[SERVER-27425] Starting and finishing chunk migration takes Global S lock Created: 14/Dec/16 Updated: 06/Dec/22 Resolved: 15/Dec/16 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Sharding |
| Affects Version/s: | 3.0.14, 3.2.11 |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Kaloian Manassiev | Assignee: | [DO NOT USE] Backlog - Sharding Team |
| Resolution: | Won't Fix | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Assigned Teams: |
Sharding
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| Operating System: | ALL |
| Participants: | |
| Case: | (copied to CRM) |
| Description |
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In MongoDB 3.2 and earlier the shards take Global S lock during migration of chunks out of a shard. This happens both in the beginning and at completion. Given that migrations are per collection, we should be able to only use collection X or S lock instead. This problem does not apply to version 3.4 where the chunk migration code was changed significantly. |
| Comments |
| Comment by Kaloian Manassiev [ 15/Dec/16 ] |
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Due to the high risk of introducing a regression while fixing this in 3.2 and given that it has been fixed in 3.4, we won't do it in 3.2. |