解决仅通过索引视图相关的 2 个表的死锁

Question

我遇到了陷入僵局的情况，我想我已经缩小了罪魁祸首的范围，但我不太确定我能做些什么来解决它。

这是在运行 SQL Server 2008 R2 的生产环境中进行的。

为了让您稍微简化一下情况：

---

我有 3 个表，定义如下：

TABLE activity (
    id, -- PK
    ...
)

TABLE member_activity (
    member_id, -- PK col 1
    activity_id, -- PK col 2
    ...
)

TABLE follow (
    id, -- PK
    follower_id,
    member_id,
    ...
)

该member_activity表有一个定义为 的复合主键member_id, activity_id，因为我只需要以这种方式查找该表上的数据。

我也有一个非聚集索引follow：

CREATE NONCLUSTERED INDEX [IX_follow_member_id_includes] 
ON follow ( member_id ASC ) INCLUDE ( follower_id )

此外，我有一个 Schema-bound 视图network_activity，其定义如下：

CREATE VIEW network_activity
WITH SCHEMABINDING
AS

SELECT
    follow.follower_id as member_id,
    member_activity.activity_id as activity_id,
    COUNT_BIG(*) AS cb
FROM member_activity
INNER JOIN follow ON follow.member_id = member_activity.member_id
INNER JOIN activity ON activity.id = member_activity.activity_id
GROUP BY follow.follower_id, member_activity.activity_id

其中还有一个唯一的聚集索引：

CREATE UNIQUE CLUSTERED INDEX [IX_network_activity_unique_member_id_activity_id] 
ON network_activity
(
    member_id ASC,
    activity_id ASC
)

---

现在，我有两个死锁的存储过程。他们经历以下过程：

-- SP1: insert activity
-----------------------
INSERT INTO activity (...)
SELECT ... FROM member_activity WHERE member_id = @a AND activity_id = @b
INSERT INTO member_activity (...)


-- SP2: insert follow
---------------------
SELECT follow WHERE member_id = @x AND follower_id = @y
INSERT INTO follow (...)

这两个过程都在 READ COMMITTED 隔离中运行。我设法查询了 1222 个扩展事件输出，并就死锁解释了以下内容：

SP1 正在等待索引RangeS-S上的键锁，IX_follow_member_id_includes而 SP2 持有冲突 (X) 锁

SP2 正在等待S模式锁定，PK_member_activity 而 SP1 持有冲突 (X) 锁定

死锁似乎发生在每个查询的最后一行（插入）。我不清楚的是为什么 SP1 想要锁定IX_follow-member_id_includes索引。对我来说，唯一的链接似乎来自这个索引视图，这就是我将它包含在内的原因。

对我来说，防止这些僵局发生的最佳方法是什么？任何帮助将非常感激。我在解决死锁问题方面没有太多经验。

请让我知道是否有我可以提供的更多信息可能会有所帮助！

提前致谢。

---

编辑 1：为每个请求添加更多信息。

这是此死锁的 1222 输出：

<deadlock>
    <victim-list>
        <victimProcess id="process4c6672748" />
    </victim-list>
    <process-list>
        <process id="process4c6672748" taskpriority="0" logused="332" waitresource="KEY: 8:72057594104905728 (25014f77eaba)" waittime="581" ownerId="474698706" transactionname="INSERT" lasttranstarted="2014-07-03T17:03:12.287" XDES="0x298487970" lockMode="RangeS-S" schedulerid="1" kpid="972" status="suspended" spid="79" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2014-07-03T17:03:12.283" lastbatchcompleted="2014-07-03T17:03:12.283" lastattention="2014-07-03T10:25:00.283" clientapp=".Net SqlClient Data Provider" hostname="WIN08CLYDESDALE" hostpid="4596" loginname="TechPro" isolationlevel="read committed (2)" xactid="474698706" currentdb="8" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
            <executionStack>
                <frame procname="" line="7" stmtstart="1194" stmtend="1434" sqlhandle="0x02000000a26bb72a2b220406876cad09c22242e5265c82e6" />
                <frame procname="" line="1" sqlhandle="0x000000000000000000000000000000000000000000000000" />
            </executionStack>
            <inputbuf> <!-- SP 1 --> </inputbuf>
        </process>
        <process id="process6cddc5b88" taskpriority="0" logused="456" waitresource="KEY: 8:72057594098679808 (89013169fc76)" waittime="567" ownerId="474698698" transactionname="INSERT" lasttranstarted="2014-07-03T17:03:12.283" XDES="0x30c459970" lockMode="S" schedulerid="4" kpid="4204" status="suspended" spid="70" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2014-07-03T17:03:12.283" lastbatchcompleted="2014-07-03T17:03:12.283" lastattention="2014-07-03T15:04:55.870" clientapp=".Net SqlClient Data Provider" hostname="WIN08CLYDESDALE" hostpid="4596" loginname="TechPro" isolationlevel="read committed (2)" xactid="474698698" currentdb="8" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056">
            <executionStack>
                <frame procname="" line="18" stmtstart="942" stmtend="1250" sqlhandle="0x03000800ca458d315ee9130100a300000100000000000000" />
            </executionStack>
            <inputbuf> <!-- SP 2 --> </inputbuf>
        </process>
    </process-list>
    <resource-list>
        <keylock hobtid="72057594104905728" dbid="8" objectname="" indexname="" id="lock33299fc00" mode="X" associatedObjectId="72057594104905728">
            <owner-list>
                <owner id="process6cddc5b88" mode="X" />
            </owner-list>
            <waiter-list>
                <waiter id="process4c6672748" mode="RangeS-S" requestType="wait" />
            </waiter-list>
        </keylock>
        <keylock hobtid="72057594098679808" dbid="8" objectname="" indexname="" id="lockb7e2ba80" mode="X" associatedObjectId="72057594098679808">
            <owner-list>
                <owner id="process4c6672748" mode="X" />
            </owner-list>
            <waiter-list>
                <waiter id="process6cddc5b88" mode="S" requestType="wait" />
            </waiter-list>
        </keylock>
    </resource-list>
</deadlock>

在这种情况下，

AssociatedObjectId 72057594098679808 对应 member_activity, PK_member_activity

AssociatedObjectId 72057594104905728 对应 follow, IX_follow_member_id_includes

此外，这里有一张更精确的图片，说明 SP1 和 SP2 正在做什么

-- SP1: insert activity
-----------------------
DECLARE @activityId INT

INSERT INTO activity (field1, field2)
VALUES (@field1, @field2)

SET @activityId = SCOPE_IDENTITY();

IF NOT EXISTS(
    SELECT TOP 1 member_id 
    FROM member_activity 
    WHERE member_id = @m1 AND activity_id = @activityId
)
    INSERT INTO member_activity (member_id, activity_id, field1)
    VALUES (@m1, @activityId, @field1)

IF NOT EXISTS(
    SELECT TOP 1 member_id 
    FROM member_activity 
    WHERE member_id = @m2 AND activity_id = @activityId
)
    INSERT INTO member_activity (member_id, activity_id, field1)
    VALUES (@m2, @activityId, @field1)

还有 SP2：

-- SP2: insert follow
---------------------

IF NOT EXISTS(
    SELECT TOP 1 1 
    FROM follow
    WHERE member_id = @memberId AND follower_id = @followerId
)
    INSERT INTO follow (member_id, follower_id)
    VALUES (@memberId, @followerId)

---

编辑 2：重读评论后，我想我还要添加一些关于哪些列是外键的信息......

• member_activity.member_id是member表的外键
• member_activity.activity_id是activity表的外键
• follow.member_id是member表的外键
• follow.follower_id是member表的外键

---

更新 1：

我做了一些我认为可能有助于防止僵局的更改，但没有运气。

我所做的更改如下：

-- SP1: insert activity
-----------------------
DECLARE @activityId INT

INSERT INTO activity (field1, field2)
VALUES (@field1, @field2)

SET @activityId = SCOPE_IDENTITY();

MERGE member_activity WITH ( HOLDLOCK ) as target
USING (SELECT @m1 as member_id, @activityId as activity_id, @field1 as field1) as source
    ON target.member_id = source.member_id
    AND target.activity_id = source.activity_id
WHEN NOT MATCHED THEN
    INSERT (member_id, activity_id, field1)
    VALUES (source.member_id, source.activity_id, source.field1)
;

MERGE member_activity WITH ( HOLDLOCK ) as target
USING (SELECT @m2 as member_id, @activityId as activity_id, @field1 as field1) as source
    ON target.member_id = source.member_id
    AND target.activity_id = source.activity_id
WHEN NOT MATCHED THEN
    INSERT (member_id, activity_id, field1)
    VALUES (source.member_id, source.activity_id, source.field1)
;

和 SP2：

-- SP2: insert follow
---------------------

SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
BEGIN TRANSACTION

IF NOT EXISTS(
    SELECT TOP 1 1 
    FROM follow WITH ( UPDLOCK )
    WHERE member_id = @memberId AND follower_id = @followerId
)
    INSERT INTO follow (member_id, follower_id)
    VALUES (@memberId, @followerId)

COMMIT

有了这两个变化，我似乎仍然陷入僵局。

如果还有什么我可以提供的，请告诉我。谢谢。

Answer 1

冲突归结为network_activity需要跨 DML 语句（内部）维护的索引视图。这很可能是 SP1 想要锁定IX_follow-member_id_includes索引的原因，因为它可能被视图使用（它看起来是视图的覆盖索引）。

两种可能的选择：

1. 考虑删除视图上的聚集索引，使其不再是索引视图。拥有它的好处是否超过维护成本？您是否足够频繁地从中进行选择，或者将其编入索引所带来的性能提升是否值得？如果您相当频繁地运行这些过程，那么成本可能高于收益？

2. 如果将视图编入索引的好处确实超过了成本，那么请考虑针对该视图的基表隔离 DML 操作。这可以通过使用应用程序锁来完成（请参阅sp_getapplock和sp_releaseapplock）。应用程序锁让您可以围绕任意概念创建锁。意思是，您可以@Resource在两个存储过程中将其定义为“network_activity”，这将迫使它们等待轮到它们。每个 proc 将遵循相同的结构：

   BEGIN TRANSACTION;
   EXEC sp_getapplock @Resource = 'network_activity', @LockMode = 'Exclusive';
   ...current proc code...
   EXEC sp_releaseapplock @Resource = 'network_activity';
   COMMIT TRANSACTION;
   

   您需要自己管理错误ROLLBACK（如链接的 MSDN 文档中所述），因此请放入通常的TRY...CATCH. 但是，这确实可以让您管理这种情况。
   请注意： sp_getapplock /sp_releaseapplock应谨慎使用；应用程序锁绝对可以非常方便（例如在这种情况下），但只有在绝对必要时才应该使用它们。