[fix](cgroup) Fix cgroup compatibility with MacOS

be/src/util/cgroup_util.cpp

@@ -193,6 +193,7 @@ std::string CGroupUtil::cgroupv2_of_process() {
 }
 
 std::optional<std::string> CGroupUtil::get_cgroupsv2_path(const std::string& subsystem) {
+#if defined(OS_LINUX)
     if (!CGroupUtil::cgroupsv2_enable()) {
         return {};
     }
@@ -209,6 +210,9 @@ std::optional<std::string> CGroupUtil::get_cgroupsv2_path(const std::string& sub
         current_cgroup = current_cgroup.parent_path();
     }
     return {};
+#else
+    return {};
+#endif
 }
 
 Status CGroupUtil::read_int_line_from_cgroup_file(const std::filesystem::path& file_path,

be/src/util/cgroup_util.h

@@ -26,11 +26,9 @@
 #include "common/status.h"
 namespace doris {
 
-#if defined(OS_LINUX)
 // I think it is possible to mount the cgroups hierarchy somewhere else (e.g. when in containers).
 // /sys/fs/cgroup was still symlinked to the actual mount in the cases that I have seen.
 static inline const std::filesystem::path default_cgroups_mount = "/sys/fs/cgroup";
-#endif
 
 /* Cgroup debugging steps
  * CgroupV1:
@@ -52,7 +50,12 @@ class CGroupUtil {
 public:
     enum class CgroupsVersion : uint8_t { V1, V2 };
 
-    // detect if cgroup is enabled
+    // Detect if cgroup is enabled.
+    // If true, it only means that the OS allows the use of Cgroup v1 or v2,
+    // not that the current BE process is using Cgroup.
+    // To confirm whether the process is using Cgroup need to use `find_global_cgroupv1` or `cgroupv2_of_process`.
+    // To confirm whether the process is using a subsystem of Cgroup,
+    // need to use `find_abs_cgroupv1_path` or `get_cgroupsv2_path`.
     static bool cgroupsv1_enable();
     static bool cgroupsv2_enable();