0811409ca3
Motivation: This PR fixes some non-negligible overhead discovered in the ByteBuf accessibility (non-zero refcount) checking. The cause turned out to be mostly twofold: - Unnecessary operations used to calculate the refcount from the "raw" encoded int field value - Call stack depths exceeding the default limit for inlining, in some places (CompositeByteBuf in particular) It's a follow-on from #8882 which uses the maxCapacity field for a simpler non-negative check. The performance gap between these two variants appears to be _mostly_ closed, but there's one exception which may warrant further analysis. Modifications: - Replace ABB.internalRefCount() with ByteBuf.isAccessible(), the default still checks for non-zero refCnt() - Just test for parity of raw refCnt instead of converting to "real", with fast-path for specific small values - Make sure isAccessible() is delegated by derived/wrapper ByteBufs - Use existing freed flag in CompositeByteBuf for faster isAccessible() - Manually inline some calls in methods like CompositeByteBuf.setLong() and AbstractReferenceCountedByteBuf.isAccessible() to reduce stack depths (to ensure default inlining limit isn't hit) - Add ByteBufAccessBenchmark which is an extension of UnsafeByteBufBenchmark (maybe latter could now be removed) Results: Before: Benchmark (bufferType) (checkAccessible) (checkBounds) Mode Cnt Score Error Units readBatch UNSAFE true true thrpt 30 84524972.863 ± 518338.811 ops/s readBatch UNSAFE_SLICE true true thrpt 30 38608795.037 ± 298176.974 ops/s readBatch HEAP true true thrpt 30 80003697.649 ± 974674.119 ops/s readBatch COMPOSITE true true thrpt 30 18495554.788 ± 108075.023 ops/s setGetLong UNSAFE true true thrpt 30 247069881.578 ± 10839162.593 ops/s setGetLong UNSAFE_SLICE true true thrpt 30 196355905.206 ± 1802420.990 ops/s setGetLong HEAP true true thrpt 30 245686644.713 ± 11769311.527 ops/s setGetLong COMPOSITE true true thrpt 30 83170940.687 ± 657524.123 ops/s setLong UNSAFE true true thrpt 30 278940253.918 ± 1807265.259 ops/s setLong UNSAFE_SLICE true true thrpt 30 202556738.764 ± 11887973.563 ops/s setLong HEAP true true thrpt 30 280045958.053 ± 2719583.400 ops/s setLong COMPOSITE true true thrpt 30 121299806.002 ± 2155084.707 ops/s After: Benchmark (bufferType) (checkAccessible) (checkBounds) Mode Cnt Score Error Units readBatch UNSAFE true true thrpt 30 101641801.035 ± 3950050.059 ops/s readBatch UNSAFE_SLICE true true thrpt 30 84395902.846 ± 4339579.057 ops/s readBatch HEAP true true thrpt 30 100179060.207 ± 3222487.287 ops/s readBatch COMPOSITE true true thrpt 30 42288494.472 ± 294919.633 ops/s setGetLong UNSAFE true true thrpt 30 304530755.027 ± 6574163.899 ops/s setGetLong UNSAFE_SLICE true true thrpt 30 212028547.645 ± 14277828.768 ops/s setGetLong HEAP true true thrpt 30 309335422.609 ± 2272150.415 ops/s setGetLong COMPOSITE true true thrpt 30 160383609.236 ± 966484.033 ops/s setLong UNSAFE true true thrpt 30 298055969.747 ± 7437449.627 ops/s setLong UNSAFE_SLICE true true thrpt 30 223784178.650 ± 9869750.095 ops/s setLong HEAP true true thrpt 30 302543263.328 ± 8140104.706 ops/s setLong COMPOSITE true true thrpt 30 157083673.285 ± 3528779.522 ops/s There's also a similar knock-on improvement to other benchmarks (e.g. HPACK encoding/decoding) as shown in #8882. For sanity I did a final comparison of the "fast path" tweak using one of the HPACK benchmarks: (rawCnt & 1) == 0: Benchmark (limitToAscii) (sensitive) (size) Mode Cnt Score Error Units HpackDecoderBenchmark.decode true true MEDIUM thrpt 30 50914.479 ± 940.114 ops/s rawCnt == 2 || rawCnt == 4 || rawCnt == 6 || rawCnt == 8 || (rawCnt & 1) == 0: Benchmark (limitToAscii) (sensitive) (size) Mode Cnt Score Error Units HpackDecoderBenchmark.decode true true MEDIUM thrpt 30 60036.425 ± 1478.196 ops/s |
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