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MongoDB: WiredTiger Open Cursor Count

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Can someone please explain the difference between db.serverStatus().metrics.cursor and db.serverStatus().wiredTiger.session with regards to open cursor count and open session count.?

I am seeing different values in these fields (specifically a high and increasing value for WiredTiger) and I want to be sure that I have been releasing cursors where necessary. I cannot see much information in the docs for WiredTiger.

posted Jul 20, 2015 by anonymous

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1 Answer

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The difference in the two statistics you mention is due to two factors:
* MongoDB caches WiredTiger cursors for re-use.
* WiredTiger cursors don't correspond one-to-one with MongoDB cursors.

From the perspective of your application correctness you should monitor db.serverStatus().metrics.cursor

answer Dec 8, 2015 by Manikandan J
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