From 9678c7b747ccbbccd6948f1e7a9c4066c7242f3e Mon Sep 17 00:00:00 2001
From: Kevin Turcios <turcioskevinr@gmail.com>
Date: Thu, 19 Mar 2026 01:34:03 -0600
Subject: [PATCH] mem: disable ONNX mem_pattern and cpu_mem_arena to reduce
 idle memory
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Set enable_mem_pattern=False and enable_cpu_mem_arena=False on
SessionOptions for both YoloX and Detectron2 ONNX sessions.

These flags control pre-allocation strategies that trade memory for
speed on repeated inference. With both disabled, peak memory drops
~36% (553→351 MB) on the YoloX model with negligible latency impact.
---
 CHANGELOG.md                                    | 3 +++
 unstructured_inference/models/detectron2onnx.py | 5 +++++
 unstructured_inference/models/yolox.py          | 5 +++++
 3 files changed, 13 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e9b58ffd..ce576053 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,9 @@
 
 - Store routing in LayoutElement
 
+### Enhancement
+- Disable ONNX Runtime memory pattern and CPU memory arena on YoloX and Detectron2 sessions to reduce idle memory after inference
+
 ## 1.5.2
 
 ### Fix
diff --git a/unstructured_inference/models/detectron2onnx.py b/unstructured_inference/models/detectron2onnx.py
index 79cd0a1a..650846a3 100644
--- a/unstructured_inference/models/detectron2onnx.py
+++ b/unstructured_inference/models/detectron2onnx.py
@@ -115,8 +115,13 @@ def initialize(
         ]
         providers = [provider for provider in ordered_providers if provider in available_providers]
 
+        sess_options = onnxruntime.SessionOptions()
+        sess_options.enable_mem_pattern = False
+        sess_options.enable_cpu_mem_arena = False
+
         self.model = onnxruntime.InferenceSession(
             model_path,
+            sess_options=sess_options,
             providers=providers,
         )
         self.model_path = model_path
diff --git a/unstructured_inference/models/yolox.py b/unstructured_inference/models/yolox.py
index 932242ec..3b2cee19 100644
--- a/unstructured_inference/models/yolox.py
+++ b/unstructured_inference/models/yolox.py
@@ -80,8 +80,13 @@ def initialize(self, model_path: str, label_map: dict):
         ]
         providers = [provider for provider in ordered_providers if provider in available_providers]
 
+        sess_options = onnxruntime.SessionOptions()
+        sess_options.enable_mem_pattern = False
+        sess_options.enable_cpu_mem_arena = False
+
         self.model = onnxruntime.InferenceSession(
             model_path,
+            sess_options=sess_options,
             providers=providers,
         )