diff --git a/.github/WORKFLOW-PARAMETERS.md b/.github/WORKFLOW-PARAMETERS.md
new file mode 100644
index 00000000000..151a3eb9332
--- /dev/null
+++ b/.github/WORKFLOW-PARAMETERS.md
@@ -0,0 +1,14 @@
+# Workflow Parameters
+Adding parameters in the Git commit log can control the workflow.
+
+## --filter
+This parameter specifies which workflows to run, instead of running all of them.
+The command format is: `--filter=[flow1][flow2][flow...]` ,
+and it supports setting multiple workflows, with names matching the filename of the yml file.
+
+## --valgrind
+Setting this parameter will cause the test program to be run with `valgrind`.
+
+```shell
+git commit -m "commit message --filter=[core][unit] --valgrind"
+```
diff --git a/core-tests/run.sh b/core-tests/run.sh
index 7a90563a303..ec04e22dfac 100755
--- a/core-tests/run.sh
+++ b/core-tests/run.sh
@@ -7,7 +7,8 @@ tasks=$(./bin/core_tests --gtest_list_tests | awk '/\./')
 for task in $tasks; do
 
     if [ "${SWOOLE_VALGRIND}" = 1 ]; then
-        execute_command="valgrind --leak-check=full --show-leak-kinds=all --track-origins=yes ./bin/core_tests"
+        # --leak-check=full --show-leak-kinds=all --track-origins=yes
+        execute_command="valgrind ./bin/core_tests"
     else
         execute_command="./bin/core_tests"
     fi
diff --git a/core-tests/src/core/string.cpp b/core-tests/src/core/string.cpp
index 7b2a1a2040c..6e285616e34 100644
--- a/core-tests/src/core/string.cpp
+++ b/core-tests/src/core/string.cpp
@@ -262,10 +262,10 @@ TEST(string, ends_with) {
 
 TEST(string, append_number) {
     string data = "hello";
-    auto str = swoole::make_string(data.length());
+    auto str = swoole::make_string(data.length() + 32);
     str->append(data.c_str(), data.length());
     str->append(123);
-    str->str[str->length] = '\0';
+    str->set_null_terminated();
     EXPECT_STREQ(str->str, data.append("123").c_str());
 
     str->print(true);
diff --git a/include/swoole_string.h b/include/swoole_string.h
index e89f0e9ecab..45b5e6916c9 100644
--- a/include/swoole_string.h
+++ b/include/swoole_string.h
@@ -246,6 +246,13 @@ class String {
         }
     }
 
+    void set_null_terminated() {
+        if (length == size) {
+            extend(length + 1);
+        }
+        str[length] = '\0';
+    }
+
     int append(int value);
 
     ssize_t split(const char *delimiter, size_t delimiter_length, const StringExplodeHandler &handler);