那些遇到过的问题

具有两个Update SQL语句的同一表上的死锁错误

use*_*948 8 c# sql t-sql deadlock database-deadlocks

我有一个C#项目,它将数据写入TSQL数据库.在循环中运行有两个更新语句,例如:

 for (int i = 0; i < customersProducts.Count; i++) {
     CustomerProducts c = customersProducts[i];

     // Update product dimensions
     for (int j = 0; j < c.Count; j++) {
         Product p = c[j];
         updateProductDimensions(p);
     }

     // ... some processing

     // Update product
     for (int j = 0; j < c.Count; j++) {
         Product p = c[j];
         updateProduct(p);
     }
 }
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在updateProductDimensions()与updateProduct()两个触发SQL Update语句.更新的列中存在一些重叠:

string updateProductDimensions = "UPDATE products SET width = @width, height = @height, length = @length WHERE id = @id";
string updateProduct = "UPDATE products SET width = @width, height = @height, length = @length, customer_id = @customer_id, weight = @weight .... WHERE id = @id";
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示例updateProductDimensions()方法 - updateProduct()也类似:

public void updateProductDimensions(Product p) {
     SqlConnection connection = DBFactory.getConnection();
     string updateProductDimensions = "UPDATE products SET width = @width, height = @height, length = @length WHERE id = @id";

     try
     {
         SqlCommand sqlCmd = new sqlCmd(updateProductDimensions, connection);
         sqlCmd.Parameters.AddWithValue("@width", 20);
         sqlCmd.Parameters.AddWithValue("@height", 10);
         sqlCmd.Parameters.AddWithValue("@length", 30);
         sqlCmd.Parameters.AddWithValue("@id", p.id);
         sqlCmd.CommandType = CommandType.Text;

         sqlCmd.ExecuteNonQuery();

     }
     catch (Exception e)
     {
         // Handle exception
     }
     finally
     {
         connection.Close();
     }
}
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我运行了一个SQL Server死锁跟踪,它显示该updateProduct语句失败(即受害者进程),幸存的进程是运行该updateProductDimensions语句的进程.

死锁跟踪的简化版本如下(最新的进程优先):

 - updateProduct2: fail
 - updateProduct2: success
 - updateProduct1: success
 - updateProductDimensions4: success
 - updateProductDimensions3: success
 - updateProductDimensions2: success
 - updateProductDimensions1: success
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每行代表每次for loop迭代更新一个产品.

以及资源/所有者列表updateProduct2:

  - owner: updateProductDimensions1 (mode = U, isolationLevel = read committed (2))
  - waiter: updateProduct2 (mode= U, requestType = wait, isolationLevel = read committed (2))
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我的问题是,为什么会出现死锁？即使两个语句更新同一行,它也是同一个表.服务器与多个客户端通信,客户端只能更新自己的产品 - 即.单个产品只能由一个特定客户更新.这样,多个数据库更新同时发生,但对于不同的行(产品).

如何在不删除重复的更新列的情况下解决这个问题？

为products表创建语句:

    CREATE TABLE Products (
        [id]               VARCHAR (255)    NOT NULL,
        [width]            INT              NOT NULL,
        [length]           INT              NOT NULL,
        [height]           INT              NOT NULL,
        [weight]           INT              NOT NULL,
        // more fields
        [customer_id]      INT                  CONSTRAINT [F_KEY_CUSTOMER] DEFAULT ((0)) NOT NULL,
        CONSTRAINT [P_KEY_PRODUCT] PRIMARY KEY CLUSTERED ([id] ASC),
        CONSTRAINT [F_KEY_CUSTOMER] FOREIGN KEY ([customer_id]) REFERENCES [dbo].[Customer] ([id])
    );
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查询计划

更新产品维度声明:

更新产品维度声明

更新产品声明:

更新产品声明

死锁痕迹

    <TextData>
    <deadlock-list>
    <deadlock victim="victimProcess">
    <process-list>
    <process id="victimProcess" taskpriority="0" logused="0" waitresource="PAGE: 15:1:1259" waittime="4594" ownerId="21610772296" transactionname="UPDATE" lasttranstarted="2018-02-21T08:46:44.777" XDES="0x859b9c580" lockMode="U" schedulerid="20" kpid="34240" status="suspended" spid="64" sbid="3" ecid="3" priority="0" trancount="0" lastbatchstarted="2018-02-21T08:46:44.777" lastbatchcompleted="2018-02-21T08:46:44.777" clientapp=".Net SqlClient Data Provider" hostname="" hostpid="636" isolationlevel="read committed (2)" xactid="21610772296" currentdb="15" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
        <executionStack>
        <frame procname="adhoc" line="1" stmtstart="422" sqlhandle="0x02000000696bc4026d3a5eb5fc3835e32324ce9f3e4bdd28">
    UPDATE products SET width = @width, height = @height, length = @length, customer_id = @customer_id, weight = @weight WHERE id = @id     </frame>
        <frame procname="unknown" line="1" sqlhandle="0x000000000000000000000000000000000000000000000000">
    unknown     </frame>
        </executionStack>
        <inputbuf>
        </inputbuf>
    </process>
    <process id="survivorProcess4" taskpriority="0" logused="0" waitresource="PAGE: 15:1:2795" waittime="4593" ownerId="21610772296" transactionname="UPDATE" lasttranstarted="2018-02-21T08:46:44.777" XDES="0x45ebe3ca0" lockMode="U" schedulerid="18" kpid="254204" status="suspended" spid="64" sbid="3" ecid="6" priority="0" trancount="0" lastbatchstarted="2018-02-21T08:46:44.777" lastbatchcompleted="2018-02-21T08:46:44.777" clientapp=".Net SqlClient Data Provider" hostname="" hostpid="636" isolationlevel="read committed (2)" xactid="21610772296" currentdb="15" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
        <executionStack>
        <frame procname="adhoc" line="1" stmtstart="422" sqlhandle="0x02000000696bc4026d3a5eb5fc3835e32324ce9f3e4bdd28">
    UPDATE products SET width = @width, height = @height, length = @length, customer_id = @customer_id, weight = @weight WHERE id = @id     </frame>
        <frame procname="unknown" line="1" sqlhandle="0x000000000000000000000000000000000000000000000000">
    unknown     </frame>
        </executionStack>
        <inputbuf>
        </inputbuf>
    </process>
    <process id="survivorProcess3" taskpriority="0" logused="224" waitresource="PAGE: 15:1:2795" waittime="4527" ownerId="21610772095" transactionname="UPDATE" lasttranstarted="2018-02-21T08:46:44.680" XDES="0x859b9c300" lockMode="U" schedulerid="20" kpid="16324" status="suspended" spid="123" sbid="2" ecid="1" priority="0" trancount="0" lastbatchstarted="2018-02-21T08:46:44.680" lastbatchcompleted="2018-02-21T08:46:44.673" clientapp=".Net SqlClient Data Provider" hostname="" hostpid="636" isolationlevel="read committed (2)" xactid="21610772095" currentdb="15" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
        <executionStack>
        <frame procname="adhoc" line="1" stmtstart="102" sqlhandle="0x020000007e9c95155af7dd6044d8697705c48a1d5856dba4">
    UPDATE products SET width = @width, height = @height, length = @length WHERE id = @id     </frame>
        <frame procname="unknown" line="1" sqlhandle="0x000000000000000000000000000000000000000000000000">
    unknown     </frame>
        </executionStack>
        <inputbuf>
        </inputbuf>
    </process>
    <process id="survivorProcess2" taskpriority="0" logused="224" waitresource="PAGE: 15:1:1259" waittime="4529" ownerId="21610772095" transactionname="UPDATE" lasttranstarted="2018-02-21T08:46:44.680" XDES="0x270bf8b20" lockMode="U" schedulerid="13" kpid="406864" status="suspended" spid="123" sbid="2" ecid="4" priority="0" trancount="0" lastbatchstarted="2018-02-21T08:46:44.680" lastbatchcompleted="2018-02-21T08:46:44.673" clientapp=".Net SqlClient Data Provider" hostname="" hostpid="636" isolationlevel="read committed (2)" xactid="21610772095" currentdb="15" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
        <executionStack>
        <frame procname="adhoc" line="1" stmtstart="102" sqlhandle="0x020000007e9c95155af7dd6044d8697705c48a1d5856dba4">
    UPDATE products SET width = @width, height = @height, length = @length WHERE id = @id     </frame>
        <frame procname="unknown" line="1" sqlhandle="0x000000000000000000000000000000000000000000000000">
    unknown     </frame>
        </executionStack>
        <inputbuf>
        </inputbuf>
    </process>
    <process id="survivorProcess1" taskpriority="0" logused="10000" waittime="4315" schedulerid="17" kpid="30464" status="suspended" spid="123" sbid="2" ecid="0" priority="0" trancount="2" lastbatchstarted="2018-02-21T08:46:44.680" lastbatchcompleted="2018-02-21T08:46:44.673" clientapp=".Net SqlClient Data Provider" hostname="" hostpid="636" loginname="" isolationlevel="read committed (2)" xactid="21610772095" currentdb="15" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
        <executionStack>
        <frame procname="adhoc" line="1" stmtstart="102" sqlhandle="0x020000007e9c95155af7dd6044d8697705c48a1d5856dba4">
    UPDATE products SET width = @width, height = @height, length = @length WHERE id = @id     </frame>
        <frame procname="unknown" line="1" sqlhandle="0x000000000000000000000000000000000000000000000000">
    unknown     </frame>
        </executionStack>
        <inputbuf>
    (@width int,@height int,@length int,@id nvarchar(255))UPDATE products SET width = @width, height = @height, length = @length WHERE id = @id    </inputbuf>
    </process>
    </process-list>
    <resource-list>
    <pagelock fileid="1" pageid="1259" dbid="15" objectname="MyDB.dbo.Product" id="lock15a855b00" mode="U" associatedObjectId="72057594038845440">
        <owner-list>
        <owner id="survivorProcess1" mode="U" />
        </owner-list>
        <waiter-list>
        <waiter id="victimProcess" mode="U" requestType="wait" />
        </waiter-list>
    </pagelock>
    <pagelock fileid="1" pageid="2795" dbid="15" objectname="MyDB.dbo.Product" id="lockbb9f0f80" mode="U" associatedObjectId="72057594038845440">
        <owner-list>
        <owner id="survivorProcess1" mode="U" />
        </owner-list>
        <waiter-list>
        <waiter id="survivorProcess4" mode="U" requestType="wait" />
        </waiter-list>
    </pagelock>
    <pagelock fileid="1" pageid="2795" dbid="15" objectname="MyDB.dbo.Product" id="lockbb9f0f80" mode="U" associatedObjectId="72057594038845440">
        <owner-list />
        <waiter-list>
        <waiter id="survivorProcess3" mode="U" requestType="wait" />
        </waiter-list>
    </pagelock>
    <pagelock fileid="1" pageid="1259" dbid="15" objectname="MyDB.dbo.Product" id="lock15a855b00" mode="U" associatedObjectId="72057594038845440">
        <owner-list />
        <waiter-list>
        <waiter id="survivorProcess2" mode="U" requestType="wait" />
        </waiter-list>
    </pagelock>
    <exchangeEvent id="Pipe49e4ca380" WaitType="e_waitPipeGetRow" nodeId="2">
        <owner-list>
        <owner id="survivorProcess3" />
        <owner id="survivorProcess2" />
        </owner-list>
        <waiter-list>
        <waiter id="survivorProcess1" />
        </waiter-list>
    </exchangeEvent>
    </resource-list>
    </deadlock>
    </deadlock-list>
    </TextData>
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Ric*_*imo 4

这个问题没有包含足够的场景让我能够复制这个例子，所以我要推测。

SqlCommand 是一次性的；但不在 using 块中，并且没有被释放，所以我怀疑当后续命令发生时，前一个命令仍在干扰数据库。

将两个 SqlCommand 放入“using”块中；当你这样做时，删除“finally{connection.Close();}”，并将 SqlConnection 放入“using”块中（Dispose 将执行 Close）。

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