#vulnerable code 
                                public AvProxy bind(String url, Object userID) {
        if (testUrls.size() < 10) {
            testUrls.add(url);
        } else {
            testUrls.set(random.nextInt(10), url);
        }
        if (consistentBuckets.size() < minSize) {
            fresh();
        }

        readWriteLock.readLock().lock();
        try {// 注意hash空间问题,之前是Integer,hash值就是字面值,导致hash空间只存在了正数空间
            AvProxy hint = hint(userID == null ? String.valueOf(random.nextInt()).hashCode() : userID.hashCode());
            if (userID != null && hint != null) {
                if (!hint.equals(bindMap.get(userID))) {
                    // IP 绑定改变事件
                }
                bindMap.put(userID, hint);
            }
            return hint;
        } finally {
            readWriteLock.readLock().unlock();
        }
    } 
                            #location 8 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                public AvProxy bind(String url, Object userID) {
        if (testUrls.size() < 10) {
            testUrls.add(url);
        } else {
            testUrls.set(random.nextInt(10), url);
        }
        if (consistentBuckets.size() < minSize) {
            refreshInNewThread();//在新线程刷新
        }

        readWriteLock.readLock().lock();
        try {
            if(consistentBuckets.size() ==0){
                return Context.getInstance().getDefaultProxy();
            }
            // 注意hash空间问题,之前是Integer,hash值就是字面值,导致hash空间只存在了正数空间
            AvProxy hint = hint(userID == null ? String.valueOf(random.nextInt()).hashCode() : userID.hashCode());
            if (userID != null && hint != null) {
                if (!hint.equals(bindMap.get(userID))) {
                    // IP 绑定改变事件
                }
                bindMap.put(userID, hint);
            }
            return hint;
        } finally {
            readWriteLock.readLock().unlock();
        }
    }