Java 21 on Google Cloud for Overly Enthusiastic Developers

21 is out....https://www.oracle.com/java/technologies/downloads/#jdk21-windows see https://github.com/ObrienlabsDev/blog/issues/16

Java 21 performance for BigInteger is 1.5x Java 17

The following code computes distributed collatz (3n+1) using ForkJoin using a queue of decreasing threads across all 12 vCores in this example. The sweet spot is 2x cores or 16 threads. Single core performance is at the end 11 to 2.5% faster depending on parallelization. This example was on a Xeon W-10855 2.8 to 4.5 GhZ

Longer times are worse performance

Java 17 full parallelization 6/12 cores = 14.2 sec Java 17 single core = 44.8 sec Java 21 full parallelization 6/12 cores = 12.7 sec Java 21 single core = 43.7 sec Java 21 multi core is 11% faster than Java 17 or (~5x single core improvement on a 6 core CPU) Java 21 single core is 2.5% faster than Java 17

JDK 17
PS C:\_dev> java -cp org.obrienscience.collatz.server.ForkJoinCollatzServer.jar org.obrienscience.collatz.server.ForkJoinCollatzServer 5 6 1
ForkJoinCollatzServer forkJoinPool-power-start end runs (v 20161009)
availableProc   : 12
fjps threads    : 5,6
freeMemory()    : 2141443600
maxMemory()     : 32178700288
totalMemory()   : 2147483648
Range: bits     : 25
14219,5,22,1422,8
17290,5,21,1721,16
14359,5,20,1420,32
14266,5,19,1419,64
14266,5,18,1418,128
14279,5,17,1417,256
14265,5,16,1416,512
14321,5,15,1415,1024
14297,5,14,1414,2048
14360,5,13,1413,4096
14331,5,12,1412,8192
14294,5,11,1411,16384
14314,5,10,1410,32768
14315,5,9,149,65536
14402,5,8,148,131072
14331,5,7,147,262144
14470,5,6,146,524288
14329,5,5,145,1048576
14911,5,4,144,2097152
15093,5,3,153,4194304
19489,5,2,192,8388608
33272,5,1,331,16777216
44794,5,0,440,33554432

JDK 21
PS C:\_dev> c:\jdk21\bin\java -cp org.obrienscience.collatz.server.ForkJoinCollatzServer.jar org.obrienscience.collatz.server.ForkJoinCollatzServer 5 6 1
ForkJoinCollatzServer forkJoinPool-power-start end runs (v 20161009)

17281,5,22,1722,8
20398,5,21,2021,16
12774,5,20,1220,32
12773,5,19,1219,64
12725,5,18,1218,128
12803,5,17,1217,256
12760,5,16,1216,512
12726,5,15,1215,1024
12743,5,14,1214,2048
12710,5,13,1213,4096
12741,5,12,1212,8192
12727,5,11,1211,16384
12808,5,10,1210,32768
12771,5,9,129,65536
12761,5,8,128,131072
12819,5,7,127,262144
12899,5,6,126,524288
12823,5,5,125,1048576
12916,5,4,124,2097152
12754,5,3,123,4194304
14129,5,2,142,8388608
25227,5,1,251,16777216
43744,5,0,430,33554432