1
我們有一個工作表。服務器代理作業在遊標中從該表抓取100個條目並執行一些工作。並行這個有10個服務器代理作業,其中撥打下列程序(每個都有自己的@process_id
):由事務隔離級別分隔的併發進程死鎖
CREATE PROCEDURE sp_do_workorder @process_id INT
AS
BEGIN TRY
DECLARE @wo_id NCHAR(40),
@wo_action NVARCHAR(100),
@created_at DATETIME,
@source_proc_name NVARCHAR(100),
UPDATE procedure_ctrl SET [status]='running' WHERE [procedure]='sp_do_workorder_'+CAST(@process_id AS NVARCHAR(100)) AND [status]='idle'
WHILE 1=1
BEGIN
IF NOT EXISTS (SELECT * FROM procedure_ctrl WHERE [procedure]='sp_do_workorder_'+CAST(@process_id AS NVARCHAR(100)) AND [status]='running') BREAK
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
BEGIN TRANSACTION
UPDATE workorder SET hash=CAST(@process_id AS NVARCHAR(100))
FROM workorder x
INNER JOIN (
SELECT TOP 100 id FROM workorder WHERE hash='' AND workorder_step=0 ORDER BY created_at ASC
) y ON x.id=y.id
COMMIT TRANSACTION
SET TRANSACTION ISOLATION LEVEL READ COMMITTED
DECLARE wo_cur CURSOR FAST_FORWARD FOR SELECT id,action,created_at,optin_source FROM workorder WHERE hash=CAST(@process_id AS NVARCHAR(100)) AND workorder_step=0 ORDER BY created_at ASC
OPEN wo_cur
FETCH NEXT FROM wo_cur INTO @wo_id,@wo_action,@created_at,@source_proc_name
WHILE @@FETCH_STATUS=0
BEGIN
EXEC sp_basisprozess @wo_id,@wo_action,@created_at,@source_proc_name,@process_id
FETCH NEXT FROM wo_cur INTO @wo_id,@wo_action,@created_at,@source_proc_name
END
CLOSE wo_cur
DEALLOCATE wo_cur
WAITFOR DELAY '00:00:01'
END
UPDATE procedure_ctrl SET [status]='idle' WHERE [procedure]='sp_do_workorder_'+CAST(@process_id AS NVARCHAR(100)) AND [status]='running'
END TRY
BEGIN CATCH
EXEC dbo.sp_listerror
DECLARE @error NVARCHAR(4000)
SET @error='[sp_do_workorder]_'+CAST(@process_id AS NVARCHAR(100))+': critical problem'
RAISERROR(@error, 12, 1)
END CATCH
我們得到一個真正的僵局往往大多數10個代理工作。有沒有人提示爲什麼這是這樣?爲了防止副作用,我們使用序列化事務隔離級別,因此只有一個代理作業可以抓取一個工作條目。在沒有設置事務隔離的情況下,死鎖就沒有了,但是經常發生,兩個(或更多)代理作業獲取相同的工作條目。
請參閱[使用表格作爲隊列](http://rusanu.com/2010/03/26/using-tables-as-queues/) –
聽起來不錯!我會試一試(並在稍後給出反饋) – rabudde
這似乎完全符合我們的需要,真的很棒。請回答你的評論。 – rabudde