Configuring Pile-up Digitization to run in AthenaMT should cause the job to bail

Digitization configuration should throw a RuntimeError if a pile-up digitization
job is configured to be run with AthenaMT. This configuration is not currently
supported. See discussion in ATLASRECTS-6129.

Simulation/Digitization/python/DigitizationSteering.py

@@ -22,10 +22,16 @@ from SCT_Digitization.SCT_DigitizationConfigNew import SCT_DigitizationCfg
 from TileSimAlgs.TileDigitizationConfig import TileDigitizationCfg, TileTriggerDigitizationCfg
 from TRT_Digitization.TRT_DigitizationConfigNew import TRT_DigitizationCfg
 
+from AthenaCommon.Logging import logging
+logDigiSteering = logging.getLogger('DigitizationSteering')
 
 def DigitizationMainServicesCfg(flags):
     """Configure main digitization services"""
     if flags.Digitization.PileUp:
+        if flags.Concurrency.NumThreads > 0:
+            logDigiSteering.error("DigitizationMainServicesCfg: Attempting to run pile-up digitization AthenaMT using %s threads!", str(flags.Concurrency.NumThreads))
+            logDigiSteering.error("DigitizationMainServicesCfg: Running pile-up digitization with AthenaMT is not supported. Please update your configuration. The job will fail now.")
+            raise RuntimeError("DigitizationSteering.DigitizationMainServicesCfg: Running pile-up digitization with AthenaMT is not supported. Please update your configuration.")
         from Digitization.PileUpConfigNew import PileUpEventLoopMgrCfg
         acc = MainServicesCfg(flags, LoopMgr="PileUpEventLoopMgr")
         acc.merge(PileUpEventLoopMgrCfg(flags))

Simulation/Digitization/share/ConfigDigitization.py

@@ -75,6 +75,11 @@ if DetFlags.pileup.any_on() or digitizationFlags.doXingByXingPileUp():
     # protection for SteppingCache usage - currently incompatible with PileUpTools
     if digitizationFlags.SignalPatternForSteppingCache.statusOn and digitizationFlags.doXingByXingPileUp():
         raise RuntimeError("SteppingCache is incompatible with PileUpTools. Please switch off either digitizationFlags.SignalPatternForSteppingCache or digitizationFlags.doXingByXingPileUp.")
+    from AthenaCommon.ConcurrencyFlags import jobproperties as jp
+    if jp.ConcurrencyFlags.NumThreads() > 0:
+        logConfigDigitization.error("Attempting to run pile-up digitization AthenaMT using %s threads!", str(jp.ConcurrencyFlags.NumThreads()))
+        logConfigDigitization.error("Running pile-up digitization with AthenaMT is not supported. Please update your configuration. The job will fail now.")
+        raise RuntimeError("Running pile-up digitization with AthenaMT is not supported. Please update your configuration.")
     include( "Digitization/ConfigPileUpEventLoopMgr.py" )
 if DetFlags.pileup.any_on():
     logConfigDigitization.info("PILEUP CONFIGURATION:")