.rate());
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_LOCALLYEXECUTEDMERGES_OK.rate());
         addMetric(metrics, StorageMetrics.VDS_MERGETHROTTLER_MERGECHAINS_OK.rate());