Use TBB_NUM_THREADS in addition to OMP_NUM_THREADS

Suggested by David Rohr. Hoping to fix a rare crash in trdreco2.
Seems to work better indeed in local tests.

Author: sawenzel

MC/bin/o2dpg_sim_workflow.py

@@ -1143,7 +1143,7 @@ def getDigiTaskName(det):
        tpcclussect = createTask(name=taskname, needs=tpcclusterneed, tf=tf, cwd=timeframeworkdir, lab=["RECO"], cpu='2', mem='8000')
        digitmergerstr = '${O2_ROOT}/bin/o2-tpc-chunkeddigit-merger --tpc-sectors ' + str(s)+'-'+str(s+sectorpertask-1) + ' --tpc-lanes ' + str(NWORKERS_TF) + ' | '
        tpcclussect['cmd'] = (digitmergerstr,'')[args.no_tpc_digitchunking] + ' ${O2_ROOT}/bin/o2-tpc-reco-workflow ' + getDPL_global_options(bigshm=True) + ' --input-type ' + ('digitizer','digits')[args.no_tpc_digitchunking] + ' --output-type clusters,send-clusters-per-sector --tpc-native-cluster-writer \" --outfile tpc-native-clusters-part'+ str((int)(s/sectorpertask)) + '.root\" --tpc-sectors ' + str(s)+'-'+str(s+sectorpertask-1) + ' ' + putConfigValues(["GPU_global"], {"GPU_proc.ompThreads" : 4}) + ('',' --disable-mc')[args.no_mc_labels]
-       tpcclussect['env'] = { "OMP_NUM_THREADS" : "4" }
+       tpcclussect['env'] = { "OMP_NUM_THREADS" : "4" , "TBB_NUM_THREADS" : "4" }
        tpcclussect['semaphore'] = "tpctriggers.root"
        tpcclussect['retry_count'] = 2  # the task has a race condition --> makes sense to retry
        workflow['stages'].append(tpcclussect)