[SERVER-29969] MongoDB 3.2 + WiredTiger uses swap when specified cache-size is enough Created: 04/Jul/17 Updated: 29/Jul/17 Resolved: 07/Jul/17 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Admin |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | rocky | Assignee: | Mark Agarunov |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Operating System: | ALL |
| Participants: |
| Description |
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hi,
PID=5668 - Swap used : 1.24G - (mongod ) The issue: |
| Comments |
| Comment by Mark Agarunov [ 07/Jul/17 ] |
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Hello 514154167@qq.com, The ideal setting for swappiness depends on many variables that are specific to the system and setup, therefore I cannot provide a recommended value that would work best. However if you would like to reduce swap usage, setting it to a lower number, such as 10, observing how the system performs, and adjusting from there as needed is likely the best course of action. Note that swap being occupied by rarely accessed pages in not itself an issue unless you are seeing performance degradation due to this. Please note that SERVER project is for reporting bugs or feature suggestions for the MongoDB server. For MongoDB-related support discussion please post on the mongodb-user group or Stack Overflow with the mongodb tag. A question like this involving more discussion would be best posted on the mongodb-user group. Thanks, |
| Comment by rocky [ 07/Jul/17 ] |
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hi Mark, thanks |
| Comment by Mark Agarunov [ 05/Jul/17 ] |
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Hello 514154167@qq.com, Thank you for the report. From your description of the issue, I believe this may be due to the vm.swapiness value of the Linux kernel swapping out pages that haven't been recently accessed. However, to get a better idea of what may be causing this, please archive and upload the $dbPath/diagnostic.data directory. This should give a bit more information as to what is causing this. Thanks, |