[JENKINS-75152] Update hudson.model.Queue for long buildableItem queue cycle acceleration (#10234)

Author: krisstern

core/src/main/java/hudson/model/Queue.java

@@ -1615,6 +1615,9 @@ public void maintain() {
             // Ensure that identification of blocked tasks is using the live state: JENKINS-27708 & JENKINS-27871
             updateSnapshot();
 
+            // JENKINS-75152. Save the label and blockage reasons of items that have no candidates into this map.
+            // It is used to speed up the judgement of other buildable items with the same label.
+            Map<Label, List<CauseOfBlockage>> noCandidateLabelsMap = new HashMap<>();
             // allocate buildable jobs to executors
             for (BuildableItem p : new ArrayList<>(
                     buildables)) { // copy as we'll mutate the list in the loop
@@ -1641,6 +1644,13 @@ public void maintain() {
                         updateSnapshot();
                     }
                 } else {
+                    // JENKINS-75152. Skip the remaining steps if the label of this item has been determined
+                    // to have no candidate executors in the previous allocation process.
+                    Label itemLabel = p.getAssignedLabel();
+                    if (noCandidateLabelsMap.containsKey(itemLabel)) {
+                        p.transientCausesOfBlockage = noCandidateLabelsMap.get(itemLabel);
+                        continue;
+                    }
 
                     List<JobOffer> candidates = new ArrayList<>(parked.size());
                     Map<Node, CauseOfBlockage> reasonMap = new HashMap<>();
@@ -1673,6 +1683,11 @@ public void maintain() {
                                 new Object[]{p, candidates, parked.values()});
                         List<CauseOfBlockage> reasons = reasonMap.values().stream().filter(Objects::nonNull).collect(Collectors.toList());
                         p.transientCausesOfBlockage = reasons.isEmpty() ? null : reasons;
+                        // If no candidates, save the label and blockage reasons.
+                        if (candidates.isEmpty()) {
+                            noCandidateLabelsMap.put(itemLabel, p.transientCausesOfBlockage);
+                            LOGGER.log(Level.FINEST, "{0} changes to the state of no candidate executor", itemLabel);
+                        }
                         continue;
                     }