Created attachment 38104 [details]
the line 1476 encounter a exception

tomcat-embed-core-8.5.23.jar

if org.apache.tomcat.util.net.NioEndpoint.SocketProcessor#doRun  encounter exception before connection closed and it is not CancelledKeyException class,it will trigger throw exception to the third catch code block. 


if org.apache.tomcat.util.net.NioEndpoint.SocketProcessor#doRun (line 1453 -- line 1485)

                if (handshake == 0) {
                    SocketState state = SocketState.OPEN;
                    // Process the request from this socket
                    if (event == null) {
                        state = getHandler().process(socketWrapper, SocketEvent.OPEN_READ);
                    } else {
                        state = getHandler().process(socketWrapper, event);
                    }
                    if (state == SocketState.CLOSED) {
                        close(socket, key);
                    }
                } else if (handshake == -1 ) {
                    close(socket, key);
                } else if (handshake == SelectionKey.OP_READ){
                    socketWrapper.registerReadInterest();
                } else if (handshake == SelectionKey.OP_WRITE){
                    socketWrapper.registerWriteInterest();
                }
            } catch (CancelledKeyException cx) {
                socket.getPoller().cancelledKey(key);
            } catch (VirtualMachineError vme) {
                ExceptionUtils.handleThrowable(vme);
            } catch (Throwable t) {
                log.error("", t);
                socket.getPoller().cancelledKey(key);
            } finally {
                socketWrapper = null;
                event = null;
                //return to cache
                if (running && !paused) {
                    processorCache.push(this);
                }
            }


and in the catch block  if the first line code(line 1476) encounter exception, the second line code(line 1477) will be skip. and the socket will be not closed, ,and make a socket connection  leak.