Details
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Bug
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Resolution: Fixed
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Major
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6.6.0, 6.6.1, 6.6.2, 6.6.3, 6.6.4, 6.6.5, 7.0.0, 7.0.1, 7.0.2, 7.0.3, 7.0.4, 7.1.0, 7.1.1
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Security Level: Public
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Untriaged
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1
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No
Description
- XDCR receives ENOMEM and prepares the packet for resend (http://src.couchbase.org/source/xref/6.6.2/goproj/src/github.com/couchbase/goxdcr/parts/xmem_nozzle.go#2041)
- Leading to this call to get bytes: http://src.couchbase.org/source/xref/6.6.2/goproj/src/github.com/couchbase/goxdcr/parts/xmem_nozzle.go#2426-2427
- At first glance, the above looks to be using a slice reference, but digging into gomemcached…
- http://src.couchbase.org/source/xref/6.6.2/godeps/src/github.com/couchbase/gomemcached/mc_req.go#104-118 <- this call actually make copies of the data
So even if the stats do not move (i.e. the analysis I’ve shown), and yet target keeps returning ENOMEM (and potentially TMPFAIL), XDCR will keep retrying to resend…. but each resend actually allocates memory instead of reusing existing ones.
| Issue | Resolution |
| When target data nodes were undersized or consistently overwhelmed, XDCR memory usages could increase as it retried. | Reallocated memory is now reused instead of generate garbage for GC to clean up. |
Attachments
Issue Links
- backports to
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- Closed
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| For Gerrit Dashboard: MB-56850 | ||||||
|---|---|---|---|---|---|---|
| # | Subject | Branch | Project | Status | CR | V |
| 190931,1 | MB-56850: reuse allocated byte slice when retrying due to target temp errors | 7.1.4 | goxdcr | Status: ABANDONED | 0 | 0 |
| 192045,2 | MB-56850: reuse allocated byte slice when retrying due to target temp errors | 7.1.x | goxdcr | Status: MERGED | +2 | +1 |