src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemFactory.java

@  rev 57446 : Review changes
|
o  rev 57445 : 8231111: Cgroups v2: Rework Metrics in java.base so as to recognize unified hierarchy
|  Reviewed-by: bobv
~
o  rev 56863 : 8231111: Cgroups v2: Rework Metrics in java.base so as to recognize unified hierarchy
|  Reviewed-by: bobv
~

*** 64,85 ****
              }
          } catch (IOException e) {
              return null;
          }
  
!         // For cgroups v1 all controllers need to have non-null hierarchy id
          boolean isCgroupsV2 = true;
          boolean anyControllersEnabled = false;
          for (CgroupInfo info: infos.values()) {
              isCgroupsV2 = isCgroupsV2 && info.getHierarchyId() == 0;
              anyControllersEnabled = anyControllersEnabled || info.isEnabled();
          }
  
          // If no controller is enabled, return no metrics.
          if (!anyControllersEnabled) {
              return null;
          }
  
          if (isCgroupsV2) {
              // read mountinfo so as to determine root mount path
              String mountPath = null;
              try (Stream<String> lines =
--- 64,96 ----
              }
          } catch (IOException e) {
              return null;
          }
  
!         // For cgroups v1 all controllers need to have non-zero hierarchy id
          boolean isCgroupsV2 = true;
          boolean anyControllersEnabled = false;
+         boolean anyCgroupsV2Controller = false;
+         boolean anyCgroupsV1Controller = false;
          for (CgroupInfo info: infos.values()) {
+             anyCgroupsV1Controller = anyCgroupsV1Controller || info.getHierarchyId() != 0;
+             anyCgroupsV2Controller = anyCgroupsV2Controller || info.getHierarchyId() == 0;
              isCgroupsV2 = isCgroupsV2 && info.getHierarchyId() == 0;
              anyControllersEnabled = anyControllersEnabled || info.isEnabled();
          }
  
          // If no controller is enabled, return no metrics.
          if (!anyControllersEnabled) {
              return null;
          }
+         // Warn about mixed cgroups v1 and cgroups v2 controllers. The code is
+         // not ready to deal with that on a per-controller basis. Return no metrics
+         // in that case
+         if (anyCgroupsV1Controller && anyCgroupsV2Controller) {
+             System.err.println("Warning: Mixed cgroupv1 and cgroupv2 not supported. Metrics disabled.");
+             return null;
+         }
  
          if (isCgroupsV2) {
              // read mountinfo so as to determine root mount path
              String mountPath = null;
              try (Stream<String> lines =