Implemented the memory fix.

Changed app.py:
•
process_pft_pdf() now uses the uploaded file stream directly instead of copying the PDF into bytes.
•
Output now uses SpooledTemporaryFile, so larger generated PDFs spill to disk instead of staying fully in RAM.
•
Explicitly closes PdfReader objects after writing.
•
Removed @app.teardown_request gc.collect(), which was running too early and could break send_file.
•
Added response.call_on_close() cleanup so the generated PDF stream is closed only after Flask/Werkzeug finishes sending it.
Changed Dockerfile:
•
Added Gunicorn --max-requests 50 --max-requests-jitter 10 as a production guardrail against PDF-library or allocator memory growth.

app.py

@@ -2,15 +2,15 @@ import sys
 import gc
 import re
 import json
-import io
 import logging
+import tempfile
 from pathlib import Path
 from datetime import datetime
 import pdfplumber
 from pypdf import PdfReader, PdfWriter
 from pypdf.constants import UserAccessPermissions
 from pypdf.generic import NameObject, BooleanObject
-from typing import TypedDict, Literal
+from typing import BinaryIO, TypedDict, Literal
 from flask import Flask, request, send_file, abort
 from werkzeug.utils import secure_filename
 
@@ -45,7 +45,7 @@ class ParsedPdfData(TypedDict):
     highlighted_box: InterpretationType
 
 
-def process_pft_pdf(input_bytes: bytes) -> io.BytesIO:
+def process_pft_pdf(input_stream: BinaryIO) -> BinaryIO:
     text_mapping: dict[str, InterpretationType] = {
         "normal": "normal",
         "pv disorders": "pvd",
@@ -70,8 +70,11 @@ def process_pft_pdf(input_bytes: bytes) -> io.BytesIO:
         "highlighted_box": "normal"
     }
 
-    # Use a detached context for pdfplumber to read the file metadata
-    with pdfplumber.open(io.BytesIO(input_bytes)) as pdf:
+    input_stream.seek(0)
+
+    # Use the upload stream directly so each request does not duplicate the PDF
+    # in memory before parsing.
+    with pdfplumber.open(input_stream) as pdf:
         if len(pdf.pages) < 2:
             logger.error(
                 "Expected a 2-page PFT report, found %s page(s).", len(pdf.pages))
@@ -82,18 +85,17 @@ def process_pft_pdf(input_bytes: bytes) -> io.BytesIO:
         page2 = pdf.pages[1]
 
         # --- 1. FULL TEXT METADATA EXTRACTION (Page 1) ---
-        full_text_p1 = page1.extract_text()
+        full_text_p1 = page1.extract_text() or ""
 
-        if full_text_p1:
-            lines = [line.strip()
-                     for line in full_text_p1.split("\n") if line.strip()]
-            for line in lines:
-                if "ID: #" in line:
-                    record["patient_name"] = line.split("ID:")[0].strip()
-                    dob_match = re.search(r"\((\d{1,2}/\d{1,2}/\d{4})\)", line)
-                    if dob_match:
-                        record["date_of_birth"] = dob_match.group(1)
-                    break
+        lines = [line.strip()
+                 for line in full_text_p1.split("\n") if line.strip()]
+        for line in lines:
+            if "ID: #" in line:
+                record["patient_name"] = line.split("ID:")[0].strip()
+                dob_match = re.search(r"\((\d{1,2}/\d{1,2}/\d{4})\)", line)
+                if dob_match:
+                    record["date_of_birth"] = dob_match.group(1)
+                break
 
         dos_match = re.search(
             r"Test Date:\s*(\d{1,2}/\d{1,2}/\d{4})", full_text_p1)
@@ -106,11 +108,11 @@ def process_pft_pdf(input_bytes: bytes) -> io.BytesIO:
             record["smoker"] = smoker_match.group(1).capitalize()
 
         # --- 2. INTERPRETATION DIAGRAM PROCESSING (Page 2) ---
-        text_p2 = page2.extract_text()
+        text_p2 = page2.extract_text() or ""
         detected_box: InterpretationType = "normal"
         box_found = False
 
-        if text_p2 and "System Summary Interpretation" in text_p2:
+        if "System Summary Interpretation" in text_p2:
             summary_text = text_p2.split(
                 "System Summary Interpretation")[-1].strip().lower()
             for phrase, token in text_mapping.items():
@@ -154,99 +156,106 @@ def process_pft_pdf(input_bytes: bytes) -> io.BytesIO:
             f"Template file '{TEMPLATE_NAME}' missing inside container workspace.")
 
     writer = PdfWriter()
-
     template_reader = PdfReader(TEMPLATE_NAME)
-    writer.append(template_reader)
-
-    patient_data = {"patient_name": "",
-                    "date_of_service": "", "date_of_birth": ""}
-    check_boxes = {
-        "results_cw_neuro_disorder": "/Off", "results_ild_pn": "/Off", "results_asthma_cb": "/Off",
-        "results_emphysema": "/Off", "refer_pulmo": "/Off", "refer_smoking": "/Off",
-        "results_pvd": "/Off", "results_normal": "/Off"
-    }
-
-    formatted_dos = datetime.strptime(record.get(
-        "date_of_service"), "%m/%d/%Y").strftime("%m/%d/%Y") if record.get("date_of_service") else ""
-    formatted_dob = datetime.strptime(record.get(
-        "date_of_birth"), "%m/%d/%Y").strftime("%m/%d/%Y") if record.get("date_of_birth") else ""
-
-    patient_data |= {
-        "patient_name": record.get("patient_name").title() if record.get("patient_name") else "",
-        "date_of_service": formatted_dos,
-        "date_of_birth": formatted_dob,
-    }
-
-    check_boxes |= {
-        "refer_smoking": "/Yes" if record.get("smoker") == "Yes" else "/Off"}
-
-    match record["highlighted_box"]:
-        case "normal":
-            check_boxes |= {"results_normal": "/Yes"}
-        case "pvd":
-            check_boxes |= {"results_pvd": "/Yes", "refer_pulmo": "/Yes"}
-        case "cw_neuro_disorder":
-            check_boxes |= {
-                "results_cw_neuro_disorder": "/Yes", "refer_pulmo": "/Yes"}
-        case "ild_pn":
-            check_boxes |= {"results_ild_pn": "/Yes", "refer_pulmo": "/Yes"}
-        case "asthma_cb":
-            check_boxes |= {"results_asthma_cb": "/Yes", "refer_pulmo": "/Yes"}
-        case "emphysema":
-            check_boxes |= {"results_emphysema": "/Yes", "refer_pulmo": "/Yes"}
-
-    form_data = patient_data | check_boxes
-
-    writer.get_fields()
-
-    writer.update_page_form_field_values(
-        writer.pages[0],
-        form_data,
-        auto_regenerate=False,
-        flatten=True
-    )
-
-    for page in writer.pages:
-        if "/Annots" in page:
-            for annot in page["/Annots"]:
-                annot_obj = annot.get_object()
-                if annot_obj.get("/t") in check_boxes:
-                    field_name = annot_obj["/T"]
-                    target_value = check_boxes[field_name]
-                    annot_obj.update({
-                        NameObject("/V"): NameObject(target_value),
-                        NameObject("/AS"): NameObject(target_value)
-                    })
+    raw_results_reader: PdfReader | None = None
 
     try:
-        writer.set_need_appearances_writer()
-    except AttributeError:
-        if "/AcroForm" in writer._root_object:
-            writer._root_object["/AcroForm"].update({
-                NameObject("/NeedAppearances"): BooleanObject(True)
-            })
+        writer.append(template_reader)
 
-    # Strip widget annotations
-    writer.remove_annotations(subtypes="/Widget")
+        patient_data = {"patient_name": "",
+                        "date_of_service": "", "date_of_birth": ""}
+        check_boxes = {
+            "results_cw_neuro_disorder": "/Off", "results_ild_pn": "/Off", "results_asthma_cb": "/Off",
+            "results_emphysema": "/Off", "refer_pulmo": "/Off", "refer_smoking": "/Off",
+            "results_pvd": "/Off", "results_normal": "/Off"
+        }
 
-    # Append raw input pages directly onto the end of our current working context
-    raw_results_reader = PdfReader(io.BytesIO(input_bytes))
-    writer.append(raw_results_reader)
+        formatted_dos = datetime.strptime(record.get(
+            "date_of_service"), "%m/%d/%Y").strftime("%m/%d/%Y") if record.get("date_of_service") else ""
+        formatted_dob = datetime.strptime(record.get(
+            "date_of_birth"), "%m/%d/%Y").strftime("%m/%d/%Y") if record.get("date_of_birth") else ""
 
-    # Secure document permissions
-    permissions = UserAccessPermissions.PRINT | UserAccessPermissions.EXTRACT
-    owner_pw = "heather"
+        patient_data |= {
+            "patient_name": record.get("patient_name").title() if record.get("patient_name") else "",
+            "date_of_service": formatted_dos,
+            "date_of_birth": formatted_dob,
+        }
 
-    writer.encrypt(
-        user_password="",
-        owner_password=owner_pw,
-        permissions_flag=permissions
-    )
+        check_boxes |= {
+            "refer_smoking": "/Yes" if record.get("smoker") == "Yes" else "/Off"}
 
-    # Output final joined stream directly to Flask
-    output_stream = io.BytesIO()
-    writer.write(output_stream)
-    output_stream.seek(0)
+        match record["highlighted_box"]:
+            case "normal":
+                check_boxes |= {"results_normal": "/Yes"}
+            case "pvd":
+                check_boxes |= {"results_pvd": "/Yes", "refer_pulmo": "/Yes"}
+            case "cw_neuro_disorder":
+                check_boxes |= {
+                    "results_cw_neuro_disorder": "/Yes", "refer_pulmo": "/Yes"}
+            case "ild_pn":
+                check_boxes |= {"results_ild_pn": "/Yes", "refer_pulmo": "/Yes"}
+            case "asthma_cb":
+                check_boxes |= {"results_asthma_cb": "/Yes", "refer_pulmo": "/Yes"}
+            case "emphysema":
+                check_boxes |= {"results_emphysema": "/Yes", "refer_pulmo": "/Yes"}
+
+        form_data = patient_data | check_boxes
+
+        writer.get_fields()
+
+        writer.update_page_form_field_values(
+            writer.pages[0],
+            form_data,
+            auto_regenerate=False,
+            flatten=True
+        )
+
+        for page in writer.pages:
+            if "/Annots" in page:
+                for annot in page["/Annots"]:
+                    annot_obj = annot.get_object()
+                    if annot_obj.get("/t") in check_boxes:
+                        field_name = annot_obj["/T"]
+                        target_value = check_boxes[field_name]
+                        annot_obj.update({
+                            NameObject("/V"): NameObject(target_value),
+                            NameObject("/AS"): NameObject(target_value)
+                        })
+
+        try:
+            writer.set_need_appearances_writer()
+        except AttributeError:
+            if "/AcroForm" in writer._root_object:
+                writer._root_object["/AcroForm"].update({
+                    NameObject("/NeedAppearances"): BooleanObject(True)
+                })
+
+        # Strip widget annotations
+        writer.remove_annotations(subtypes="/Widget")
+
+        # Append raw input pages directly onto the end of our current working context
+        input_stream.seek(0)
+        raw_results_reader = PdfReader(input_stream)
+        writer.append(raw_results_reader)
+
+        # Secure document permissions
+        permissions = UserAccessPermissions.PRINT | UserAccessPermissions.EXTRACT
+        owner_pw = "heather"
+
+        writer.encrypt(
+            user_password="",
+            owner_password=owner_pw,
+            permissions_flag=permissions
+        )
+
+        # Keep small responses in memory, but spill larger PDFs to a temp file.
+        output_stream = tempfile.SpooledTemporaryFile(max_size=8 * 1024 * 1024, mode="w+b")
+        writer.write(output_stream)
+        output_stream.seek(0)
+    finally:
+        template_reader.close()
+        if raw_results_reader is not None:
+            raw_results_reader.close()
 
     logger.info("PDTR successfully prepended to PFT result PDF.")
     return output_stream
@@ -268,20 +277,24 @@ def upload_file():
         logger.info("Received PDF: %s", original_filename)
 
         try:
-            # Read input file directly into memory bytes
-            raw_input_bytes = file.read()
-
-            # Execute logic sequentially
-            processed_file_stream = process_pft_pdf(raw_input_bytes)
+            # Execute logic sequentially using the upload stream directly.
+            processed_file_stream = process_pft_pdf(file.stream)
 
             logger.info("Returning processed PDF file: %s", original_filename)
-            return send_file(
+            response = send_file(
                 processed_file_stream,
                 mimetype='application/pdf',
                 as_attachment=True,
                 download_name=original_filename
             )
 
+            @response.call_on_close
+            def close_processed_file_stream() -> None:
+                processed_file_stream.close()
+                gc.collect()
+
+            return response
+
         except Exception as e:
             logger.exception("Error during execution processing pipeline")
             return abort(500, f"Error processing file: {str(e)}")
@@ -323,12 +336,5 @@ def index():
     """
 
 
-@app.teardown_request
-def spi_clear_memory(exception=None):
-    """Runs automatically after every single request."""
-    # Force collection of unreferenced objects
-    gc.collect()
-
-
 if __name__ == "__main__":
     app.run(host='0.0.0.0', port=5000)