Avoid thread-local state when computing CRCs #3811
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Codecov Report
@@ Coverage Diff @@
## master #3811 +/- ##
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+ Coverage 56.31% 57.69% +1.37%
- Complexity 5524 5774 +250
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Files 473 473
Lines 40952 40963 +11
Branches 5235 5240 +5
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+ Hits 23064 23635 +571
+ Misses 15790 15211 -579
- Partials 2098 2117 +19
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codelipenghui
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Feb 27, 2023
hangc0276
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Feb 27, 2023
Ghatage
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Jul 12, 2024
### Motivation In `DigestManager` there are several accesses to ThreadLocal variable per each entry processed. The reason is the mainly due to `DigestManager` API which exposes a stateful `update()` method which can be invoked multiple times and keeps the current checksum as a thread-local variable. If we exclude MAC digest which is 20 bytes, for other digests we can instead keep the current checksum in a local variable and pass it each time, avoiding all the thread-locals and also the need for writing the checksum result into a buffer. ### Benchmarks #### Before apache#3810 ``` Benchmark (entrySize) Mode Cnt Score Error Units DigestManagerBenchmark.verifyDigest 64 thrpt 3 13.450 ± 3.634 ops/us DigestManagerBenchmark.verifyDigest 1024 thrpt 3 7.908 ± 2.637 ops/us DigestManagerBenchmark.verifyDigest 4086 thrpt 3 3.233 ± 0.882 ops/us DigestManagerBenchmark.verifyDigest 8192 thrpt 3 1.846 ± 0.047 ops/us ``` #### After apache#3810 ``` Benchmark (entrySize) Mode Cnt Score Error Units DigestManagerBenchmark.verifyDigest 64 thrpt 3 46.312 ± 7.414 ops/us DigestManagerBenchmark.verifyDigest 1024 thrpt 3 13.379 ± 1.069 ops/us DigestManagerBenchmark.verifyDigest 4086 thrpt 3 3.787 ± 0.059 ops/us DigestManagerBenchmark.verifyDigest 8192 thrpt 3 1.956 ± 0.052 ops/us ``` #### After this change ``` Benchmark (entrySize) Mode Cnt Score Error Units DigestManagerBenchmark.verifyDigest 64 thrpt 3 130.108 ± 4.854 ops/us DigestManagerBenchmark.verifyDigest 1024 thrpt 3 17.744 ± 0.238 ops/us DigestManagerBenchmark.verifyDigest 4086 thrpt 3 4.104 ± 0.181 ops/us DigestManagerBenchmark.verifyDigest 8192 thrpt 3 2.050 ± 0.066 ops/us ```
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Motivation
In
DigestManagerthere are several accesses to ThreadLocal variable per each entry processed.The reason is the mainly due to
DigestManagerAPI which exposes a statefulupdate()method which can be invoked multiple times and keeps the current checksum as a thread-local variable.If we exclude MAC digest which is 20 bytes, for other digests we can instead keep the current checksum in a local variable and pass it each time, avoiding all the thread-locals and also the need for writing the checksum result into a buffer.
Benchmarks
Before #3810
After #3810
After this change