make test: improve stability

Disable automatic garbage collection and run it manually before
running each test case to minimize stalls. Improve vpp subprocess
cleanup. Reduce helper thread count to one and properly clean that
thread once it's not needed.

Change-Id: I3ea78ed9628552b5ef3ff29cc7bcf2d3fc42f2c3
Signed-off-by: Klement Sekera <ksekera@cisco.com>

test/Makefile

@@ -5,8 +5,14 @@ ifndef VPP_PYTHON_PREFIX
 	$(error VPP_PYTHON_PREFIX is not set)
 endif
 
+UNITTEST_EXTRA_OPTS=""
+
+ifeq ($(FAILFAST),1)
+UNITTEST_EXTRA_OPTS="-f"
+endif
+
 PYTHON_VENV_PATH=$(VPP_PYTHON_PREFIX)/virtualenv
-PYTHON_DEPENDS=scapy==2.3.3 pexpect
+PYTHON_DEPENDS=scapy==2.3.3 pexpect subprocess32
 SCAPY_SOURCE=$(PYTHON_VENV_PATH)/lib/python2.7/site-packages/
 BUILD_COV_DIR = $(BR)/test-cov
 
@@ -35,7 +41,7 @@ $(PAPI_INSTALL_DONE): $(PIP_PATCH_DONE)
 	@touch $@
 
 define retest-func
-	@bash -c "source $(PYTHON_VENV_PATH)/bin/activate && python run_tests.py discover -p test_\"*.py\""
+	@bash -c "source $(PYTHON_VENV_PATH)/bin/activate && python run_tests.py discover $(UNITTEST_EXTRA_OPTS) -p test_\"*.py\""
 endef
 
 test: reset verify-python-path $(PAPI_INSTALL_DONE)
@@ -103,6 +109,7 @@ help:
 	@echo ""
 	@echo "Arguments controlling test runs:"
 	@echo " V=[0|1|2]            - set test verbosity level"
+	@echo " FAILFAST=[0|1]       - fail fast if 1, complete all tests if 0"
 	@echo " DEBUG=<type>         - set VPP debugging kind"
 	@echo "    DEBUG=core        - detect coredump and load it in gdb on crash"
 	@echo "    DEBUG=gdb         - allow easy debugging by printing VPP PID "