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, 12 insertions, 7 deletions

diff --git a/src/zenstore/cas.cpp b/src/zenstore/cas.cpp
index 6b89beb3d..49d24c21e 100644
--- a/src/zenstore/cas.cpp
+++ b/src/zenstore/cas.cpp
@@ -132,13 +132,18 @@ CasImpl::Initialize(const CidStoreConfiguration& InConfig)
 		WorkerThreadPool&			   WorkerPool = GetMediumWorkerPool(EWorkloadType::Burst);
 		std::vector<std::future<void>> Work;
 		Work.emplace_back(
-			WorkerPool.EnqueueTask(std::packaged_task<void()>{[&]() { m_LargeStrategy.Initialize(m_Config.RootDirectory, IsNewStore); }}));
-		Work.emplace_back(WorkerPool.EnqueueTask(std::packaged_task<void()>{[&]() {
-			m_TinyStrategy.Initialize(m_Config.RootDirectory, "tobs", 1u << 28, 16, IsNewStore);  // 256 Mb per block
-		}}));
-		Work.emplace_back(WorkerPool.EnqueueTask(std::packaged_task<void()>{[&]() {
-			m_SmallStrategy.Initialize(m_Config.RootDirectory, "sobs", 1u << 30, 4096, IsNewStore);	 // 1 Gb per block
-		}}));
+			WorkerPool.EnqueueTask(std::packaged_task<void()>{[&]() { m_LargeStrategy.Initialize(m_Config.RootDirectory, IsNewStore); }},
+								   WorkerThreadPool::EMode::DisableBacklog));
+		Work.emplace_back(WorkerPool.EnqueueTask(
+			std::packaged_task<void()>{[&]() {
+				m_TinyStrategy.Initialize(m_Config.RootDirectory, "tobs", 1u << 28, 16, IsNewStore);  // 256 Mb per block
+			}},
+			WorkerThreadPool::EMode::DisableBacklog));
+		Work.emplace_back(WorkerPool.EnqueueTask(
+			std::packaged_task<void()>{[&]() {
+				m_SmallStrategy.Initialize(m_Config.RootDirectory, "sobs", 1u << 30, 4096, IsNewStore);	 // 1 Gb per block
+			}},
+			WorkerThreadPool::EMode::DisableBacklog));
 		for (std::future<void>& Result : Work)
 		{
 			if (Result.valid())