[SERVER-55035] Mongo Write Lock shows 100 %, even there are no write operations shown in mongostat output Created: 08/Mar/21 Updated: 06/Dec/22 Resolved: 09/Mar/21 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Tools |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Kokila Soumi | Assignee: | Backlog - Triage Team |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Attachments: |
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| Assigned Teams: |
Server Triage
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| Operating System: | ALL |
| Steps To Reproduce: |
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| Participants: |
| Description |
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mongostats shows 100 % write lock during some specific period. However, during the same period mongotop shows zero write operations on a mongo cluster. Could you please clarify how mongostat shows 100 % write lock (lrw column) when there is no write operations seen in mongotop output !
System Configuration Os Version: CentOS 7 [sessionmgr05] out: run: df -hP -x iso9660
Attached mongotop, mongostat outputs for 100 % write lock periods.
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| Comments |
| Comment by Udaya Bhaskar chimakurthy [ 29/Mar/21 ] |
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Hi Dmitry - yes , We have upgraded the mongo to a later in the latest version of the product. However , the product in the field is running mongo db 3.4.
Kokila's question was , "lrw" column in mongostat output shows which lock %. In the use case mentioned , write lock goes to 100% , eventhough no write operations are taking place.As I understand there are various locks for various entities ( refer the link here [db.currentOp() — MongoDB Manual . Is monitoring lrw lock % recommended practice to know the health of the mongod instance. ( apart from the CPU & mem utilization ) . Can you suggest monitoring any other parameter and be assured mongod instance is hale and healthy ?
Can you please share your comments. Your response is much appreciated ! |
| Comment by Dmitry Agranat [ 09/Mar/21 ] |
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Hi kokilasoumi@gmail.com, MongoDB 3.4 reached end of life in January of 2020. For general questions like this, we'd like to encourage you to start by asking our community for help by posting on the MongoDB Developer Community Forums. |