[SERVER-8049] Very short timeout for select() call in net listener eats up CPU time Created: 29/Dec/12 Updated: 22/Jan/13 Resolved: 30/Dec/12 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Internal Code, Networking, Performance |
| Affects Version/s: | 1.9.2, 2.0.8, 2.1.2, 2.2.2, 2.3.1 |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Minor - P4 |
| Reporter: | Calvin Owens | Assignee: | Unassigned |
| Resolution: | Duplicate | Votes: | 0 |
| Labels: | performance | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Environment: |
Linux |
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| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||
| Operating System: | ALL | ||||||||
| Steps To Reproduce: | Run strace on idle mongod - see 100 select() calls each second. Top will show CPU usage. |
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| Participants: | |||||||||
| Description |
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The select() call at src/mongo/util/net/listen.cpp:218 is made with a timeout of 10ms, which is unnecessarily small, and, on one of my machines, results in a constant CPU consumption of >1% when mongod is sitting idle. Eliminate the timeout altogether: just pass NULL and let select() block until something happens. The timeout specified here is unnecessary, as a timeout simply results in select() being called again. |
| Comments |
| Comment by Eliot Horowitz (Inactive) [ 30/Dec/12 ] |
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No problem. |
| Comment by Calvin Owens [ 30/Dec/12 ] |
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Sorry for the noise |
| Comment by Eliot Horowitz (Inactive) [ 30/Dec/12 ] |
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The timeout loop has multiple purposes, so its not trivial to remove. |
| Comment by Eliot Horowitz (Inactive) [ 30/Dec/12 ] |
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See |