[SERVER-29811] extremely slow reads from secondaries after drop of unused indexes Created: 23/Jun/17 Updated: 23/Jun/17 Resolved: 23/Jun/17 |
|
| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | 3.2.12 |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Kay Agahd | Assignee: | Unassigned |
| Resolution: | Duplicate | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Attachments: |
|
||||||||||||
| Issue Links: |
|
||||||||||||
| Backwards Compatibility: | Fully Compatible | ||||||||||||
| Operating System: | ALL | ||||||||||||
| Participants: | |||||||||||||
| Description |
|
After having dropped some unused indexes through mongos, reads (using an index) from secondaries were more than 100 times slower than before (over 3000 ms). Reads from primaries were still fast as usual (1-5 ms). Since the issue persisted for over 24 hours, we restarted all secondaries, which resolved the issue immediately. I attach also the log file from one of our secondaries, called mongo-077, where you see that queries on field "offerId" became very slow after dropping the unused indexes. Our slowMs value is set to 3000 ms (instead of the default 100 ms). This is why you won't find queries on field "offerId" in the log before we dropped the unused indexes because they were always faster than 3000 ms. Mongodb version:
|
| Comments |
| Comment by Kay Agahd [ 23/Jun/17 ] |
|
Thanks Bruce for sorting this out. |
| Comment by Bruce Lucas (Inactive) [ 23/Jun/17 ] |
|
Thanks for uploading the data, and thanks for the bug report. Based on the uploaded data, it appears you are encountering
Thanks, |
| Comment by Kay Agahd [ 23/Jun/17 ] |
|
I just uploaded it here. It worked. |
| Comment by Kay Agahd [ 23/Jun/17 ] |
|
Sure, but even compressed it is 97 MB. Where can I upload it? Thanks! Btw. I misspelled the server name, it's mongo-007 and not mongo-077 - but it shouldn't matter for the bug hunt. |
| Comment by Bruce Lucas (Inactive) [ 23/Jun/17 ] |
|
In order for us to continue diagnosing this issue, can you please archive the $dbpath/diagnostic.data directory from the mongo-077 node and attach it to this ticket? Thanks, |