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Type: Bug
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Resolution: Done
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Priority: Major - P3
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None
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Affects Version/s: 3.0.0-rc7, 3.0.0-rc8, 3.0.0-rc9, 3.0.0-rc10
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Component/s: Performance, Storage, WiredTiger
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Storage Execution
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Fully Compatible
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ALL
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Running ycsb with high thread count leads to low WT throughput on the 50-50 workload (Workload A). Stand-alone mogod with wiredTiger storage engine.
Seeing with that high levels of WT Rollback.
Update:
- Related to
SERVER-16662in that the problem requires many more threads than cores. Running with few cores has high performance. Running with many more thread than cores (256 on 12) leads to dramatic (50% or more) reduction in throughput. - Differs from
SERVER-16662in that the performance drop is steady (not drops to zero), and is correllated with wt transactions: transactions rolled back stat being the same level or higher than WT transaction: transactions completed.
With 3.0.0 large number of documents in not required. Issue manifests with 2M documents.
From the original description:
In the graph below, before time A there are 256 client threads. After time B there are 32 threads. Throughput is higher with 32 threads. Substantial number of rollbacks with 256 threads.
Results shown above from run with git version 7d9ec251cf0e70bc0f9bb246aacfb6e62226ad37
- is related to
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SERVER-17157 Seeing pauses in YCSB performance workload with WiredTiger
- Closed
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SERVER-16662 Extended pauses in WiredTiger when workers greatly exceeds number of cores
- Closed
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SERVER-15944 Make single-update write conflict path same as multi-update
- Closed
- related to
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SERVER-18213 Lots of WriteConflict during multi-upsert with WiredTiger storage engine
- Closed
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SERVER-19189 Improve performance under high number of threads with WT
- Closed