[SERVER-27751] Mongod does not scale beyond 30 threads Created: 19/Jan/17 Updated: 22/Jan/24 |
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| Status: | Backlog |
| Project: | Core Server |
| Component/s: | Concurrency |
| Affects Version/s: | 3.4.1 |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Calvin Sze | Assignee: | Backlog - Service Architecture |
| Resolution: | Unresolved | Votes: | 3 |
| Labels: | sa-remove-fv-backlog-22 | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Assigned Teams: |
Service Arch
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| Operating System: | ALL |
| Steps To Reproduce: | We run Mongod on one socket (11 core, 88 threads with SMT8), and YCSB on another socket (11 YCSB instances to drive the workload, workload is 50% read and 50 update) |
| Participants: |
| Description |
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We have been testing our new 22 core Power machine. As usual, It is a two socket system, 11 cores in each socket, The mongotop did report that using multiple collection or database has significantly reduced the query time, but I am wondering why it does reflect to the performance, I am thinking there might be a lock in the mongod level which multiple instance or database could not break down. If it is the case what data I should collect in mongodb side to confirm that? Mongotop for multiple collection ns total read write 2017-01-17T12:31:23-05:00 ns total read write 2017-01-17T12:31:24-05:00 Monogtop for multiple database ns total read write 2017-01-17T13:15:12-05:00 Mongotop for 1 collection ns total read write 2017-01-17T12:27:36-05:00 ns total read write 2017-01-17T12:27:37-05:00 ns total read write 2017-01-17T12:27:38-05:00 |
| Comments |
| Comment by Ramon Fernandez Marina [ 19/Jan/17 ] |
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Thanks for your report calvins@us.ibm.com. There are some known issues with respect to thread scalability, in particular around specific locks (see Regards, |