Question

我在特定时间面临高CPU使用率。 4处理器，16GB RAM，29个数据库总数据文件大小为60 GB。我经常得到高线程数太高。有人可以帮我吗？

Answer 1

没有直接的解决方案。您将不得不找出导致高CPU并对其进行微调的查询。

DMV以下，为您提供消耗更多CPU的查询

SELECT TOP 50 qs.creation_time, qs.execution_count, qs.total_worker_time as total_cpu_time, qs.max_worker_time as max_cpu_time, 
qs.total_elapsed_time, qs.max_elapsed_time, qs.total_logical_reads, qs.max_logical_reads, qs.total_physical_reads, qs.max_physical_reads,t.[text], qp.query_plan, t.dbid, t.objectid, t.encrypted, qs.plan_handle, qs.plan_generation_num FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(plan_handle) AS t CROSS APPLY sys.dm_exec_query_plan(plan_handle) AS qp 
ORDER BY qs.total_worker_time DESC

此外，你说，线程数是高的。可能也是由于并行性。所以，你可能必须找出并行运行的查询。

找到它们后，找出并行执行的原因。在大多数情况下，也可能是由于缺少索引。

此查询将为您提供以下帮助：Find Query Plans That May Utilize Parallelism

SELECT
p.*,
q.*,
cp.plan_handle
FROM sys.dm_exec_cached_plans cp
CROSS APPLY sys.dm_exec_query_plan(cp.plan_handle) p
CROSS APPLY sys.dm_exec_sql_text(cp.plan_handle) q
WHERE cp.cacheobjtype = 'Compiled Plan'
AND p.query_plan.value('declare namespace p="http://schemas.microsoft.com/sqlserver/2004/07/showplan";max(//p:RelOp/@Parallel)', 'float') > 0

Answer 2

使用以下语句检查哪个数据库使用的CPU最多：

WITH DB_CPU_Stats
AS
(SELECT DatabaseID, DB_Name(DatabaseID) AS [Database Name],     SUM(total_worker_time) AS [CPU_Time_Ms]
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY (SELECT CONVERT(int, value) AS [DatabaseID]
FROM sys.dm_exec_plan_attributes(qs.plan_handle)
WHERE attribute = N'dbid') AS F_DB
GROUP BY DatabaseID)
SELECT ROW_NUMBER() OVER(ORDER BY [CPU_Time_Ms] DESC) AS [CPU Rank],
[Database Name], [CPU_Time_Ms] AS [CPU Time (ms)],
CAST([CPU_Time_Ms] * 1.0 / SUM([CPU_Time_Ms]) OVER() * 100.0 AS DECIMAL(5,2)) AS [CPU Percent]
FROM DB_CPU_Stats
WHERE DatabaseID <> 32767 -- ResourceDB
ORDER BY [CPU Rank] OPTION (RECOMPILE);

或者此语句查找哪个SQL语句使用最多的CPU

SELECT TOP 50
[Avg. MultiCore/CPU time(sec)] = qs.total_worker_time / 1000000 / qs.execution_count,
[Total MultiCore/CPU time(sec)] = qs.total_worker_time / 1000000,
[Avg. Elapsed Time(sec)] = qs.total_elapsed_time / 1000000 / qs.execution_count,
[Total Elapsed Time(sec)] = qs.total_elapsed_time / 1000000,
qs.execution_count,
[Avg. I/O] = (total_logical_reads + total_logical_writes) / qs.execution_count,
[Total I/O] = total_logical_reads + total_logical_writes,
Query = SUBSTRING(qt.[text], (qs.statement_start_offset / 2) + 1,
    (
        (
            CASE qs.statement_end_offset
                WHEN -1 THEN DATALENGTH(qt.[text])
                ELSE qs.statement_end_offset
            END - qs.statement_start_offset
        ) / 2
    ) + 1
),
Batch = qt.[text],
[DB] = DB_NAME(qt.[dbid]),
qs.last_execution_time,
qp.query_plan
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_sql_text(qs.[sql_handle]) AS qt
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) AS qp
where qs.execution_count > 5    --more than 5 occurences
ORDER BY [Total MultiCore/CPU time(sec)] DESC

第二个声明在这里找到： https://social.msdn.microsoft.com/Forums/sqlserver/en-US/33c7521f-7ed4-4574-82dd-aeb2f32111c5/find-high-cpu-query?forum=sqldatabaseengine

sqlserver2012上的高CPU使用率

2 个答案: