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How It Works: Spinlock Of Type LPE_BATCH

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A question arose asking - "What does the LPE_BATCH spinlock type represent?"

You can see the LPE_* series of spinlocks using the DMV query "select * from sys.dm_os_spinlock_stats"

A spinlock is a lightweight, user mode synchronization object used to protect a specific structure. The goal of the spinlock is to be fast and efficient. So the ultimate goal is to see is 0 collisions and 0 spins. SQL Server 2008 contains 150+ spinlock objects to protect the various internal structures during multi-threaded access.

It will sound redundant but the LPE_BATCH spinlock protects the batch. For example:

select * from authors – Batch #1

go

select * from titles – Batch #2

go

I looked at a few places where LPE_BATCH is used in the code.

1. Deadlock monitor can retrieve the task and needs synchronized access to the batch’s 'Task'

2. Possible state changes on the batch – for example RUNNING, IDLE, ENQUEUED

3. Enter and Exit transaction states like DTC or MARS

 

If you are seeing collisions or spins on the LPE_BATCH spinlock I suggest you look at the before mentioned areas.  

Bob Dorr - Principal SQL Server Escalation Engineer

Comments

  • Anonymous
    August 19, 2011
    Hi Sir, I would appreciate if you can add more information about SPINLOCK.