src/java.base/share/classes/java/net/MulticastSocket.java

M MulticastSocket.java

*** 807,831 ****
                      }
                  } // synch p
              }  //synch ttl
      } //method
  
!     private static Set<SocketOption<?>> options;
!     private static boolean optionsSet = false;
  
      @Override
      public Set<SocketOption<?>> supportedOptions() {
!         synchronized (MulticastSocket.class) {
!             if (optionsSet) {
                  return options;
!             }
              try {
                  DatagramSocketImpl impl = getImpl();
                  options = Collections.unmodifiableSet(impl.supportedOptions());
!             } catch (SocketException ex) {
                  options = Collections.emptySet();
              }
!             optionsSet = true;
!             return options;
          }
      }
  }
--- 807,835 ----
                      }
                  } // synch p
              }  //synch ttl
      } //method
  
!     private volatile Set<SocketOption<?>> options;
!     private final Object optionsLock = new Object();
  
      @Override
      public Set<SocketOption<?>> supportedOptions() {
!         Set<SocketOption<?>> options = this.options;
!          if (options != null)
               return options;
! 
!          synchronized (optionsLock) {
!             options = this.options;
!             if (options != null)
!                 return options;
! 
              try {
                  DatagramSocketImpl impl = getImpl();
                  options = Collections.unmodifiableSet(impl.supportedOptions());
!             } catch (IOException e) {
                  options = Collections.emptySet();
              }
!             return this.options = options;
          }
      }
  }