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

1 files changed, 15 insertions, 13 deletions

diff --git a/src/zenutil/buildstoragecache.cpp b/src/zenutil/buildstoragecache.cpp
index 2171f4d62..e5e8db8d2 100644
--- a/src/zenutil/buildstoragecache.cpp
+++ b/src/zenutil/buildstoragecache.cpp
@@ -65,21 +65,23 @@ public:
 		m_PendingBackgroundWorkCount.AddCount(1);
 		try
 		{
-			m_BackgroundWorkPool.ScheduleWork([this, Work = std::move(Work)]() {
-				ZEN_TRACE_CPU("ZenBuildStorageCache::BackgroundWork");
-				auto _ = MakeGuard([this]() { m_PendingBackgroundWorkCount.CountDown(); });
-				if (!m_CancelBackgroundWork)
-				{
-					try
-					{
-						Work();
-					}
-					catch (const std::exception& Ex)
+			m_BackgroundWorkPool.ScheduleWork(
+				[this, Work = std::move(Work)]() {
+					ZEN_TRACE_CPU("ZenBuildStorageCache::BackgroundWork");
+					auto _ = MakeGuard([this]() { m_PendingBackgroundWorkCount.CountDown(); });
+					if (!m_CancelBackgroundWork)
 					{
-						ZEN_ERROR("Failed executing background upload to build cache. Reason: {}", Ex.what());
+						try
+						{
+							Work();
+						}
+						catch (const std::exception& Ex)
+						{
+							ZEN_ERROR("Failed executing background upload to build cache. Reason: {}", Ex.what());
+						}
 					}
-				}
-			});
+				},
+				WorkerThreadPool::EMode::EnableBacklog);
 		}
 		catch (const std::exception& Ex)
 		{