From: Kienan Stewart <kstewart@efficios.com>
Date: Thu, 14 Nov 2024 19:28:06 +0000 (-0500)
Subject: Tests: Wait for specific PIDs of background applications
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=faaa11c1e04c5e11d94d3a920d32d72149402e25;p=lttng-tools.git

Tests: Wait for specific PIDs of background applications

When running lttng-relayd or any other SUT from utils.sh in a fashion
that doesn't take it out of the test's process tree (e.g. when started
without '-d' or '-b'), `wait` will hang on those processes are well.

Change-Id: I82e0365d5165088980c0fce8e451fa0557ee201a
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/tests/destructive/metadata-regeneration b/tests/destructive/metadata-regeneration
index 5daa21b16..23c216e54 100755
--- a/tests/destructive/metadata-regeneration
+++ b/tests/destructive/metadata-regeneration
@@ -126,7 +126,7 @@ function test_ust_local ()
 
 	touch "${file_sync_before_last}"
 	# Wait for the applications started in background
-	wait
+	wait "${!}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	validate_trace_date $DATE1 "$TRACE_PATH"
@@ -168,7 +168,7 @@ function test_ust_streaming ()
 	touch "${file_sync_before_last}"
 
 	# Wait for the applications started in background
-	wait
+	wait "${!}"
 	stop_lttng_tracing_ok $SESSION_NAME
 	validate_trace_date $DATE1 $TRACE_PATH/$HOSTNAME/$SESSION_NAME*
 
diff --git a/tests/regression/tools/exclusion/test_exclusion b/tests/regression/tools/exclusion/test_exclusion
index 69347a2b2..0dead2096 100755
--- a/tests/regression/tools/exclusion/test_exclusion
+++ b/tests/regression/tools/exclusion/test_exclusion
@@ -122,6 +122,7 @@ function test_exclusion_tracing_started
 	$TESTAPP_BIN -i 1 -w 10000 \
 		--create-in-main ${file_create_in_main} \
 		--wait-before-first-event ${file_wait_before_first} 2>&1 &
+	tracee_pids+=("${!}")
 
 	while [ ! -f "${file_create_in_main}" ]; do
 		sleep 0.5
@@ -136,7 +137,8 @@ function test_exclusion_tracing_started
 	touch ${file_wait_before_first}
 
 	# Wait for the testapp to finish.
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok $SESSION_NAME
 
@@ -183,6 +185,7 @@ print_test_banner "$TEST_DESC"
 bail_out_if_no_babeltrace
 
 start_lttng_sessiond
+tracee_pids=()
 
 diag "Enable event without exclusion"
 dry_run
diff --git a/tests/regression/tools/live/test_ust_tracefile_count b/tests/regression/tools/live/test_ust_tracefile_count
index 3225b65d6..bf6d6d1d3 100755
--- a/tests/regression/tools/live/test_ust_tracefile_count
+++ b/tests/regression/tools/live/test_ust_tracefile_count
@@ -52,9 +52,7 @@ start_lttng_relayd_notap "-o $TRACE_PATH"
 
 setup_live_tracing
 
-# Run app in background
 $TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT --sync-after-first-event ${file_sync_after_first} >/dev/null 2>&1
-
 while [ ! -f "${file_sync_after_first}" ]; do
 	sleep 0.5
 done
@@ -62,9 +60,6 @@ done
 # Start the live test
 $TESTDIR/regression/tools/live/live_test
 
-# Wait for the applications started in background
-wait
-
 clean_live_tracing
 
 rm -f ${file_sync_after_first}
diff --git a/tests/regression/tools/mi/test_mi b/tests/regression/tools/mi/test_mi
index faeb3d09b..39f082e6c 100755
--- a/tests/regression/tools/mi/test_mi
+++ b/tests/regression/tools/mi/test_mi
@@ -538,6 +538,7 @@ function test_list_ust_event ()
 
 	local file_sync_after_first=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX")
 	local file_sync_before_last=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX")
+	local pid
 
 	OUTPUT_FILE="list_ust_event.xml"
 
@@ -548,6 +549,7 @@ function test_list_ust_event ()
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
 		--sync-after-first-event ${file_sync_after_first} \
 		--sync-before-last-event ${file_sync_before_last} & 2>/dev/null
+	pid="${!}"
 
 	while [ ! -f "${file_sync_after_first}" ]; do
 		sleep 0.5
@@ -577,8 +579,7 @@ function test_list_ust_event ()
 	test "$num" -ge "12"
 	ok $? "Mi test: $num / 12 ust event fields discovered"
 
-	#Wait for all background processes
-	wait
+	wait "${pid}"
 
 	rm -f ${file_sync_after_first}
 	rm -f ${file_sync_before_last}
diff --git a/tests/regression/tools/regen-metadata/test_ust b/tests/regression/tools/regen-metadata/test_ust
index a48221323..54931b720 100755
--- a/tests/regression/tools/regen-metadata/test_ust
+++ b/tests/regression/tools/regen-metadata/test_ust
@@ -42,6 +42,7 @@ function test_ust_streaming ()
 	local file_sync_after_first=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX")
 	local file_sync_before_last=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX")
 	local metadata_path
+	local pid
 
 	diag "Test UST streaming with metadata regeneration"
 	create_lttng_session_uri $SESSION_NAME net://localhost
@@ -50,13 +51,14 @@ function test_ust_streaming ()
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
 		--sync-after-first-event ${file_sync_after_first} \
 		--sync-before-last-event ${file_sync_before_last} >/dev/null 2>&1 &
+	pid="${!}"
 
 	start_lttng_tracing_ok $SESSION_NAME
 
 	touch ${file_sync_before_last}
 
 	# Wait for the applications started in background
-	wait
+	wait "${pid}"
 
 	# Expect a valid trace
 	stop_lttng_tracing_ok $SESSION_NAME
@@ -86,6 +88,7 @@ function test_ust_local ()
 	local file_sync_after_first=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX")
 	local file_sync_before_last=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX")
 	local metadata_path
+	local pid
 
 	diag "Test UST local with metadata regeneration"
 	create_lttng_session_ok $SESSION_NAME $TRACE_PATH
@@ -94,13 +97,14 @@ function test_ust_local ()
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
 		--sync-after-first-event ${file_sync_after_first} \
 		--sync-before-last-event ${file_sync_before_last} > /dev/null 2>&1 &
+	pid="${!}"
 
 	start_lttng_tracing_ok $SESSION_NAME
 
 	touch ${file_sync_before_last}
 
 	# Wait for the applications started in background
-	wait
+	wait "${pid}"
 
 	# Expect a valid trace
 	stop_lttng_tracing_ok $SESSION_NAME
@@ -129,6 +133,7 @@ function test_ust_pid ()
 {
 	local file_sync_after_first=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX")
 	local file_sync_before_last=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX")
+	local pid
 
 	diag "Test UST per-pid with metadata regeneration (expect failure)"
 	create_lttng_session_ok $SESSION_NAME $TRACE_PATH
@@ -138,13 +143,14 @@ function test_ust_pid ()
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
 		--sync-after-first-event ${file_sync_after_first} \
 		--sync-before-last-event ${file_sync_before_last} >/dev/null 2>&1 &
+	pid="${!}"
 
 	start_lttng_tracing_ok $SESSION_NAME
 
 	touch ${file_sync_before_last}
 
 	# Wait for the applications started in background
-	wait
+	wait "${pid}"
 	regenerate_metadata_fail $SESSION_NAME
 
 	stop_lttng_tracing_ok $SESSION_NAME
@@ -163,6 +169,7 @@ function test_ust_live ()
 {
 	local file_sync_after_first=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX")
 	local file_sync_before_last=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX")
+	local pid
 
 	diag "Test UST live with metadata regeneration (expect failure)"
 	create_lttng_session_uri $SESSION_NAME net://localhost --live
@@ -171,13 +178,14 @@ function test_ust_live ()
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
 		--sync-after-first-event ${file_sync_after_first} \
 		--sync-before-last-event ${file_sync_before_last} >/dev/null 2>&1 &
+	pid="${!}"
 
 	start_lttng_tracing_ok $SESSION_NAME
 
 	touch ${file_sync_before_last}
 
 	# Wait for the applications started in background
-	wait
+	wait "${pid}"
 	regenerate_metadata_fail $SESSION_NAME
 
 	stop_lttng_tracing_ok $SESSION_NAME
diff --git a/tests/regression/tools/relayd-grouping/test_ust b/tests/regression/tools/relayd-grouping/test_ust
index 8e2dca9cc..661565283 100755
--- a/tests/regression/tools/relayd-grouping/test_ust
+++ b/tests/regression/tools/relayd-grouping/test_ust
@@ -389,6 +389,7 @@ function test_ust_pid_streaming_snapshot ()
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
 		--sync-after-first-event "$file_sync_after_first" \
 		--sync-before-last-event "$file_sync_before_last" 2>&1 &
+	pid="${!}"
 
 	while [ ! -f "${file_sync_after_first}" ]; do
 		sleep 0.5
@@ -397,7 +398,7 @@ function test_ust_pid_streaming_snapshot ()
 	lttng_snapshot_record "$session_name"
 
 	touch "$file_sync_before_last"
-	wait
+	wait "${pid}"
 
 	stop_lttng_tracing_ok "$session_name"
 	destroy_lttng_session_ok "$session_name" --no-wait
diff --git a/tests/regression/tools/snapshots/ust_test b/tests/regression/tools/snapshots/ust_test
index e49549804..97f201442 100755
--- a/tests/regression/tools/snapshots/ust_test
+++ b/tests/regression/tools/snapshots/ust_test
@@ -63,10 +63,12 @@ function wait_test_apps()
 
 function stop_test_apps()
 {
-	diag "Stopping $TESTAPP_NAME"
-	kill "${APPS_PID[@]}"
-	wait "${APPS_PID[@]}"
-	APPS_PID=()
+	if [[ -n "${APPS_PID[*]}" ]]; then
+		diag "Stopping $TESTAPP_NAME"
+		kill "${APPS_PID[@]}"
+		wait "${APPS_PID[@]}"
+		APPS_PID=()
+	fi
 }
 
 function snapshot_add_output ()
diff --git a/tests/regression/tools/streaming/test_high_throughput_limits b/tests/regression/tools/streaming/test_high_throughput_limits
index cf3a40ddc..b8b01ccb8 100755
--- a/tests/regression/tools/streaming/test_high_throughput_limits
+++ b/tests/regression/tools/streaming/test_high_throughput_limits
@@ -105,6 +105,7 @@ function run_apps
 		# the status reply from the consumer quite slow thus delaying the
 		# registration done message.
 		LTTNG_UST_REGISTER_TIMEOUT=-1 $TESTAPP_BIN -i "$NR_ITER" >/dev/null 2>&1 &
+		tracee_pids+=("${!}")
 	done
 }
 
@@ -116,7 +117,8 @@ function test_high_throughput
 	start_lttng_tracing_ok $SESSION_NAME
 	run_apps
 	diag "Waiting for applications to end"
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 	pass "waiting done"
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -179,6 +181,7 @@ check_skip_kernel_test "$NUM_TESTS" "Skipping all tests." ||
 	trap interrupt_cleanup SIGTERM SIGINT
 
 	BW_LIMITS=(3200 400 100)
+	tracee_pids=()
 	for BW in "${BW_LIMITS[@]}";
 	do
 		diag "Test high-throughput with bandwidth limit set to ${BW}kbits"
diff --git a/tests/regression/tools/streaming/test_ust b/tests/regression/tools/streaming/test_ust
index 27f6b679b..80b461b34 100755
--- a/tests/regression/tools/streaming/test_ust
+++ b/tests/regression/tools/streaming/test_ust
@@ -31,6 +31,7 @@ fi
 function test_ust_before_start ()
 {
 	local file_sync_before_last=$(mktemp -u -t "tmp.test_${FUNCNAME[0]}_sync_before_last.XXXXXX")
+	local tracee_pids=()
 
 	diag "Test UST streaming BEFORE tracing starts"
 	create_lttng_session_uri $SESSION_NAME net://localhost
@@ -38,13 +39,14 @@ function test_ust_before_start ()
 
 	# Run 5 times with a 1 second delay
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT --sync-before-last-event ${file_sync_before_last} > /dev/null 2>&1 &
+	tracee_pids+=("${!}")
 
 	start_lttng_tracing_ok $SESSION_NAME
 
 	touch ${file_sync_before_last}
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -54,6 +56,7 @@ function test_ust_before_start ()
 function test_ust_after_start ()
 {
 	local file_sync_after_first=$(mktemp -u -t "tmp.test_${FUNCNAME[0]}_sync_after_first.XXXXXX")
+	local tracee_pids=()
 
 	diag "Test UST streaming AFTER tracing starts"
 	create_lttng_session_uri $SESSION_NAME net://localhost
@@ -62,7 +65,8 @@ function test_ust_after_start ()
 
 	# Run 5 times with a 1 second delay
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT \
-		--sync-after-first-event ${file_sync_after_first} >/dev/null 2>&1
+		     --sync-after-first-event ${file_sync_after_first} >/dev/null 2>&1
+	tracee_pids+=("${!}")
 
 	while [ ! -f "${file_sync_after_first}" ]; do
 		sleep 0.5
@@ -72,7 +76,7 @@ function test_ust_after_start ()
 	destroy_lttng_session_ok $SESSION_NAME
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
 	rm -f ${file_sync_after_first}
 }
 
diff --git a/tests/regression/ust/before-after/test_before_after b/tests/regression/ust/before-after/test_before_after
index f7b954779..f81c2b513 100755
--- a/tests/regression/ust/before-after/test_before_after
+++ b/tests/regression/ust/before-after/test_before_after
@@ -33,7 +33,7 @@ function test_before_apps()
 	start_lttng_tracing_ok $SESSION_NAME
 
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT &
-	wait
+	wait "${!}"
 	ok $? "Traced application stopped."
 
 	stop_lttng_tracing_ok $SESSION_NAME
@@ -62,7 +62,7 @@ function test_after_apps()
 
 	touch ${file_sync_before_last}
 
-	wait
+	wait "${!}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
diff --git a/tests/regression/ust/buffers-pid/test_buffers_pid b/tests/regression/ust/buffers-pid/test_buffers_pid
index a18cdbf05..fcc8a871e 100755
--- a/tests/regression/ust/buffers-pid/test_buffers_pid
+++ b/tests/regression/ust/buffers-pid/test_buffers_pid
@@ -38,6 +38,7 @@ function enable_channel_per_pid()
 test_after_multiple_apps() {
 	local out
 	local i
+	local tracee_pids=()
 
 	diag "Start multiple applications AFTER tracing is started"
 
@@ -50,8 +51,9 @@ test_after_multiple_apps() {
 	for i in `seq 1 5`; do
 		$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT >/dev/null 2>&1 &
 		ok $? "Start application $i for tracing"
+		tracee_pids+=("${!}")
 	done
-	wait
+	wait "${tracee_pids[@]}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -64,6 +66,7 @@ test_after_multiple_apps() {
 test_before_multiple_apps() {
 	local out
 	local i
+	local tracee_pids=()
 	local file_sync_after_first=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX")
 	local file_sync_before_last=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX")
 
@@ -74,6 +77,7 @@ test_before_multiple_apps() {
 			--sync-after-first-event ${file_sync_after_first}_${i} \
 			--sync-before-last-event ${file_sync_before_last}_${i} >/dev/null 2>&1 &
 		ok $? "Start application $i for tracing"
+		tracee_pids+=("${!}")
 	done
 
 	# BEFORE application is spawned
@@ -87,7 +91,7 @@ test_before_multiple_apps() {
 	done
 
 	diag "Waiting for applications to end"
-	wait
+	wait "${tracee_pids[@]}"
 	pass "Waiting done"
 
 	stop_lttng_tracing_ok $SESSION_NAME
@@ -125,7 +129,7 @@ test_after_app() {
 
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT &
 	ok $? "Start application to trace"
-	wait
+	wait "${!}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -137,6 +141,7 @@ test_after_app() {
 
 test_before_app() {
 	local out
+	local pid
 	local file_sync_after_first=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_after_first.XXXXXX")
 	local file_sync_before_last=$(mktemp -u -t "tmp.${FUNCNAME[0]}_sync_before_last.XXXXXX")
 
@@ -152,12 +157,13 @@ test_before_app() {
 		--sync-after-first-event ${file_sync_after_first} \
 		--sync-before-last-event ${file_sync_before_last} &
 	ok $? "Start application to trace"
+	pid="${!}"
 
 	start_lttng_tracing_ok $SESSION_NAME
 
 	touch ${file_sync_before_last}
 
-	wait
+	wait "${pid}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -206,7 +212,7 @@ test_multiple_channels() {
 
 	$TESTAPP_BIN -i $NR_ITER -w $NR_USEC_WAIT &
 	ok $? "Start application to trace"
-	wait
+	wait "${!}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	trace_match_only $EVENT_NAME $[NR_ITER * 5] $TRACE_PATH
diff --git a/tests/regression/ust/high-throughput/test_high_throughput b/tests/regression/ust/high-throughput/test_high_throughput
index 750445a48..7ddfc416c 100755
--- a/tests/regression/ust/high-throughput/test_high_throughput
+++ b/tests/regression/ust/high-throughput/test_high_throughput
@@ -37,12 +37,14 @@ create_lttng_session_ok $SESSION_NAME $TRACE_PATH
 enable_ust_lttng_event_ok $SESSION_NAME $EVENT_NAME
 start_lttng_tracing_ok $SESSION_NAME
 
+pids=()
 for i in `seq 1 $NR_APP`; do
 	./$CURDIR/$BIN_NAME >/dev/null 2>&1 &
+	pids+=("${!}")
 done
 
 diag "Waiting for applications to end"
-wait
+wait "${pids[@]}"
 pass "Wait for applications to end"
 
 stop_lttng_tracing_ok $SESSION_NAME
diff --git a/tests/regression/ust/java-jul/test_java_jul b/tests/regression/ust/java-jul/test_java_jul
index 41e2656ff..a4bc85206 100755
--- a/tests/regression/ust/java-jul/test_java_jul
+++ b/tests/regression/ust/java-jul/test_java_jul
@@ -34,6 +34,7 @@ function run_app
 function run_app_background
 {
 	run_app $@ &
+	tracee_pids+=("${!}")
 }
 
 function enable_jul_loglevel_only()
@@ -94,7 +95,8 @@ function test_jul_before_start ()
 	touch ${file_sync_before_last}
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -511,7 +513,7 @@ function test_jul_destroy_session()
 	run_app_background 0 1
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -530,7 +532,7 @@ function test_jul_destroy_session()
 	run_app_background 0 1
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -670,6 +672,7 @@ else
 	withapp=1
 fi
 
+tracee_pids=()
 skip $withapp "JUL support is needed. Skipping all tests." $NUM_TESTS ||
 {
 	start_lttng_sessiond
diff --git a/tests/regression/ust/java-log4j/test_java_log4j b/tests/regression/ust/java-log4j/test_java_log4j
index fc857b1bd..b2e55c434 100755
--- a/tests/regression/ust/java-log4j/test_java_log4j
+++ b/tests/regression/ust/java-log4j/test_java_log4j
@@ -47,6 +47,7 @@ function run_app
 function run_app_background
 {
 	run_app "${@}" &
+	tracee_pids+=("${!}")
 }
 
 
@@ -72,7 +73,8 @@ function test_log4j_before_start ()
 	touch "${file_sync_before_last}"
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -421,7 +423,8 @@ function test_log4j_destroy_session()
 	# Run 5 times with a 1 second delay
 	run_app_background 0 1
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -436,7 +439,8 @@ function test_log4j_destroy_session()
 	# Run 5 times with a 1 second delay
 	run_app_background 0 1
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -577,6 +581,7 @@ tests=(
 	test_log4j_filter_loglevel
 )
 
+tracee_pids=()
 for fct_test in "${tests[@]}";
 do
 	TRACE_PATH=$(mktemp -d -t tmp.test_java_log4j_trace_path.XXXXXX)
diff --git a/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j b/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j
index 862e4be98..0d8b392b4 100755
--- a/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j
+++ b/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j
@@ -48,6 +48,7 @@ function run_app
 function run_app_background
 {
 	run_app "${@}" &
+	tracee_pids+=("${!}")
 }
 
 
@@ -73,7 +74,8 @@ function test_log4j2_before_start ()
 	touch "${file_sync_before_last}"
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok "log4j2_before_start"
 	destroy_lttng_session_ok "log4j2_before_start"
@@ -422,7 +424,8 @@ function test_log4j2_destroy_session()
 	# Run 5 times with a 1ms delay
 	run_app_background 0 1
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok "log4j2_destroy_session"
 	destroy_lttng_session_ok "log4j2_destroy_session"
@@ -437,7 +440,8 @@ function test_log4j2_destroy_session()
 	# Run 5 times with a 1ms delay
 	run_app_background 0 1
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok "log4j2_destroy_session"
 	destroy_lttng_session_ok "log4j2_destroy_session"
@@ -578,6 +582,7 @@ tests=(
 	test_log4j2_filter_loglevel
 )
 
+tracee_pids=()
 for fct_test in "${tests[@]}";
 do
 	TRACE_PATH=$(mktemp -d -t tmp.test_java_log4j2_trace_path.XXXXXX)
diff --git a/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j2 b/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j2
index c9b12d137..1e3fa44e2 100755
--- a/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j2
+++ b/tests/regression/ust/java-log4j2/test_agent_log4j2_domain_log4j2
@@ -51,6 +51,7 @@ function run_app
 function run_app_background
 {
 	run_app "${@}" &
+	tracee_pids+=("${!}")
 }
 
 
@@ -76,7 +77,8 @@ function test_log4j2_before_start ()
 	touch "${file_sync_before_last}"
 
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok "log4j2_before_start"
 	destroy_lttng_session_ok "log4j2_before_start"
@@ -425,7 +427,8 @@ function test_log4j2_destroy_session()
 	# Run 5 times with a 1ms delay
 	run_app_background 0 1
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok "log4j2_destroy_session"
 	destroy_lttng_session_ok "log4j2_destroy_session"
@@ -440,7 +443,8 @@ function test_log4j2_destroy_session()
 	# Run 5 times with a 1ms delay
 	run_app_background 0 1
 	# Wait for the applications started in background
-	wait
+	wait "${tracee_pids[@]}"
+	tracee_pids=()
 
 	stop_lttng_tracing_ok "log4j2_destroy_session"
 	destroy_lttng_session_ok "log4j2_destroy_session"
@@ -581,6 +585,7 @@ tests=(
 	test_log4j2_filter_loglevel
 )
 
+tracee_pids=()
 for fct_test in "${tests[@]}";
 do
 	TRACE_PATH=$(mktemp --tmpdir -d tmp.test_java_log4j2_trace_path.XXXXXX)
diff --git a/tests/regression/ust/multi-session/test_multi_session b/tests/regression/ust/multi-session/test_multi_session
index e407859c4..7571e43bb 100755
--- a/tests/regression/ust/multi-session/test_multi_session
+++ b/tests/regression/ust/multi-session/test_multi_session
@@ -34,8 +34,7 @@ test_multi_session() {
 
 	"./$CURDIR/gen-nevents" $NR_ITER &
 	ok $? "Start application to generate $NR_ITER events"
-
-	wait
+	wait "${!}"
 	pass "Wait for events to record"
 
 	for i in $(seq 0 3); do
diff --git a/tests/regression/ust/python-logging/test_python_logging.in b/tests/regression/ust/python-logging/test_python_logging.in
index dc7cfaba6..c5ac818d0 100755
--- a/tests/regression/ust/python-logging/test_python_logging.in
+++ b/tests/regression/ust/python-logging/test_python_logging.in
@@ -61,6 +61,7 @@ function run_app
 function run_app_background
 {
 	run_app "$@" &
+	tracee_pids+=("${!}")
 }
 
 function enable_python_loglevel_only()
@@ -129,7 +130,7 @@ function test_python_before_start ()
 
 	# Wait for the applications started in background
 	echo "1" > ${go_file}
-	wait
+	wait "${tracee_pids[@]}"
 
 	stop_lttng_tracing_ok $SESSION_NAME
 	destroy_lttng_session_ok $SESSION_NAME
@@ -762,6 +763,7 @@ else
 	skip_agent=1
 fi
 
+tracee_pids=()
 skip $skip_agent "Python agent test skipped." $NUM_TESTS ||
 {
 	start_lttng_sessiond