ADDITIONAL SYSTEM INFORMATION :
The problem arises in various environments:

1) Windows 11 Pro: Version 21H2, OS build 22000.675
PROCESSOR_IDENTIFIER: Intel64 Family 6 Model 142 Stepping 11, GenuineIntel
openjdk version "19-loom" 2022-09-20
OpenJDK Runtime Environment (build 19-loom+6-625)
OpenJDK 64-Bit Server VM (build 19-loom+6-625, mixed mode, sharing)

2) Linux VOG 5.10.16.3-microsoft-standard-WSL2 #1 SMP Fri Apr 2 22:23:49 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
/proc/cpuinfo:
vendor_id : GenuineIntel
cpu family : 6
model : 142
model name : Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
stepping : 11
microcode : 0xffffffff
cpu MHz : 1992.007
cache size : 8192 KB
physical id : 0
siblings : 8
core id : 0
cpu cores : 4
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 22
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology cpuid pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single ssbd ibrs ibpb stibp tpr_shadow vnmi ept vpid ept_ad fsgsbase bmi1 avx2 smep bmi2 erms invpcid rdseed adx smap clflushopt xsaveopt xsavec xgetbv1 xsaves flush_l1d arch_capabilities
vmx flags : vnmi invvpid ept_x_only ept_ad ept_1gb tsc_offset vtpr ept vpid unrestricted_guest ept_mode_based_exec
bugs : spectre_v1 spectre_v2 spec_store_bypass mds swapgs itlb_multihit srbds
bogomips : 3984.01
clflush size : 64
cache_alignment : 64
address sizes : 39 bits physical, 48 bits virtual
openjdk 19-loom 2022-09-20
OpenJDK Runtime Environment (build 19-loom+6-625)
OpenJDK 64-Bit Server VM (build 19-loom+6-625, mixed mode, sharing)

3) Linux fe3cbf72a8c1 5.4.188+ #1 SMP Sun Apr 24 10:03:06 PDT 2022 x86_64 x86_64 x86_64 GNU/Linux
/proc/cpuinfo:
vendor_id : GenuineIntel
cpu family : 6
model : 79
model name : Intel(R) Xeon(R) CPU @ 2.20GHz
stepping : 0
microcode : 0x1
cpu MHz : 2199.998
cache size : 56320 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single ssbd ibrs ibpb stibp fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm rdseed adx smap xsaveopt arat md_clear arch_capabilities
bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs taa
bogomips : 4399.99
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
power management:
openjdk 19-loom 2022-09-20
OpenJDK Runtime Environment (build 19-loom+6-625)
OpenJDK 64-Bit Server VM (build 19-loom+6-625, mixed mode, sharing)

A DESCRIPTION OF THE PROBLEM :
I am exploring capabilites of the Loom project, in particular the StructuredTaskScope and ExtentLocal (JEP 425, JDK-8286666). I wrote a piece of code which is pretty similar to the example in JavaDocs on StructuredTaskScope. The code raises the following exception:

java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:65)
at ExtentLocalBreakingDemo.lambda$doFill$1(ExtentLocalBreakingDemo.java:53)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)

Since the number of iterations before the error varies from launch to launch and depends on the N variable, I think that it could be a kind of data race on the extentLocalCache, or the actual value is lost during the context switch. If blocks (1) and (2) are swapped, the result is the same.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
java --source 19 --enable-preview --add-modules jdk.incubator.concurrent ExtentLocalBreakingDemo.java

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Iteration 0
OK
Iteration 1
OK
...
Iteration 999
OK
ACTUAL -
Iteration 0
OK
Iteration 1
OK
Iteration 2
OK
Iteration 3
OK
Iteration 4
OK
Iteration 5
OK
Iteration 6
OK
Iteration 7
OK
Iteration 8
OK
Iteration 9
OK
Iteration 10
OK
Iteration 11
OK
Iteration 12
OK
Iteration 13
OK
Iteration 14
OK
Iteration 15
OK
Iteration 16
OK
Iteration 17
OK
Iteration 18
OK
Iteration 19
OK
Iteration 20
OK
Iteration 21
OK
Iteration 22
OK
Iteration 23
OK
Iteration 24
OK
Iteration 25
OK
Iteration 26
OK
Iteration 27
OK
Iteration 28
OK
Iteration 29
OK
Iteration 30
OK
Iteration 31
OK
Iteration 32
OK
Iteration 33
OK
Iteration 34
OK
Iteration 35
OK
Iteration 36
OK
Iteration 37
OK
Iteration 38
OK
Iteration 39
OK
Iteration 40
OK
Iteration 41
VirtualThread[#83972]/runnable@ForkJoinPool-1-worker-2
java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:64)
at ExtentLocalBreakingDemo.lambda$doFill$1(ExtentLocalBreakingDemo.java:52)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)
VirtualThread[#84000]/runnable@ForkJoinPool-1-worker-2
java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:64)
at ExtentLocalBreakingDemo.lambda$doFill$1(ExtentLocalBreakingDemo.java:52)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)
VirtualThread[#84021]/runnable@ForkJoinPool-1-worker-2
java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:64)
at ExtentLocalBreakingDemo.lambda$doFill$2(ExtentLocalBreakingDemo.java:53)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)
VirtualThread[#84037]/runnable@ForkJoinPool-1-worker-2
java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:64)
at ExtentLocalBreakingDemo.lambda$doFill$2(ExtentLocalBreakingDemo.java:53)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)
VirtualThread[#83981]/runnable@ForkJoinPool-1-worker-2
java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:64)
at ExtentLocalBreakingDemo.lambda$doFill$2(ExtentLocalBreakingDemo.java:53)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)
VirtualThread[#84008]/runnable@ForkJoinPool-1-worker-2
java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:64)
at ExtentLocalBreakingDemo.lambda$doFill$1(ExtentLocalBreakingDemo.java:52)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)
Exception in thread "main" java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
at ExtentLocalBreakingDemo.lambda$fill$0(ExtentLocalBreakingDemo.java:34)
at java.base/jdk.internal.vm.ExtentLocalContainer.runWithoutScope(ExtentLocalContainer.java:114)
at java.base/jdk.internal.vm.ExtentLocalContainer.run(ExtentLocalContainer.java:100)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Carrier.run(ExtentLocal.java:327)
at ExtentLocalBreakingDemo.fill(ExtentLocalBreakingDemo.java:34)
at ExtentLocalBreakingDemo.main(ExtentLocalBreakingDemo.java:18)
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
at ExtentLocalBreakingDemo.lambda$fill$0(ExtentLocalBreakingDemo.java:34)
at java.base/jdk.internal.vm.ExtentLocalContainer.runWithoutScope(ExtentLocalContainer.java:114)
at java.base/jdk.internal.vm.ExtentLocalContainer.run(ExtentLocalContainer.java:100)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Carrier.run(ExtentLocal.java:327)
at ExtentLocalBreakingDemo.fill(ExtentLocalBreakingDemo.java:34)
at ExtentLocalBreakingDemo.main(ExtentLocalBreakingDemo.java:18)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:578)
at jdk.compiler/com.sun.tools.javac.launcher.Main.execute(Main.java:434)
at jdk.compiler/com.sun.tools.javac.launcher.Main.run(Main.java:205)
at jdk.compiler/com.sun.tools.javac.launcher.Main.main(Main.java:132)
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
at ExtentLocalBreakingDemo.lambda$doFill$2(ExtentLocalBreakingDemo.java:53)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
at java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
at java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:326)
at java.base/jdk.internal.vm.Continuation.enter(Continuation.java:319)
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
... 6 more
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
... 6 more
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
... 6 more
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
... 6 more
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
... 6 more
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
at ExtentLocalBreakingDemo.lambda$doFill$1(ExtentLocalBreakingDemo.java:52)
... 5 more
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
at ExtentLocalBreakingDemo.lambda$doFill$2(ExtentLocalBreakingDemo.java:53)
... 5 more
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.StructuredTaskScope$ShutdownOnFailure.throwIfFailed(StructuredTaskScope.java:1159)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:57)
... 6 more
Caused by: java.lang.RuntimeException: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:74)
at ExtentLocalBreakingDemo.lambda$doFill$1(ExtentLocalBreakingDemo.java:52)
... 5 more
Caused by: java.lang.NullPointerException: Cannot store to object array because "cache" is null
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.setKeyAndObjectAt(ExtentLocal.java:672)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal$Cache.put(ExtentLocal.java:636)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.slowGet(ExtentLocal.java:446)
at jdk.incubator.concurrent/jdk.incubator.concurrent.ExtentLocal.get(ExtentLocal.java:437)
at ExtentLocalBreakingDemo.doFill(ExtentLocalBreakingDemo.java:64)
... 6 more

---------- BEGIN SOURCE ----------
import java.util.concurrent.Future;
import jdk.incubator.concurrent.ExtentLocal;
import jdk.incubator.concurrent.StructuredTaskScope;

public class ExtentLocalBreakingDemo {

  private static final int ITERATIONS = 10_000;
  private static final int THRESHOLD = 64;
  private static final int N = 50_000;
  private static final ExtentLocal<int[]> DATA = ExtentLocal.newInstance();

  public static void main(String[] args) throws Exception {

    for (int i = 0; i < ITERATIONS; ++i) {
      System.out.println("Iteration " + i);
      int[] data = new int[N];

      fill(data, 42);

      for (int j = 0; j < N; ++j) {
        if (data[j] != 42) {
          System.out.println("data[" + j + "] != 42");
          System.exit(1);
        }
      }

      System.out.println("OK");
    }
  }

  private static void fill(int[] arr, int value) {
    ExtentLocal
        .where(DATA, arr)
        .run(() -> doFill(value, 0, arr.length));
  }

  private static Void doFill(int value, int begin, int end) {
    if (end <= begin) {
      return null;
    }

    if (end - begin <= THRESHOLD) {
      for (int i = begin; i != end; ++i) {
        DATA.get()[i] = value;
      }
      return null;
    }

    try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
      int middle = begin + (end - begin) / 2;

      Future<Void> left = scope.fork(() -> doFill(value, begin, middle));
      Future<Void> right = scope.fork(() -> doFill(value, middle, end));
      
      // (1) BEGIN
      scope.join();
      scope.throwIfFailed();
      // (1) END

      // (2) BEGIN
      try {
        left.get();
        right.get();
        DATA.get();
      } catch (NullPointerException e) {
        synchronized (ExtentLocalBreakingDemo.class) {
          System.err.println(Thread.currentThread());
          e.printStackTrace();
        }
        throw e;
      }
      // (2) END
    } catch (Exception e) {
      throw new RuntimeException(e);
    }

    return null;
  }
}
---------- END SOURCE ----------

FREQUENCY : always