Merge pull request #20818 from vespa-engine/geirst/subtract-transient…

…-resource-usage-before-reporting-to-cc

Subtract transient resource usage from the absolute usage before repo…

searchcore/src/tests/proton/persistenceengine/resource_usage_tracker/resource_usage_tracker_test.cpp

@@ -57,9 +57,10 @@ class ResourceUsageTrackerTest : public ::testing::Test
 
     ~ResourceUsageTrackerTest();
 
-    void notify(double disk_usage, double memory_usage)
+    void notify(double disk_usage, double memory_usage, double transient_disk_usage = 0.0, double transient_memory_usage = 0.0)
     {
-        _notifier.notify(DiskMemUsageState({ 0.8, disk_usage }, { 0.8, memory_usage }));
+        _notifier.notify(DiskMemUsageState({ 0.8, disk_usage }, { 0.8, memory_usage },
+                                           transient_disk_usage, transient_memory_usage));
     }
 
     ResourceUsage get_usage() { return _listener->get_usage(); }
@@ -77,6 +78,15 @@ TEST_F(ResourceUsageTrackerTest, resource_usage_is_forwarded_to_listener)
     EXPECT_EQ(ResourceUsage(0.75, 0.25), get_usage());
 }
 
+TEST_F(ResourceUsageTrackerTest, transient_resource_usage_is_subtracted_from_absolute_usage)
+{
+    auto register_guard = _tracker->set_listener(*_listener);
+    notify(0.8, 0.5, 0.4, 0.2);
+    EXPECT_EQ(ResourceUsage(0.4, 0.3), get_usage());
+    notify(0.8, 0.5, 0.9, 0.6);
+    EXPECT_EQ(ResourceUsage(0.0, 0.0), get_usage());
+}
+
 TEST_F(ResourceUsageTrackerTest, forwarding_depends_on_register_guard)
 {
     auto register_guard = _tracker->set_listener(*_listener);

searchcore/src/vespa/searchcore/proton/persistenceengine/resource_usage_tracker.cpp

@@ -94,8 +94,13 @@ void
 ResourceUsageTracker::notifyDiskMemUsage(DiskMemUsageState state)
 {
     std::lock_guard guard(_lock);
-    // TODO: Subtract transient resource (memory and disk) usage from the absolute numbers.
-    _resource_usage = ResourceUsage(state.diskState().usage(), state.memoryState().usage(), _resource_usage.get_attribute_address_space_usage());
+    // The transient resource usage is subtracted from the absolute resource usage
+    // before it eventually is reported to the cluster controller (to decide whether to block client feed).
+    // This ensures that the transient resource usage is covered by the resource headroom on the content node,
+    // instead of leading to feed blocked due to natural fluctuations.
+    double adj_disk_usage = std::max(0.0, state.diskState().usage() - state.transient_disk_usage());
+    double adj_memory_usage = std::max(0.0, state.memoryState().usage() - state.transient_memory_usage());
+    _resource_usage = ResourceUsage(adj_disk_usage, adj_memory_usage, _resource_usage.get_attribute_address_space_usage());
     if (_listener != nullptr) {
         _listener->update_resource_usage(_resource_usage);
     }