Claude
6b5a918278
gatherers/: windowFixed, windowSliding, fold, scan, mapConcurrent, a custom Gatherer (dedupeConsecutive, takeUntil), and a Collector-vs-Gatherer comparison. Verified: windowSliding emits one short window on a too-short stream rather than shrinking to empty like windowFixed; mapConcurrent waits for in-flight siblings to finish (~901ms) rather than cancelling them when one mapper throws. scoped-values/: ScopedValue API and rebinding, why plain threads (virtual or platform) do not inherit a binding while a StructuredTaskScope subtask does, and the memory cost vs InheritableThreadLocal measured two ways -- a noisy heap-delta first pass, then a precise jcmd GC.class_histogram object census (5 shared Carrier objects vs ~700,000 copied ThreadLocalMap/Entry objects for 100,000 threads). Companion code for the ankurm.com posts "Java Stream Gatherers (JEP 485)" and "Scoped Values vs ThreadLocal in Java 25: Migration Guide with Virtual Threads". Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01FtpJvZfg4nvLvtzgJTDWpB
19 lines
1.2 KiB
Plaintext
19 lines
1.2 KiB
Plaintext
$ java MapConcurrentDemo (JDK 25)
|
|
mapConcurrent(4, ...) results, completion order reversed: [10, 20, 30, 40]
|
|
CHECK ok : mapConcurrent output preserves encounter order [10,20,30,40] even though task 1 finishes last
|
|
mapConcurrent(2, ...) over 8 tasks, peak concurrent in-flight = 2
|
|
CHECK ok : all 8 tasks completed
|
|
CHECK ok : peak in-flight never exceeded maxConcurrency=2, measured peak=2
|
|
CHECK ok : the cap is actually reached, not just respected -- measured peak=2
|
|
VirtualThread[#38]/runnable@ForkJoinPool-1-worker-2 virtual=true
|
|
VirtualThread[#39]/runnable@ForkJoinPool-1-worker-2 virtual=true
|
|
VirtualThread[#40]/runnable@ForkJoinPool-1-worker-2 virtual=true
|
|
VirtualThread[#41]/runnable@ForkJoinPool-1-worker-2 virtual=true
|
|
VirtualThread[#42]/runnable@ForkJoinPool-1-worker-2 virtual=true
|
|
VirtualThread[#37]/runnable@ForkJoinPool-1-worker-1 virtual=true
|
|
CHECK ok : every mapConcurrent worker thread reports isVirtual() == true
|
|
CHECK ok : 6 elements produced 6 distinct virtual threads -- one per element, not a shared pool
|
|
mapConcurrent propagated: boom at element 3 after 901ms
|
|
CHECK ok : the failure only surfaced after 901ms -- mapConcurrent waited for the other 4 in-flight tasks, it did not cancel them
|
|
exit=0
|