[MB-4578] memory spike due to growing number of replica checkpoints if some of the nodes have slow disk write Created: 26/Dec/11  Updated: 31/Jan/14  Resolved: 24/Feb/12

Status: Closed
Project: Couchbase Server
Component/s: couchbase-bucket
Affects Version/s: 1.7 GA, 1.7.1, 1.7.1.1, 1.7.2
Fix Version/s: 2.0-beta
Security Level: Public

Type: Bug Priority: Major
Reporter: Farshid Ghods (Inactive) Assignee: Chiyoung Seo
Resolution: Fixed Votes: 0
Labels: 1.8.0-release-notes, customer
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified


 Description   
a solution proposed for this issue is to coalesce checkpoints in the replica side if number of open checkpoints is more than two

https://github.com/membase/ep-engine/commit/dd4d60b79008586247e86c62e9ad2cc9320867d9

fixed in branch-17 and is going to be given to users as hotfix as need basis

 Comments   
Comment by Farshid Ghods (Inactive) [ 26/Dec/11 ]
fixed but not merged yet to 1.8 branch
Comment by Chiyoung Seo [ 26/Dec/11 ]
It was already merged into 1.8 branch. The last 1.8 build that the QA team has been testing includes this fix.
Comment by Chiyoung Seo [ 24/Feb/12 ]
We did several enhancements on the checkpoint datastructure to reduce the memory overhead.

1) Collapse multiple checkpoints into a single one
2) Each checkpoint item does not point to any Blob value instance anymore. Instead, it will always gets the latest value from memory hash table.
3) Adapt the checkpoint item datastructure and reduce its memory overhead from 88 bytes to 40 bytes.
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