Add flag to control number of processors a non-application jvm gets to use.

Intention is to lower this number from 2 to 1 in order to reduce memory footprint
for small containers.

4 files changed, 15 insertions, 2 deletions

diff --git a/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java b/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
index f4cffd5a724..d509fa5dd6a 100644
--- a/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
+++ b/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
@@ -84,6 +84,7 @@ public interface ModelContext {
         @ModelFeatureFlag(owners = {"baldersheim"}) default double feedConcurrency() { throw new UnsupportedOperationException("TODO specify default value"); }
         @ModelFeatureFlag(owners = {"baldersheim"}, removeAfter = "7.527") default int metricsproxyNumThreads() { return defaultPoolNumThreads(); }
         @ModelFeatureFlag(owners = {"baldersheim"}) default int defaultPoolNumThreads() { return 2; }
+        @ModelFeatureFlag(owners = {"baldersheim"}) default int availableProcessors() { return 2; }
         @ModelFeatureFlag(owners = {"baldersheim"}, removeAfter = "7.527") default int largeRankExpressionLimit() { return 8192; }
         @ModelFeatureFlag(owners = {"baldersheim"}) default int maxUnCommittedMemory() { return 130000; }
         @ModelFeatureFlag(owners = {"baldersheim"}) default int maxConcurrentMergesPerNode() { return 16; }
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/container/ContainerCluster.java b/config-model/src/main/java/com/yahoo/vespa/model/container/ContainerCluster.java
index 7010d7b3d4e..982d886cbea 100755
--- a/config-model/src/main/java/com/yahoo/vespa/model/container/ContainerCluster.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/container/ContainerCluster.java
@@ -146,6 +146,7 @@ public abstract class ContainerCluster<CONTAINER extends Container>
     private final ComponentGroup<Component<?, ?>> componentGroup;
     private final boolean isHostedVespa;
     private final boolean zooKeeperLocalhostAffinity;
+    private final int numAvailableProcessors;
 
     private final Map<String, String> concreteDocumentTypes = new LinkedHashMap<>();
 
@@ -166,6 +167,7 @@ public abstract class ContainerCluster<CONTAINER extends Container>
         this.isHostedVespa = stateIsHosted(deployState);
         this.zone = (deployState != null) ? deployState.zone() : Zone.defaultZone();
         this.zooKeeperLocalhostAffinity = zooKeeperLocalhostAffinity;
+        numAvailableProcessors = deployState.featureFlags().availableProcessors();
 
         componentGroup = new ComponentGroup<>(this, "component");
 
@@ -493,7 +495,7 @@ public abstract class ContainerCluster<CONTAINER extends Container>
     public void getConfig(QrStartConfig.Builder builder) {
         builder.jvm
                 .verbosegc(false)
-                .availableProcessors(2)
+                .availableProcessors(numAvailableProcessors)
                 .compressedClassSpaceSize(32)
                 .minHeapsize(32)
                 .heapsize(256)
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java
index 03ba8fd5efd..b8f79682a03 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java
@@ -187,6 +187,7 @@ public class ModelContextImpl implements ModelContext {
         private final double resourceLimitMemory;
         private final double minNodeRatioPerGroup;
         private final int metricsproxyNumThreads;
+        private final int availableProcessors;
         private final boolean containerDumpHeapOnShutdownTimeout;
         private final double containerShutdownTimeout;
         private final int maxUnCommittedMemory;
@@ -225,9 +226,10 @@ public class ModelContextImpl implements ModelContext {
             this.resourceLimitMemory = flagValue(source, appId, PermanentFlags.RESOURCE_LIMIT_MEMORY);
             this.minNodeRatioPerGroup = flagValue(source, appId, Flags.MIN_NODE_RATIO_PER_GROUP);
             this.metricsproxyNumThreads = flagValue(source, appId, Flags.METRICSPROXY_NUM_THREADS);
+            this.availableProcessors = flagValue(source, appId, Flags.AVAILABLE_PROCESSORS);
             this.containerDumpHeapOnShutdownTimeout = flagValue(source, appId, Flags.CONTAINER_DUMP_HEAP_ON_SHUTDOWN_TIMEOUT);
             this.containerShutdownTimeout = flagValue(source, appId,Flags.CONTAINER_SHUTDOWN_TIMEOUT);
-            this.maxUnCommittedMemory = flagValue(source, appId, Flags.MAX_UNCOMMITTED_MEMORY);;
+            this.maxUnCommittedMemory = flagValue(source, appId, Flags.MAX_UNCOMMITTED_MEMORY);
             this.forwardIssuesAsErrors = flagValue(source, appId, PermanentFlags.FORWARD_ISSUES_AS_ERRORS);
             this.ignoreThreadStackSizes = flagValue(source, appId, Flags.IGNORE_THREAD_STACK_SIZES);
             this.unorderedMergeChaining = flagValue(source, appId, Flags.UNORDERED_MERGE_CHAINING);
@@ -265,6 +267,7 @@ public class ModelContextImpl implements ModelContext {
         @Override public double resourceLimitMemory() { return resourceLimitMemory; }
         @Override public double minNodeRatioPerGroup() { return minNodeRatioPerGroup; }
         @Override public int defaultPoolNumThreads() { return metricsproxyNumThreads; }
+        @Override public int availableProcessors() { return availableProcessors; }
         @Override public double containerShutdownTimeout() { return containerShutdownTimeout; }
         @Override public boolean containerDumpHeapOnShutdownTimeout() { return containerDumpHeapOnShutdownTimeout; }
         @Override public int maxUnCommittedMemory() { return maxUnCommittedMemory; }
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/Flags.java b/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
index 1013cd229b0..ce9f1c80a1e 100644
--- a/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
+++ b/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
@@ -222,6 +222,13 @@ public class Flags {
             "Takes effect at redeployment",
             ZONE_ID, APPLICATION_ID);
 
+    public static final UnboundIntFlag AVAILABLE_PROCESSORS = defineIntFlag(
+            "available-processors", 2,
+            List.of("balder"), "2022-18-01", "2022-04-01",
+            "Number of processors the jvm sees in non-application clusters",
+            "Takes effect at redeployment",
+            ZONE_ID, APPLICATION_ID);
+
     public static final UnboundBooleanFlag ENABLED_HORIZON_DASHBOARD = defineFeatureFlag(
             "enabled-horizon-dashboard", false,
             List.of("olaa"), "2021-09-13", "2022-02-01",