storage: avoid expensive logging in MVCCAcquireLock #114773
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nvanbenschoten
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arulajmani
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Nov 22, 2023
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Reviewed 3 of 3 files at r1, 1 of 1 files at r2, all commit messages.
Reviewable status:complete! 1 of 0 LGTMs obtained (waiting on @sumeerbhola)
sumeerbhola
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This commit puts expensive logging in MVCCAcquireLock behind a log.ExpensiveLogEnabled condition. This logging was bad in two ways: 1. it was boxing structs inside of interfaces, which can cause them to allocate and risks them escaping to the heap. 2. to avoid this risk of escaping, it was prematurely calling `.String()` on them. This was expensive for the `key` value, which was being pretty-printed even when tracing was disabled. This showed up as taking 0.2% of CPU time in a run of TPC-C with Read Committed isolation. This also showed up in the new `MVCCAcquireLock_Pebble` benchmark: ``` name old time/op new time/op delta MVCCAcquireLock_Pebble/batch=false/heldOtherTxn=false/heldSameTxn=true/strength=Shared-10 4.01µs ± 3% 2.42µs ± 1% -39.70% (p=0.000 n=10+9) MVCCAcquireLock_Pebble/batch=false/heldOtherTxn=false/heldSameTxn=true/strength=Exclusive-10 4.02µs ± 2% 2.42µs ± 1% -39.75% (p=0.000 n=9+9) MVCCAcquireLock_Pebble/batch=true/heldOtherTxn=false/heldSameTxn=true/strength=Shared-10 2.92µs ± 3% 1.60µs ± 2% -45.18% (p=0.000 n=9+10) MVCCAcquireLock_Pebble/batch=true/heldOtherTxn=false/heldSameTxn=true/strength=Exclusive-10 2.91µs ± 2% 1.60µs ± 1% -45.13% (p=0.000 n=10+9) name old alloc/op new alloc/op delta MVCCAcquireLock_Pebble/batch=false/heldOtherTxn=false/heldSameTxn=true/strength=Shared-10 834B ± 0% 372B ± 0% -55.38% (p=0.000 n=10+10) MVCCAcquireLock_Pebble/batch=false/heldOtherTxn=false/heldSameTxn=true/strength=Exclusive-10 834B ± 0% 372B ± 0% -55.40% (p=0.000 n=9+10) MVCCAcquireLock_Pebble/batch=true/heldOtherTxn=false/heldSameTxn=true/strength=Shared-10 811B ± 0% 352B ± 0% -56.58% (p=0.000 n=10+10) MVCCAcquireLock_Pebble/batch=true/heldOtherTxn=false/heldSameTxn=true/strength=Exclusive-10 810B ± 0% 352B ± 0% -56.56% (p=0.000 n=10+10) name old allocs/op new allocs/op delta MVCCAcquireLock_Pebble/batch=false/heldOtherTxn=false/heldSameTxn=true/strength=Shared-10 23.0 ± 0% 8.0 ± 0% -65.22% (p=0.000 n=10+10) MVCCAcquireLock_Pebble/batch=false/heldOtherTxn=false/heldSameTxn=true/strength=Exclusive-10 23.0 ± 0% 8.0 ± 0% -65.22% (p=0.000 n=10+10) MVCCAcquireLock_Pebble/batch=true/heldOtherTxn=false/heldSameTxn=true/strength=Shared-10 22.0 ± 0% 7.0 ± 0% -68.18% (p=0.000 n=10+10) MVCCAcquireLock_Pebble/batch=true/heldOtherTxn=false/heldSameTxn=true/strength=Exclusive-10 22.0 ± 0% 7.0 ± 0% -68.18% (p=0.000 n=10+10) ``` Epic: None Release note: None
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It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR? 🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf. |
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TFTRs! bors r+ |
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This commit puts expensive logging in
MVCCAcquireLockbehind alog.ExpensiveLogEnabledcondition. This logging was bad in two ways:.String()on them. This was expensive for thekeyvalue, which was being pretty-printed even when tracing was disabled.This showed up as taking 0.17% of CPU time in a run of TPC-C with Read Committed isolation:
This also showed up in the new
MVCCAcquireLock_Pebblebenchmark, which this commit improves:Epic: None
Release note: None