From 29736c4fed154233a8adbf93b29995c8e0b3ea78 Mon Sep 17 00:00:00 2001
From: Stefan Boberg <stefan.boberg@epicgames.com>
Date: Mon, 20 Apr 2026 21:22:01 +0200
Subject: Use eastl::deque for queues with many small elements (#991)
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Switch several deque-based queues from `std::deque` to `eastl::deque` to reduce per-element heap allocation overhead. MSVC's `std::deque` allocates one node per element for anything larger than ~16 bytes; `eastl::deque` groups 4, 8, or 32 elements per block depending on element size.

Converted call sites:
- `BlockingQueue` and `WorkerThreadPool` (generic — downstream callers benefit automatically)
- Session log entry buffer (~10k-entry ring of large log records — 4 per block vs 1)
- Job queue (`Ref<Job>` — 32 per block vs 2)
- RPC recording request queue (large `QueuedRequest` struct — 4 per block vs 1)
- StatsD client message queues (~32-byte buffers — 8 per block vs 1)
---
 src/zencore/workthreadpool.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

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

diff --git a/src/zencore/workthreadpool.cpp b/src/zencore/workthreadpool.cpp
index 1cb338c66..fb7edb2bd 100644
--- a/src/zencore/workthreadpool.cpp
+++ b/src/zencore/workthreadpool.cpp
@@ -4,6 +4,10 @@
 
 #include <zencore/blockingqueue.h>
 #include <zencore/except.h>
+
+ZEN_THIRD_PARTY_INCLUDES_START
+#include <EASTL/deque.h>
+ZEN_THIRD_PARTY_INCLUDES_END
 #include <zencore/logging.h>
 #include <zencore/scopeguard.h>
 #include <zencore/string.h>
@@ -56,8 +60,8 @@ struct WorkerThreadPool::Impl
 	std::atomic<size_t> m_WorkerThreadCounter{0};
 	std::atomic<int>	m_FreeWorkerCount{0};
 
-	mutable RwLock		   m_QueueLock;
-	std::deque<Ref<IWork>> m_WorkQueue;
+	mutable RwLock			 m_QueueLock;
+	eastl::deque<Ref<IWork>> m_WorkQueue;
 
 	Impl(int InThreadCount, std::string_view WorkerThreadBaseName)
 	: m_ThreadCount(InThreadCount)
-- 
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