From 339668ac935f781c06225d2d685642e27348772b Mon Sep 17 00:00:00 2001
From: Dan Engelbrecht <dan.engelbrecht@epicgames.com>
Date: Wed, 10 Sep 2025 16:38:33 +0200
Subject: add EMode to WorkerTheadPool to avoid thread starvation (#492)

- Improvement: Add a new mode to worker thread pools to avoid starvation of workers which could cause long stalls due to other work begin queued up. UE-305498
---
 src/zencore/filesystem.cpp | 42 ++++++++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

(limited to 'src/zencore/filesystem.cpp')

diff --git a/src/zencore/filesystem.cpp b/src/zencore/filesystem.cpp
index 8327838c9..5125beeca 100644
--- a/src/zencore/filesystem.cpp
+++ b/src/zencore/filesystem.cpp
@@ -2439,26 +2439,28 @@ GetDirectoryContent(const std::filesystem::path& RootDir,
 				PendingWorkCount.AddCount(1);
 				try
 				{
-					WorkerPool.ScheduleWork([WorkerPool		  = &WorkerPool,
-											 PendingWorkCount = &PendingWorkCount,
-											 Visitor		  = Visitor,
-											 Flags			  = Flags,
-											 Path			  = std::move(Path),
-											 RelativeRoot	  = RelativeRoot / DirectoryName]() {
-						ZEN_ASSERT(Visitor);
-						auto _ = MakeGuard([&]() { PendingWorkCount->CountDown(); });
-						try
-						{
-							MultithreadedVisitor SubVisitor(*WorkerPool, *PendingWorkCount, RelativeRoot, Flags, Visitor);
-							FileSystemTraversal	 Traversal;
-							Traversal.TraverseFileSystem(Path, SubVisitor);
-							Visitor->AsyncVisitDirectory(SubVisitor.RelativeRoot, std::move(SubVisitor.Content));
-						}
-						catch (const std::exception& Ex)
-						{
-							ZEN_ERROR("Failed scheduling work to scan subfolder '{}'. Reason: '{}'", Path / RelativeRoot, Ex.what());
-						}
-					});
+					WorkerPool.ScheduleWork(
+						[WorkerPool		  = &WorkerPool,
+						 PendingWorkCount = &PendingWorkCount,
+						 Visitor		  = Visitor,
+						 Flags			  = Flags,
+						 Path			  = std::move(Path),
+						 RelativeRoot	  = RelativeRoot / DirectoryName]() {
+							ZEN_ASSERT(Visitor);
+							auto _ = MakeGuard([&]() { PendingWorkCount->CountDown(); });
+							try
+							{
+								MultithreadedVisitor SubVisitor(*WorkerPool, *PendingWorkCount, RelativeRoot, Flags, Visitor);
+								FileSystemTraversal	 Traversal;
+								Traversal.TraverseFileSystem(Path, SubVisitor);
+								Visitor->AsyncVisitDirectory(SubVisitor.RelativeRoot, std::move(SubVisitor.Content));
+							}
+							catch (const std::exception& Ex)
+							{
+								ZEN_ERROR("Failed scheduling work to scan subfolder '{}'. Reason: '{}'", Path / RelativeRoot, Ex.what());
+							}
+						},
+						WorkerThreadPool::EMode::DisableBacklog);
 				}
 				catch (const std::exception Ex)
 				{
-- 
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