Switch to JDK 24 and use MemorySegment.copy instead of Unsafe.copyMemory

[wendigo]

No description provided.

[electrum]

I'm curious, did you run any benchmarks? We'll need to get rid of unsafe either way, but it'd be good to know if there is a big regression.

[martint]

JDK 22 is EOL. Why not 24?

[wendigo]

@electrum there is a performance regression

[wendigo]

jmh-result.json

[wendigo]

Benchmark                 (copyStrategy)     (size)   Mode  Cnt           Score          Error  Units
MemoryCopyBenchmark.copy      ARRAY_COPY          0  thrpt   10   901657389,052 ± 29132149,953  ops/s
MemoryCopyBenchmark.copy      ARRAY_COPY         32  thrpt   10   603885939,000 ± 27836132,529  ops/s
MemoryCopyBenchmark.copy      ARRAY_COPY        128  thrpt   10   279077934,981 ± 11230682,697  ops/s
MemoryCopyBenchmark.copy      ARRAY_COPY        512  thrpt   10   146525888,827 ±   824473,281  ops/s
MemoryCopyBenchmark.copy      ARRAY_COPY       1024  thrpt   10    88049470,182 ±   695551,785  ops/s
MemoryCopyBenchmark.copy      ARRAY_COPY    1048576  thrpt   10       66358,695 ±     1010,009  ops/s
MemoryCopyBenchmark.copy      ARRAY_COPY  134217728  thrpt   10         499,064 ±       10,255  ops/s
MemoryCopyBenchmark.copy           SLICE          0  thrpt   10   937358623,715 ± 21376582,130  ops/s
MemoryCopyBenchmark.copy           SLICE         32  thrpt   10   402867808,980 ±  9333573,030  ops/s
MemoryCopyBenchmark.copy           SLICE        128  thrpt   10   267096094,385 ± 19098537,804  ops/s
MemoryCopyBenchmark.copy           SLICE        512  thrpt   10   139491392,642 ±  2785986,960  ops/s
MemoryCopyBenchmark.copy           SLICE       1024  thrpt   10    89055601,674 ±   631193,010  ops/s
MemoryCopyBenchmark.copy           SLICE    1048576  thrpt   10       73376,188 ±    11678,820  ops/s
MemoryCopyBenchmark.copy           SLICE  134217728  thrpt   10         454,261 ±        6,087  ops/s
MemoryCopyBenchmark.copy     CUSTOM_LOOP          0  thrpt   10  1195460002,864 ± 12370060,410  ops/s
MemoryCopyBenchmark.copy     CUSTOM_LOOP         32  thrpt   10   409240611,269 ±  5002407,499  ops/s
MemoryCopyBenchmark.copy     CUSTOM_LOOP        128  thrpt   10   241598565,856 ±  7046155,417  ops/s
MemoryCopyBenchmark.copy     CUSTOM_LOOP        512  thrpt   10    83449657,344 ±   527316,461  ops/s
MemoryCopyBenchmark.copy     CUSTOM_LOOP       1024  thrpt   10    43169077,504 ±   477728,024  ops/s
MemoryCopyBenchmark.copy     CUSTOM_LOOP    1048576  thrpt   10       39429,141 ±      842,938  ops/s
MemoryCopyBenchmark.copy     CUSTOM_LOOP  134217728  thrpt   10         300,494 ±        7,178  ops/s
MemoryCopyBenchmark.copy          UNSAFE          0  thrpt   10   630977317,683 ±  4019456,494  ops/s
MemoryCopyBenchmark.copy          UNSAFE         32  thrpt   10   314375731,386 ± 13319636,578  ops/s
MemoryCopyBenchmark.copy          UNSAFE        128  thrpt   10   216099890,014 ±  6037883,421  ops/s
MemoryCopyBenchmark.copy          UNSAFE        512  thrpt   10   134828928,063 ±  2995346,434  ops/s
MemoryCopyBenchmark.copy          UNSAFE       1024  thrpt   10    84229060,616 ±   950809,283  ops/s
MemoryCopyBenchmark.copy          UNSAFE    1048576  thrpt   10       61078,617 ±     7460,381  ops/s
MemoryCopyBenchmark.copy          UNSAFE  134217728  thrpt   10         448,991 ±        5,766  ops/s
MemoryCopyBenchmark.copy             FFM          0  thrpt   10   874448960,464 ± 49146688,834  ops/s
MemoryCopyBenchmark.copy             FFM         32  thrpt   10   315989952,147 ± 11682953,273  ops/s
MemoryCopyBenchmark.copy             FFM        128  thrpt   10   246591525,763 ±  7902114,119  ops/s
MemoryCopyBenchmark.copy             FFM        512  thrpt   10   142302475,045 ±  3280815,814  ops/s
MemoryCopyBenchmark.copy             FFM       1024  thrpt   10    88473153,712 ±  1146379,388  ops/s
MemoryCopyBenchmark.copy             FFM    1048576  thrpt   10       64623,106 ±     7890,197  ops/s
MemoryCopyBenchmark.copy             FFM  134217728  thrpt   10         440,010 ±       15,141  ops/s

Benchmark result is saved to jmh-result.json