@Override
                public void run() {
                    String res = null;
                    try {
                        for (int i = 0; i < invokeTimes; i++) {
                            res = (String) client.invokeSync(addr, req, 3000);
                        }
                    } catch (RemotingException e) {
                        if (e.getMessage().contains("overflow")) {
                            logger.error("overflow exception!");
                            overFlow.add(true);
                        }
                    } catch (InterruptedException e) {
                        String errMsg = "InterruptedException caught in sync!";
                        logger.error(errMsg, e);
                        Assert.fail(errMsg);
                    }
                    logger.warn("Result received in sync: " + res);
                    Assert.assertEquals(RequestBody.DEFAULT_SERVER_RETURN_STR, res);
                }
water mark exception test, set a small buffer mark by system property, and trigger write over flow.

@author xiaomin.cxm
@version $Id: WaterMark_SystemProperty_ExceptionTest.java, v 0.1 Apr 6, 2016 8:58:36 PM xiaomin.cxm Exp $
src/test/java/com/alipay/remoting/rpc/watermark/WaterMark_SystemProperty_ExceptionTest.java