refactor: move kitchen printer socket communication to an isolated thread to improve reliability and performance

models/pos_printer.py

@@ -5,6 +5,29 @@ from odoo import models, fields, api, _
 
 _logger = logging.getLogger(__name__)
 
+def _isolated_printer_thread(ip, data):
+    """
+    Completely isolated printer thread. 
+    Does not touch Odoo environment to avoid GIL/Locking issues.
+    """
+    s = None
+    try:
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        # 2 seconds is enough for a local network printer. 
+        # Reducing from 5s to avoid holding resources too long.
+        s.settimeout(2.0) 
+        s.connect((ip, 9100))
+        s.sendall(data)
+        _logger.info("POS_PRINTER: Successfully printed to %s", ip)
+    except Exception as e:
+        _logger.error("POS_PRINTER: Background print failed for IP %s: %s", ip, e)
+    finally:
+        if s:
+            try:
+                s.close()
+            except:
+                pass
+
 class PosPrinter(models.Model):
     _inherit = 'pos.printer'
 
@@ -28,26 +51,14 @@ class PosPrinter(models.Model):
     @api.model
     def print_network_kitchen_receipt(self, printer_id, receipt_data):
         """
-        Receives structural receipt_data from POS frontend and sends ESC/POS string to network printer.
-        Optimized to use background threading to prevent blocking the POS transaction/RPC.
+        Receives structural receipt_data and sends to background worker.
         """
         printer = self.browse(printer_id)
         if not printer or not printer.network_printer_ip:
             return {'successful': False, 'message': 'Printer IP not configured'}
 
-        # Start printing in a background thread to avoid POS timeout
-        # We don't need a new cursor here as we've already browsed the printer
-        # and we don't write to the database in the thread.
-        thread = threading.Thread(target=self._threaded_print, args=(printer.network_printer_ip, receipt_data))
-        thread.daemon = True # Ensure thread doesn't block server shutdown
-        thread.start()
-        
-        return {'successful': True, 'message': 'Print job sent to background queue'}
-
-    def _threaded_print(self, ip, receipt_data):
-        """Perform the actual socket communication in the background."""
+        # Build the ESC/POS data in the main thread (fast)
         try:
-            # Build basic ESC/POS commands
             ESC = b'\x1b'
             GS = b'\x1d'
             INIT = ESC + b'@'
@@ -92,12 +103,12 @@ class PosPrinter(models.Model):
 
             data += b"-" * 32 + NEWLINE + NEWLINE + NEWLINE + CUT
 
-            # Send to printer
-            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-            s.settimeout(5.0) # Slightly longer timeout for background print
-            s.connect((ip, 9100))
-            s.sendall(data)
-            s.close()
-            _logger.info("Successfully printed to kitchen printer at %s", ip)
+            # Start thread
+            t = threading.Thread(target=_isolated_printer_thread, args=(printer.network_printer_ip, data))
+            t.daemon = True
+            t.start()
+            
+            return {'successful': True, 'message': 'Print job sent to background queue'}
         except Exception as e:
-            _logger.error("Background kitchen print failed for IP %s: %s", ip, e)
+            _logger.error("POS_PRINTER: Failed to build print data: %s", e)
+            return {'successful': False, 'message': str(e)}