d

app.py

@@ -33,6 +33,9 @@ printer_model = "QL-1100"
 backend = 'pyusb'
 printer = 'usb://0x04f9:0x20a7'
 
+# Create a lock to manage printer access
+printer_lock = threading.Lock()
+
 # Convert PDF to image
 def convert_pdf_to_image(pdf_path):
     """Converts a PDF to a PIL Image"""
@@ -76,17 +79,22 @@ def print_address_label(pdf_path):
             cut=True
         )
 
-        app.logger.info("Sending to printer...")
-        send(
-            instructions=instructions, 
-            printer_identifier=printer, 
-            backend_identifier=backend, 
-            blocking=True
-        )
-        app.logger.info("Print job sent successfully")
+        app.logger.info("Waiting to acquire printer lock...")
+        with printer_lock:  # Ensure only one thread sends a job at a time
+            app.logger.info("Sending to printer...")
+            try:
+                send(
+                    instructions=instructions, 
+                    printer_identifier=printer, 
+                    backend_identifier=backend, 
+                    blocking=True
+                )
+                app.logger.info("Print job sent successfully")
+            except Exception as e:
+                app.logger.error(f"Error during printing: {str(e)}")
         
     except Exception as e:
-        app.logger.error(f"Error during printing: {str(e)}")
+        app.logger.error(f"Error during label printing: {str(e)}")
 
 # Worker thread that processes files from the queue
 def process_queue():