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Type:
Bug
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Resolution: Done
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Priority:
Critical - P2
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Affects Version/s: 3.0.3, 3.0.4
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Component/s: Performance, WiredTiger
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Fully Compatible
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ALL
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Quint Iteration 7, QuInt A (10/12/15), QuInt C (11/23/15), Repl 2016-08-29, Repl 2016-09-19, Repl 2016-10-10, Repl 2016-10-31
- hardware: 24 CPUs, 64 GB memory, SSD (all mongods and clients on same machine)
- start 3-member replica set with following options:
mongod --oplogSize 50 --storageEngine wiredTiger --nojournal --replSet ...
Note: repros with journal also, ran without journal to rule out that as a cause.
- Simple small document insert workload: 5-16 threads (number doesn't matter to the repro) each inserting small documents {_id:..., x:0} in batches of 10k
Replica lag grows unbounded as secondaries process ops at maybe 50-80% the rate of the primary.
Some stats of note:
primary
secondary
- op rate on secondary is maybe half that on primary
- ops in flight (i.e. active queues) is much less even on the secondary, although that isn't reflected in the reported op rates
- secondary is executing far more search near calls, about one per document, vs what appears to be about one every 100 documents on primary
Will get stack traces.
- depends on
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- Closed
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- Closed
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SERVER-18983 Process oplog inserts, and applying, on the secondary in parallel
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- Closed
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SERVER-15344 Make replWriter thread pool size tunable
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- Closed
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- Closed
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- is duplicated by
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- Closed
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- related to
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- Closed
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- Closed
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