sql-server – SQL Server – 两个进程如何专门(X)锁定相同的页面？

如果我正确地解密了以下死锁图,它看起来像两个进程(SPID：216和209)在同一页上拥有独占(X)锁：

XDL<资源列表>节目

<pagelock
    fileid="1"
    pageid="17410848"
    dbid="21"
    subresource="FULL"
    objectname="33bd93e0-f5b2-43f6-93ca-56bbe6493e0c.dbo.sync_publishers2"
    id="lock630b1d5380"
    mode="X"
    associatedobjectId="72057608416264192">
    <owner-list>
        <owner
            id="process90763f08c8"
            mode="X"
            requestType="wait" />
    </owner-list>
    <waiter-list>
        <waiter
            id="process861129bc28"
            mode="X"
            requestType="wait" />
    </waiter-list>
</pagelock>

还有一点点

<pagelock
    fileid="1"
    pageid="17410848"
    dbid="21"
    subresource="FULL"
    objectname="33bd93e0-f5b2-43f6-93ca-56bbe6493e0c.dbo.sync_publishers2"
    id="lock630b1d5380"
    mode="X"
    associatedobjectId="72057608416264192">
    <owner-list>
        <owner
            id="process90763f04e8"
            mode="X" />
    </owner-list>
    <waiter-list>
        <waiter
            id="process90763f08c8"
            mode="X"
            requestType="wait" />
    </waiter-list>
</pagelock>

怎么可能,这是什么意思？

完整的死锁定义如下：http://pastebin.com/A4Te3Chx.

UPD：我已经在Microsoft Connect上提交了一个项目来尝试收集权威回应：https://connect.microsoft.com/SQLServer/Feedback/Details/3119334.

解决方法

这只是意味着有一个等待该锁的队列.

您可以使用以下命令重新生成(运行setup,然后是tran 1.然后,您可以在15秒内按顺序在不同的连接中启动tran 2和tran 3).

建立

USE tempdb

CREATE TABLE T
  (
     X INT PRIMARY KEY WITH(ALLOW_ROW_LOCKS = OFF),Filler AS CAST('A' AS CHAR(8000)) PERSISTED
  );

INSERT INTO T VALUES (1),(2),(3);

特兰1

SET XACT_ABORT ON
USE tempdb -- t1

BEGIN TRAN

UPDATE T   SET X = X WHERE X = 1

WAITFOR DELAY '00:00:15' 


--See what locks are granted just before the deadlock
SELECT resource_description,request_status,request_session_id,X
FROM   sys.dm_tran_locks tl
        LEFT JOIN T WITH(NOLOCK)
            ON sys.fn_PhysLocFormatter(T.%% physloc%%) = '(' + RTRIM(resource_description) + ':0)'
WHERE  resource_associated_entity_id = (SELECT partition_id
                                        FROM   sys.partitions
                                        WHERE  object_id = object_id('T'));

RAISERROR ('',1) WITH NowAIT;

UPDATE T  SET X = X WHERE X = 3

WAITFOR DELAY '00:00:20'
ROLLBACK

特兰2

SET XACT_ABORT ON
USE tempdb -- t2

BEGIN TRAN

UPDATE T SET X = X WHERE X = 2

UPDATE T  SET X = X WHERE X = 1

WAITFOR DELAY '00:00:20'
ROLLBACK

特兰3

SET XACT_ABORT ON

USE tempdb -- t3
BEGIN TRAN

UPDATE T  SET    X = X WHERE  X = 3    

UPDATE T SET    X = X WHERE  X = 1

ROLLBACK

在请求锁定之前立即对tran_locks进行查询的结果将会导致死锁

+----------------------+----------------+--------------------+---+
| resource_description | request_status | request_session_id | X |
+----------------------+----------------+--------------------+---+
| 4:416                | GRANT          |                 61 | 1 |
| 4:416                | WAIT           |                 64 | 1 |
| 4:416                | WAIT           |                 65 | 1 |
| 4:418                | GRANT          |                 64 | 2 |
| 4:419                | GRANT          |                 65 | 3 |
+----------------------+----------------+--------------------+---+

我收到的死锁图如下.

虽然它说死锁的受害者正在等待tran 2拥有的锁,但实际上并不是这样.在僵局的时候,锁由tran 1拥有,而tran 2在第3轮之前首先排在第一位.

死锁图XML显示了这一点,因为它具有相同资源的两个节点(第416页),而“所有者”中有一个requestType =“等待”

<resource-list>
    <pagelock
        fileid="4"
        pageid="416"
        dbid="2"
        subresource="FULL"
        objectname="tempdb.dbo.T"
        id="lock2486d8c4380"
        mode="X"
        associatedobjectId="936748728230805504">
        <owner-list>
            <owner
                id="process2486ba0cca8"
                mode="X"
                requestType="wait" />
        </owner-list>
        <waiter-list>
            <waiter
                id="process2485370c8c8"
                mode="X"
                requestType="wait" />
        </waiter-list>
    </pagelock>
    <pagelock
        fileid="4"
        pageid="416"
        dbid="2"
        subresource="FULL"
        objectname="tempdb.dbo.T"
        id="lock2486d8c4380"
        mode="X"
        associatedobjectId="936748728230805504">
        <owner-list>
            <owner
                id="process2485370c4e8"
                mode="X" />
        </owner-list>
        <waiter-list>
            <waiter
                id="process2486ba0cca8"
                mode="X"
                requestType="wait" />
        </waiter-list>
    </pagelock>
    <pagelock
        fileid="4"
        pageid="419"
        dbid="2"
        subresource="FULL"
        objectname="tempdb.dbo.T"
        id="lock248636ace80"
        mode="X"
        associatedobjectId="936748728230805504">
        <owner-list>
            <owner
                id="process2485370c8c8"
                mode="X" />
        </owner-list>
        <waiter-list>
            <waiter
                id="process2485370c4e8"
                mode="X"
                requestType="wait" />
        </waiter-list>
    </pagelock>
</resource-list>