＆＃34;暂时失败＆＃34;在Azure缓存服务上

Question

从昨晚凌晨2点左右开始 - 大约8小时后，任何人触及与网站有关的任何事情 - 我们的Azure网站开始抛出此错误：

错误：ErrorCode：SubStatus：暂时失败。请稍后重试。 （一个或多个指定的缓存服务器不可用，这可能是由繁忙的网络或服务器引起的。对于内部部署缓存集群，还要验证以下条件。确保已为此客户端帐户授予安全权限，并检查AppFabric允许缓存服务通过所有缓存主机上的防火墙。服务器上的MaxBufferSize也必须大于或等于从客户端发送的序列化对象大小。）。附加信息：客户端尝试与服务器通信：net.tcp：//payboardprod.cache.windows.net：22233。 （在Microsoft.ApplicationServer.Caching.DataCache.ThrowException（ErrStatus errStatus，Guid trackingId，Exception responseException，Byte [] [] payload，EndpointID destination）

基本上，我们的Azure缓存服务器看起来好像很有用。但是我们的Azure管理控制台上没有任何迹象表明这一点，这表明有问题的缓存服务器运行正常。 Azure服务可用性仪表板（http://azure.microsoft.com/en-us/support/service-dashboard/）上也没有任何问题迹象。任何类型问题的唯一指示是我们的Azure缓存服务在凌晨1点左右开始报告零请求。

我们的测试版网站使用了不同的缓存服务器，但配置相同，在整个剧集中保持不变。

我们只有一个BizSpark帐户，因此无法使用MS打开支持服务单。

我们通过禁用外部缓存来恢复服务，但这显然不是最佳的。

有关此问题的任何建议？

Answer 1

将您的呼叫代码包裹在适当的保护（try / catch）中，然后应对应用层的失败。任何云中提供的商品平台都可以（并且确实）不时出现这些问题。您需要进行日志记录并在Azure Diagnostics（http://msdn.microsoft.com/en-us/library/gg433048.aspx）之类的某个位置进行日志记录，以便以后进行故障排除。

Answer 2

我仍然无法弄清楚问题是什么，并且最终关注了西蒙W关于将所有内容包装在试图/抓住wazoo中的建议。但是因为它不是100％直观的，并且我花了好几次尝试来获取正确的缓存检索代码，我想我会在这里发布它给任何感兴趣的人。

public TValue Get(string key, Func<TValue> missingFunc)
{
    // We need to ensure that two processes don't try to calculate the same value at the same time. That just wastes resources.
    // So we pull out a value from the _cacheLocks dictionary, and lock on that before trying to retrieve the object.
    // This does add a bit more locking, and hence the chance for one process to lock up everything else.
    // We may need to add some timeouts here at some point in time. It also doesn't prevent two processes on different
    // machines from trying the same bit o' nonsense. Oh well. It's probably still a worthwhile optimization.
    key = _keyPrefix + "." + key;
    var value = default(TValue);
    object cacheLock;
    lock (_cacheLocks)
    {
        if (!_cacheLocks.TryGetValue(key, out cacheLock))
        {
            cacheLock = new object();
            _cacheLocks[key] = cacheLock;
        }
    }
    lock (cacheLock)
    {
        // Try to get the value from the cache.
        try
        {
            value = _cache.Get(key) as TValue;
        }
        catch (SerializationException ex)
        {
            // This can happen when the app restarts, and we discover that the dynamic entity names have changed, and the desired type 
            // is no longer around, e.g., "Organization_6BA9E1E1184D9B7BDCC50D94471D7A730423456A15BBAFB6A2C6AC0FF94C0D41"
            // If that's the error, we should probably warn about it, but no point in logging it as an error, since it's more-or-less expected.
            _logger.Warn("Error retrieving item '" + key + "' from Azure cache; falling back to missingFunc(). Error = " + ex);
        }
        catch (Exception ex)
        {
            _logger.Error("Error retrieving item '" + key + "' from Azure cache; falling back to missingFunc(). Error = " + ex);
        }

        // If we didn't get anything interesting, then call the function that should be able to retrieve it for us.
        if (value == default(TValue))
        {
            // If that function throws an exception, don't swallow it.
            value = missingFunc();

            // If we try to put it into the cache, and *that* throws an exception, 
            // log it, and then swallow it.
            try
            {
                _cache.Put(key, value);
            }
            catch (Exception ex)
            {
                _logger.Error("Error putting item '" + key + "' into Azure cache. Error = " + ex);
            }
        }
    }
    return value;
}

您可以像这样使用它：

var user = UserCache.Get(email, () =>
    _db.Users
        .FirstOrDefault(u => u.Email == email)
        .ShallowClone());