[SERVER-18875] Oplog performance on WT degrades over time after accumulation of deleted items Created: 08/Jun/15 Updated: 22/Sep/15 Resolved: 13/Jul/15 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | WiredTiger |
| Affects Version/s: | None |
| Fix Version/s: | 3.0.5, 3.1.6 |
| Type: | Bug | Priority: | Critical - P2 |
| Reporter: | Martin Bligh | Assignee: | Martin Bligh |
| Resolution: | Done | Votes: | 0 |
| Labels: | WTcc, mms-s | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Attachments: |
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| Backwards Compatibility: | Fully Compatible | ||||||||||||||||||||||||||||||||||||
| Operating System: | ALL | ||||||||||||||||||||||||||||||||||||
| Backport Completed: | |||||||||||||||||||||||||||||||||||||
| Sprint: | Quint Iteration 5, Quint Iteration 6 | ||||||||||||||||||||||||||||||||||||
| Participants: | |||||||||||||||||||||||||||||||||||||
| Description |
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Issue Status as of Jul 14, 2015 ISSUE SUMMARY AND IMPACT WiredTiger uses a specific internal cursor to find the "beginning of the capped collection". Combined with asynchronous deletion of expired capped collection records, this is inefficient for collections with high numbers of inserts because requests have to process large number of expired documents. USER IMPACT RESOLUTION DETAILS AFFECTED VERSIONS FIX VERSION Original descriptionOver the course of 2-3 days, running a simple insert workload with hammer, the performance of inserts degrades from about 20K/s to about 4K/s. Perf indicates this:
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| Comments |
| Comment by Githook User [ 28/Aug/15 ] |
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Author: {u'username': u'keithbostic', u'name': u'Keith Bostic', u'email': u'keith@wiredtiger.com'}Message: |
| Comment by Githook User [ 29/Jun/15 ] |
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Author: {u'username': u'michaelcahill', u'name': u'Michael Cahill', u'email': u'michael.cahill@mongodb.com'}Message: |
| Comment by Githook User [ 25/Jun/15 ] |
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Author: {u'username': u'agorrod', u'name': u'Alex Gorrod', u'email': u'alexander.gorrod@mongodb.com'}Message: Merge pull request #2028 from wiredtiger/deleted-leaf-leak
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| Comment by Githook User [ 25/Jun/15 ] |
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Author: {u'username': u'michaelcahill', u'name': u'Michael Cahill', u'email': u'michael.cahill@mongodb.com'}Message: |
| Comment by Githook User [ 25/Jun/15 ] |
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Author: {u'username': u'michaelcahill', u'name': u'Michael Cahill', u'email': u'michael.cahill@mongodb.com'}Message: In particular, if we see pages marked deleted at the beginning of a capped collection, don't cache those pages if there are no possible readers other than the checkpoint itself. |
| Comment by Githook User [ 25/Jun/15 ] |
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Author: {u'username': u'michaelcahill', u'name': u'Michael Cahill', u'email': u'michael.cahill@mongodb.com'}Message: |