How MongoDB operate global write locking?

[Nites Bootkhot]

Hi all,
I find out about how MongoDB operate global write lock but not found.
Anyone know about it?

On writing, if MongoDB don't found data in memory, it follow steps below.

1. find Data in storage
2. take the data to memory
3. write data in memory
4. write data to storage

What step that global write lock happen?
1 - 4 ?
3 - 4 ?
Or just 3 ?


Thank you.

[Sam Millman]

I believe mongo has a db level lock now in 2.2.

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[Max Schireson]

Over the last 2 production releases, we've been working to get it to yield when it has to do i/o so that it only holds the lock during in-memory updates. That's generally the case now with 2.2; also as Sam points out it is now db level.

-- Max

[Nites Bootkhot]

As your reply, MongoDB doesn't hold locking during lookup data in harddisk.  So it's short time locking.
Thank you.
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Nites Bootkhot
Software Engineer
Intelligent Millionaire

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