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Type: Bug
Resolution: Fixed
Priority: Major - P3
Fix Version/s: 4.4.10, 5.0.4, 5.1.0-rc0
Affects Version/s: 4.2.0, 4.4.0
Component/s: Index Maintenance
Labels:
None

Backwards Compatibility:
Fully Compatible
Operating System:
ALL
Backport Requested:

v5.0, v4.4, v4.2
Sprint:
Execution Team 2021-07-26, Execution Team 2021-08-09
Case:
Linked BF Score:
137

The key insertion phase of a hybrid index build seems to hold and not yield an IX (w) lock. Any single command with an S (R) lock can block all operations during that time. In this case the offending command seems to be the read-only profile command (profile: -1)

original description

hello:
my mongo cluster is 4.2.8 with six data node.today i create index with follow command:

db.monitorIn.createIndex({ org: 1.0, et: 1.0, pbOrg: 1.0 });

index from 2020/10/22 09:58,to 10:30,all write is slow 10 times than before.it is :

Database: { acquireCount: { w: 3 }, acquireWaitCount: { w: 1 }, timeAcquiringMicros: { w: 3908088 } }.run in Index Build: inserting keys from 
external sorter into index mode,

all write is blocking.

2020-10-22T12:28:09.819+0800 I  INDEX    [conn997955] index build: inserted 439497660 keys from external sorter into index in 319 seconds.

all write is blocked time :319

from 2020-10-22T12:28:update time is 288831.

2020-10-22T12:28:10.853+0800 I  WRITE    [conn1004545] update expMonitordb.expInfos appName: "monitor_in_out" command: { q: { _id: "YT4873152410671", $or: [ { curT: { $exists: false } }, { curT: { $lt: new Date(1603336989000) } } ] }, u: { $set: { curT: new Date(1603336989000), currentOrg: "454001", currentOp: 131 } }, multi: false, upsert: false } planSummary: IXSCAN { _id: 1 } keysExamined:1 docsExamined:1 nMatched:1 nModified:1 numYields:0 queryHash:DE51A53B planCacheKey:2FB486A3 locks:{ ParallelBatchWriterMode: { acquireCount: { r: 2 } }, ReplicationStateTransition: { acquireCount: { w: 2 } }, Global: { acquireCount: { w: 2 } }, Database: { acquireCount: { w: 2 }, acquireWaitCount: { w: 1 }, timeAcquiringMicros: { w: 288830662 } }, Collection: { acquireCount: { w: 2 } }, Mutex: { acquireCount: { r: 5 } } } flowControl:{ acquireCount: 1, timeAcquiringMicros: 1 } storage:{} 288831ms