Add the ability to set the number of parallel tests from cmake and have sanitizer tests do so

With the forthcoming new sanitizer image running tests in parallel
causes machines to run out of resources, and fail tests spuriously
This commit forces test_sanitizers.sh to run tests sequentially to
prevent this.

scripts/test_sanitizers.sh

@@ -93,7 +93,7 @@ docker exec -u postgres \
     -e CMAKE_BUILD_TYPE="Debug" \
     -e PG_SOURCE_DIR="/usr/src/postgresql/" \
     timescaledb-san /bin/bash -c \
-    "cd /tsdb_build/timescaledb && BUILD_FORCE_REMOVE=true ./bootstrap && cd build && make"
+    "cd /tsdb_build/timescaledb && BUILD_FORCE_REMOVE=true ./bootstrap -DTEST_GROUP_SIZE=1 && cd build && make"
 
 wait_for_pg timescaledb-san
 

test/sql/CMakeLists.txt

@@ -160,7 +160,14 @@ endforeach(TEMPLATE_FILE)
 
 list(SORT TEST_FILES)
 file(REMOVE ${TEST_SCHEDULE})
-set(PARALLEL_GROUP_SIZE 20)
+
+if(NOT TEST_GROUP_SIZE)
+  set(PARALLEL_GROUP_SIZE 20)
+else()
+  set(PARALLEL_GROUP_SIZE ${TEST_GROUP_SIZE})
+endif()
+
+message("PGC ${PARALLEL_GROUP_SIZE} ${TEST_GROUP_SIZE}")
 
 # append solo tests to schedule first
 foreach(TEST_FILE ${TEST_FILES})
@@ -183,11 +190,16 @@ foreach(TEST_FILE ${TEST_FILES})
 endforeach(TEST_FILE)
 file(APPEND ${TEST_SCHEDULE} "\n")
 
-file(APPEND ${TEST_SCHEDULE} "test: ")
+
+set(GROUP_MEMBERS 0)
 foreach(TEST_FILE ${TEST_FILES})
   string(REGEX REPLACE "(.+)\.sql" "\\1" TESTS_TO_RUN ${TEST_FILE})
   if(TESTS_TO_RUN IN_LIST POST_TESTS)
+    if(GROUP_MEMBERS EQUAL 0)
+      file(APPEND ${TEST_SCHEDULE} "\ntest: ")
+    endif()
     file(APPEND ${TEST_SCHEDULE} "${TESTS_TO_RUN} ")
+    MATH(EXPR GROUP_MEMBERS "(${GROUP_MEMBERS}+1)%${PARALLEL_GROUP_SIZE}")
   endif()
 endforeach(TEST_FILE)
 file(APPEND ${TEST_SCHEDULE} "\n")