Order Skyframe evaluations in a priority queue, with all children of a given node having the same priority, later enqueueings having higher priority, re-enqueued nodes having highest priority, and new root nodes having lowest priority. Experimentally, this can save significant RAM (1.4G in some builds!) while not affecting speed.

Also do a semi-drive-by deleting ExecutorFactory parameter to AbstractQueueVisitor, since it was always AbstractQueueVisitor.EXECUTOR_FACTORY.

PiperOrigin-RevId: 208560889

1 files changed, 3 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/skyframe/AbstractExceptionalParallelEvaluator.java b/src/main/java/com/google/devtools/build/skyframe/AbstractExceptionalParallelEvaluator.java
index f8f21f254e..268db07014 100644
--- a/src/main/java/com/google/devtools/build/skyframe/AbstractExceptionalParallelEvaluator.java
+++ b/src/main/java/com/google/devtools/build/skyframe/AbstractExceptionalParallelEvaluator.java
@@ -249,7 +249,9 @@ public abstract class AbstractExceptionalParallelEvaluator<E extends Exception>
         // This must be equivalent to the code in enqueueChild above, in order to be thread-safe.
         switch (entry.addReverseDepAndCheckIfDone(null)) {
           case NEEDS_SCHEDULING:
-            evaluatorContext.getVisitor().enqueueEvaluation(skyKey);
+            // Low priority because this node is not needed by any other currently evaluating node.
+            // So keep it at the back of the queue as long as there's other useful work to be done.
+            evaluatorContext.getVisitor().enqueueEvaluation(skyKey, Integer.MIN_VALUE);
             break;
           case DONE:
             informProgressReceiverThatValueIsDone(skyKey, entry);