diff --git a/fuzzers/wcet_qemu_sys/Makefile b/fuzzers/wcet_qemu_sys/Makefile
index dace03ae5d..c1e58ecbab 100644
--- a/fuzzers/wcet_qemu_sys/Makefile
+++ b/fuzzers/wcet_qemu_sys/Makefile
@@ -4,10 +4,18 @@ TARGET_TRACE = $(BENCHDIR)/traces/tmr_worst.ron
 TARGET_EDGES = $(BENCHDIR)/edges/tmr_worst.ron
 RUNTIME = 3600
 COMMON_FLAGS = benchmark,dump_infos,fuzz_interrupt
+NUM_JOB = 3
+NUM_ITERATIONS = 10
+LOCKFILE = /tmp/bench_sem
+LOCK = ./bash_sem.sh $(LOCKFILE) lock
+RELEASE = ./bash_sem.sh $(LOCKFILE) release
 
 $(BENCHDIR)/bin:
 	mkdir -p $@
 
+$(BENCHDIR)/target_random:
+	cargo build --bin fuzzer --target-dir $@ --features benchmark,dump_infos,fuzz_interrupt,sched_queue,fuzz_random
+
 $(BENCHDIR)/target_known_edges:
 	cargo build --bin fuzzer --target-dir $@ --features $(COMMON_FLAGS),feed_known_edges,sched_queue
 
@@ -41,21 +49,23 @@ $(BENCHDIR)/target_graph_muta_afl:
 $(BENCHDIR)/target_graph_all:
 	cargo build --bin fuzzer --target-dir $@ --features $(COMMON_FLAGS),feed_graph,sched_graph,feed_afl,muta_snip,muta_input,muta_suffix,muta_interrupt
 
-binaries: $(BENCHDIR)/target_known_edges $(BENCHDIR)/target_afl_queue $(BENCHDIR)/target_afl_mapmax $(BENCHDIR)/target_state $(BENCHDIR)/target_state_afl $(BENCHDIR)/target_state_afl_int \
+binaries: $(BENCHDIR)/target_random $(BENCHDIR)/target_known_edges $(BENCHDIR)/target_afl_queue $(BENCHDIR)/target_afl_mapmax $(BENCHDIR)/target_state $(BENCHDIR)/target_state_afl $(BENCHDIR)/target_state_afl_int \
 	$(BENCHDIR)/target_graph $(BENCHDIR)/target_graph_muta $(BENCHDIR)/target_graph_afl $(BENCHDIR)/target_graph_muta_afl $(BENCHDIR)/target_graph_all
 
 # variants: known_edges, afl_queue, afl_mapmax, state, state_afl, graph, graph_muta, graph_afl, graph_all
 $(BENCHDIR)/bench_%.log: $(BENCHDIR)/target_% $(TARGET_TRACE)
 	mkdir -p $(BENCHDIR)/execs
-	for i in {1..10}; do \
+	for i in {1..$(NUM_ITERATIONS)}; do \
 		CASE=$$(basename -s.log $@ | cut -d'_' -f 2- ); \
 		[ -f $(BENCHDIR)/execs/$$CASE\_$$i.exec -a -f $@_$$i ] && continue; \
+		$(LOCK); \
 		echo $$CASE iteration $$i; \
 		mkdir -p $(BENCHDIR)/infos/$$CASE ; \
 		./fuzzer_bench.sh $</debug/fuzzer $(TARGET) --libafl-traces $(TARGET_TRACE) --libafl-fuzztime $(RUNTIME) \
 			--libafl-dump $(BENCHDIR)/infos/$$CASE/$$i \
-			--libafl-edges $(TARGET_EDGES) --libafl-exectimes $(BENCHDIR)/execs/$$CASE\_$$i.exec > $@_$$i; \
-		sed -i "1 i\\$$CASE " $(BENCHDIR)/execs/$$CASE\_$$i.exec; \
+			--libafl-edges $(TARGET_EDGES) --libafl-exectimes $(BENCHDIR)/execs/$$CASE\_$$i.exec > $@_$$i || \
+		sed -i "1 i\\$$CASE " $(BENCHDIR)/execs/$$CASE\_$$i.exec || \
+		$(RELEASE) & \
 		done
 	for i in $@_*; do tail -n 1 $$i >> $@; done
 
@@ -64,6 +74,8 @@ benchmarks_all: target/bench/bench_known_edges.log target/bench/bench_afl_queue.
 
 benchmarks_int_mut: target/bench/bench_graph_muta_afl.log target/bench/bench_graph_all.log target/bench/bench_state_afl.log target/bench/bench_state_afl_int.log
 
+benchmark_random: target/bench/bench_random.log
+
 all: binaries benchmarks_all
 
 clean_bench:
@@ -74,6 +86,12 @@ clean_aggregate:
 
 clean:
 	rm -rf target/bench
+	echo $(NUM_JOB)	> $(LOCKFILE)
+	rm -rf $(LOCKFILE)_lockdir
+
+reset_sem:
+	echo $(NUM_JOB)	> $(LOCKFILE)
+	rm -rf $(LOCKFILE)_lockdir
 	
 %.case: %_inputs
 	mkdir -p $(BENCHDIR)/traces $(BENCHDIR)/edges
diff --git a/fuzzers/wcet_qemu_sys/bash_sem.sh b/fuzzers/wcet_qemu_sys/bash_sem.sh
new file mode 100755
index 0000000000..c93986b563
--- /dev/null
+++ b/fuzzers/wcet_qemu_sys/bash_sem.sh
@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+# A generic counting semaphore in bash
+# Parameter is the lockfile and operation
+# Setup:
+# rm /tmp/test
+# echo $num > /tmp/test
+
+set -e
+if [[ ! -f $1 ]]; then echo "Parameter 1: File Does not exist"; exit; fi
+if [[ $2 != "lock" ]] && [[ $2 != "release" ]]; then echo "Parameter 2: must be lock or release"; exit; fi
+if [[ $2 = "lock" ]]; then
+	SEM=''
+	while [[ -z $SEM ]]; do
+		if mkdir $1_lockdir > /dev/null 2>&1 ; then
+			VAL=$(cat $1)
+			if (( $VAL > 0 ))
+			then
+				SEM=$(sed -i "s@$VAL@$(( $VAL - 1))@w /dev/stdout" $1)
+				echo "Take $VAL -> $SEM"
+			else
+				sleep 1; wait
+			fi
+		else
+			sleep 0.1;
+		fi
+	done
+	rmdir $1_lockdir
+else
+	SEM=''
+	while [[ -z $SEM ]]; do
+		if mkdir $1_lockdir > /dev/null 2>&1 ; then
+			VAL=$(cat $1)
+			SEM=$(sed -i "s@$VAL@$(( $VAL + 1))@w /dev/stdout" $1)
+			echo "Give $VAL -> $(( $VAL + 1 ))"
+		else
+			sleep 0.1;
+		fi
+	done
+	rmdir $1_lockdir
+fi
+
+#SEM=''; while [[ -z SEM ]]; do VAL=$(cat /tmp/test); if (( $VAL > 0 )); then SEM=$(sed -i "s@$VAL@$(( $VAL - 1))@w /dev/stdout" /tmp/test); else sleep 1; wait; fi; done