RxJava

Name: RxJava
Author: RxJava

Frameworks & LibrariesApache-2.0

Reactive Extensions for the JVM — composing async, event-based programs.

Latest v4.0.0-alpha-11 · Mar 25, 2026by RxJavaWritten in JavaWebsite ReactiveX/RxJava RSS

Release activity

Release activity — 11 releases across 10 days since Mar 25, 2026. Each cell is one day; darker means more releases that day. Nothing is recorded before Mar 25, 2026. Older weeks are hidden at this screen width.
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Sunday		No releases on Mar 29, 2026	No releases on Apr 5, 2026	No releases on Apr 12, 2026	No releases on Apr 19, 2026	No releases on Apr 26, 2026	No releases on May 3, 2026	No releases on May 10, 2026	No releases on May 17, 2026	No releases on May 24, 2026	No releases on May 31, 2026	No releases on Jun 7, 2026	No releases on Jun 14, 2026	No releases on Jun 21, 2026	1 release on Jun 28, 2026	No releases on Jul 5, 2026	No releases on Jul 12, 2026	No releases on Jul 19, 2026	No releases on Jul 26, 2026	No releases on Aug 2, 2026	No releases on Aug 9, 2026	No releases on Aug 16, 2026	No releases on Aug 23, 2026	No releases on Aug 30, 2026	No releases on Sep 6, 2026
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Wednesday	2 releases on Mar 25, 2026	No releases on Apr 1, 2026	No releases on Apr 8, 2026	No releases on Apr 15, 2026	No releases on Apr 22, 2026	No releases on Apr 29, 2026	No releases on May 6, 2026	No releases on May 13, 2026	No releases on May 20, 2026	No releases on May 27, 2026	No releases on Jun 3, 2026	No releases on Jun 10, 2026	No releases on Jun 17, 2026	No releases on Jun 24, 2026	No releases on Jul 1, 2026	No releases on Jul 8, 2026	No releases on Jul 15, 2026	No releases on Jul 22, 2026	No releases on Jul 29, 2026	1 release on Aug 5, 2026	No releases on Aug 12, 2026	No releases on Aug 19, 2026	No releases on Aug 26, 2026	No releases on Sep 2, 2026
Thursday	No releases on Mar 26, 2026	No releases on Apr 2, 2026	No releases on Apr 9, 2026	No releases on Apr 16, 2026	No releases on Apr 23, 2026	No releases on Apr 30, 2026	No releases on May 7, 2026	No releases on May 14, 2026	No releases on May 21, 2026	No releases on May 28, 2026	No releases on Jun 4, 2026	No releases on Jun 11, 2026	No releases on Jun 18, 2026	No releases on Jun 25, 2026	No releases on Jul 2, 2026	No releases on Jul 9, 2026	No releases on Jul 16, 2026	No releases on Jul 23, 2026	No releases on Jul 30, 2026	No releases on Aug 6, 2026	No releases on Aug 13, 2026	No releases on Aug 20, 2026	No releases on Aug 27, 2026	No releases on Sep 3, 2026
Friday	No releases on Mar 27, 2026	1 release on Apr 3, 2026	No releases on Apr 10, 2026	No releases on Apr 17, 2026	No releases on Apr 24, 2026	No releases on May 1, 2026	No releases on May 8, 2026	No releases on May 15, 2026	No releases on May 22, 2026	No releases on May 29, 2026	No releases on Jun 5, 2026	No releases on Jun 12, 2026	No releases on Jun 19, 2026	No releases on Jun 26, 2026	No releases on Jul 3, 2026	No releases on Jul 10, 2026	No releases on Jul 17, 2026	No releases on Jul 24, 2026	No releases on Jul 31, 2026	No releases on Aug 7, 2026	No releases on Aug 14, 2026	No releases on Aug 21, 2026	No releases on Aug 28, 2026	No releases on Sep 4, 2026
Saturday	No releases on Mar 28, 2026	No releases on Apr 4, 2026	No releases on Apr 11, 2026	No releases on Apr 18, 2026	No releases on Apr 25, 2026	No releases on May 2, 2026	No releases on May 9, 2026	No releases on May 16, 2026	No releases on May 23, 2026	No releases on May 30, 2026	No releases on Jun 6, 2026	No releases on Jun 13, 2026	No releases on Jun 20, 2026	No releases on Jun 27, 2026	No releases on Jul 4, 2026	1 release on Jul 11, 2026	No releases on Jul 18, 2026	No releases on Jul 25, 2026	No releases on Aug 1, 2026	No releases on Aug 8, 2026	No releases on Aug 15, 2026	No releases on Aug 22, 2026	No releases on Aug 29, 2026	No releases on Sep 5, 2026

11 releases since Mar 25, 2026, busiest day 2

Changelog

v4.0.0-alpha-21

Pre-releaseAug 5, 2026 · about 1 month ago

Added 1

Add support for JDK 28 in Gradle workflow

Changed 1

Streamable optimizations

Fixed 2

Fix FlowableCache GC issue
Fix Streamable.fromStream not closing the Stream

Security 1

Fix a privilege escalation vulnerability and spam potential via untrusted code execution in the entropy scan

From RxJava

What's Changed

Revise CONTRIBUTING.md for branch targeting and AI guidelines by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8248
Fix FlowableCache GC issue by @DragonFSKY in https://github.com/ReactiveX/RxJava/pull/8249
Add support for JDK 28 in Gradle workflow by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8251
4.x: Move TestHelper.race tests into @Isolated classes (flatMap/mergeWith batch) (#8075) by @oaksprout in https://github.com/ReactiveX/RxJava/pull/8253
4.x: Streamable optimizations 2026.07.21 by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8254
Move TestHelper.race tests into @Isolated classes: batch 2 (#8075) by @oaksprout in https://github.com/ReactiveX/RxJava/pull/8257
Fix a privilege escalation vulnerability and spam potential via untrusted code execution in the entropy scan. by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8262
Change workflow trigger from pull_request to pull_request_target by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8264
Update GitHub Actions workflow for comment posting by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8266
4.x: Fix Streamable.fromStream not closing the Stream by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8267
Update README to reflect recent changes and removals by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8265

Dependabot

chore(deps): bump github/codeql-action/upload-sarif from 4.37.1 to 4.37.2 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8243
chore(deps): bump github/codeql-action/upload-sarif from 4.37.2 to 4.37.3 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8244
chore(deps): bump ossf/scorecard-action from 2.4.3 to 2.4.4 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8245
chore(deps): bump trufflesecurity/trufflehog from 3.95.9 to 3.96.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8246
chore(deps): bump actions/setup-java from 5.6.0 to 5.7.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8256
chore(deps): bump github/codeql-action/upload-sarif from 4.37.3 to 4.37.4 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8255
chore(deps): bump gradle/actions/wrapper-validation from 6.2.0 to 6.3.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8261

New Contributors

@DragonFSKY made their first contribution in https://github.com/ReactiveX/RxJava/pull/8249
@oaksprout made their first contribution in https://github.com/ReactiveX/RxJava/pull/8253

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-20...v4.0.0-alpha-21

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v4.0.0-alpha-20

Pre-releaseJul 21, 2026 · about 2 months ago

Added 2

Streamable support for blockingLast and ignoreElements operators
Streamable support for repeat, repeatWhen, retry, and retryWhen operators

Changed 7

Optimized range and collect internals for Streamable
Optimized several operator internals for Streamable
Optimized mapOptional operator for Streamable with performance improvements
Optimized filter, map fusion, and lastOrError operators
Optimized skip operations
Optimized concatIterable and flattenAsFlowable deferred execution
Improved collect operator with IndexableSource and slow path optimizations

From RxJava

What's Changed

Implementation

4.x: Streamable + blockingLast + ignoreElements by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8231
4.x: Streamable + repeat, repeatWhen, retry, retryWhen by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8232
4.x: Streamable, improved range and collect internals + JMH by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8235
4.x: Streamable - optimize several operator internals by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8238
4.x: Streamable Operator optimizations 7/18 by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8239
4.x: Streamable mapOptional +perf by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8240

Dependabot

chore(deps): bump jupiterLauncherVersion from 6.1.1 to 6.1.2 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8233
chore(deps): bump org.junit.jupiter:junit-jupiter from 6.1.1 to 6.1.2 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8234
chore(deps): bump github/codeql-action/upload-sarif from 4.37.0 to 4.37.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8236
chore(deps): bump actions/setup-java from 5.5.0 to 5.6.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8237
chore(deps): bump actions/setup-python from 6.3.0 to 7.0.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8241
chore(deps): bump actions/checkout from 7.0.0 to 7.0.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8242

Streamable Scrabble

Ongoing measure/optimization. Managed to shave over half the time off (but some came from using better collector implementations for sure).

:computer: i9 275HX, 32GB LPDDR5 6400MT CL52, Windows 25H2, JDK 26.0.1

Step	Time (ms)	Improvement	vs Baseline
Baseline	42,5119	-	-
Avoid `whenComplete` usage in `collect`	37,566	-11,65%	-
IndexableSource in `collect`	35,815	-4,66%	-15,77%
concatIterable optimizations	31,971	-10,73%	-24,81%
map fusions	30,623	-4,22%	-27,98%
flattenAsFlowable deferred opt	27,999	-8,57%	-34,15%
MutableLong in the bench	26,159	-6,57%	-38,48%
lastOrError opt	25,164	-3,80%	-40,82%
custom `Collector` summers	24,885	-1,11%	-41,47%
skip optimizations	24,791	-0,38%	-41,69%
filter opt, filter+map fusion, lastOrError opt	23,566	-4,94%	-44,58%
slow path collect optimization	22,392	-4,98%	-47,34%
CharStreamer EnumerableSource marker	21,843	-2,45%	-48,63%
custom max collector	20,369	-6,75%	-52,09%

Versus the other techs

Tech	Time in milliseconds
For Loop JDK 26	2,125
IObservable synchronous	7,917
IEnumerable port	8,225
Ix 1.0.0	8,463
RxJava Observable 3.1.12	10,119
RxJava Observable 4a19 :arrow_backward:	10,484
RxJava Observable 2.2.21	10,612
RxJava Flowable 4a19	11,424
RxJava Flowable 3.1.12	12,499
RxJava Flowable 2.2.21	13,849
Reactive4Java 0.98.1	13,086
Guava 33.6.0	12,564
Reactor 3.8.6	14,158
CyclopsReactOpt	17,273
:new: RxJava Streamable 4a20 :arrow_backward:	20,369
JOOL 0.9.15	38,876
RxJava Streamable 4a19 :arrow_backward:	42,512

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-19...v4.0.0-alpha-20

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v4.0.0-alpha-19

Pre-releaseJul 11, 2026 · about 2 months ago

Added 7

Add Streamable.concat() method
Add Streamable.using() method
Add Streamable.take() native implementation
Add blockingFirst and blockingLast methods to Streamable
Add blockingLastOrError method to Streamable
Add skip method to Streamable
Add Single.flattenAsStreamable method

Changed 2

Replace DisposableContainer with StreamerCancellation in Streamable.stream()
Separate streamer cancellation from DisposableContainer in Streamable

From RxJava

What's Changed

API

4.x: Streamable + concat, using, test fixes by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8220
4.x: Streamable.stream() DisposableContainer -> StreamerCancellation by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8221
4.x: Streamable ~ separate streamer cancellation & DisposableContainer by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8223
4.x: Streamable ~ take native implementation by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8226 https://github.com/ReactiveX/RxJava/pull/8228
4.x: Streamable + blockingFirst, last[OrError], skip, Single.flattenAsStreamable by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8229

Dependabot

chore(deps): bump actions/setup-java from 5.4.0 to 5.5.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8222
chore(deps): bump github/codeql-action/upload-sarif from 4.36.3 to 4.37.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8225
chore(deps): bump trufflesecurity/trufflehog from 3.95.8 to 3.95.9 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8230

Misc

Add Streamable class to README base classes section by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8224
4.x: Update Readme with some small changes to trigger the beauty scanner by @akarnokd in
4.x: Fix entropy-beauty-scan wrong diff issue, via Grok by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8227

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-18...v4.0.0-alpha-19

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v4.0.0-alpha-18

Pre-releaseJul 7, 2026 · 2 months ago

Added 10

Add Streamable API with range, fromArray, take, error, and defer operators
Add Streamable operators fromIterable, fromStream, hide, and never
Add Streamable operators map, filter, and flatMap
Add Streamable operators doOnNext, intercept, lift, and to
Add Streamable operators timer and interval
Add Streamable operators takeWhile, toObservable, and toStreamable conversion
Add Streamable operators takeUntil and groupBy
Add Streamable operators delay, timeout, zip, and onErrorResumeNext
Add DispatchStreamProcessor to Streamable API
Add Streamable operators doOnError and forEach(StreamSink)

Changed 2

Rework Streamable and Streamer API by dropping next and finish arguments
Convert test framework from JUnit 4 to JUnit 6

Fixed 1

Fix SchedulerToExecutorService invokeAll and invokeAny implementation

From RxJava

API

4.x: Streamable + range, fromArray, take, error, defer by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8206
4.x: Streamable + fromIterable, fromStream, hide, never, fixes by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8207
4.x: Streamable + map, filter, flatMap impl, fixes and reworks by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8208
4.x: Streamable Ops: doOnNext, intercept, lift, to; test cleanup by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8209
4.x: Streamable/Streamer API rewamp, dropping next/finish args by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8212
4.x: Streamable + timer + interval; cleanups by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8213
4.x: Streamable + takeWhile, + fromXXX, + toObservable + ~.toStreamble by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8214
4.x: Streamable + takeUntil + groupBy + refactor + helpers by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8215
4.x: Streamable + delay, timeout, zip, onErrorResumeNext, cleanup by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8216
4.x: Streamable + DispatchStreamProcessor & other improvements by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8217
4.x: Streamable + doOnError, forEach(StreamSink) by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8218

Test

4.x: Add VirtualSchedulerTests extends AbstractSchedulerConcurrencyTests by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8204

Fixes

4.x: Fix SchedulerToExecutorService invokeAll and invokeAny impl by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8205

Cleanup

4.x: Convert from JUnit 4 to JUnit 6 by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8202
4.x: Remove Pioneer-RetryTest as it is itself flaky?! by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8203

Dependabot

chore(deps): bump trufflesecurity/trufflehog from 3.95.6 to 3.95.7 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8201
chore(deps): bump trufflesecurity/trufflehog from 3.95.7 to 3.95.8 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8210
chore(deps): bump github/codeql-action/upload-sarif from 4.36.2 to 4.36.3 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8211

Documentation

4.x: What's different in 4.0 documentation, start by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8219

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-17...v4.0.0-alpha-18

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v4.0.0-alpha-17

Pre-releaseJun 29, 2026 · 2 months ago

Changed 3

Standardize config records into 3 main variants
Reduce Flowable API: concat*, merge, concatMap*, flatMap* operators
Reduce Flowable API: remaining operators and related changes

From RxJava

What's Changed

API reductions

4.x: Standardize config records into 3 main variants by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8194
4.x: Flowable API reduction: concat*, merge, concatMap*, flatMap* by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8195
4.x: Flowable API reduction: remaining operators & other related changes by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8200

Dependabot

chore(deps): bump jupiterLauncherVersion from 6.1.0 to 6.1.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8199
chore(deps): bump actions/cache from 6.0.0 to 6.1.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8197
chore(deps): bump jupiterVersion from 6.1.0 to 6.1.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8198

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-16...v4.0.0-alpha-17

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v4.0.0-alpha-16

Pre-releaseJun 28, 2026 · 2 months ago

Fixed 1

Fix NullPointerException in AppendOnlyLinkedArrayList.forEachWhile on a full last chunk

Removed 12

Single.concat and Single.concatEager methods
Single.merge method
Maybe.concat, Maybe.concatEager, and Maybe.merge methods
Observable.combineLatest method
Observable.concat method
Observable.merge method
Observable.concatEager method
Observable.sequenceEqual, Observable.switchOnNext, and Observable.zip methods
Observable.concatArray, Observable.concatEager, and related concat variants
Observable.flatMap variants, Observable.groupBy, and Observable.observeOn methods
Observable.switchMap method
Disposable no longer implements AutoCloseable

From RxJava

What's Changed

API reductions

4.x: Single API reduction: concat & concatEager by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8167
4.x: Single API reduction: merge by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8168
4.x: Maybe API reduction: concat, concatEager, merge by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8169
4.x: Observable API reduction: combineLatest by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8172
4.x: Observable API reduction: concat by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8175
4.x: Observable API reduction: merge by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8176
4.x: Observable API reduction: concatEager by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8177
4.x: Observable API reduction: sequenceEqual, switchOnNext, zip by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8190
4.x: Observable API reduction: concat { Array, Eager, XYZ } by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8191
4.x: Observable API reduction: flatMap*, groupBy, observeOn by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8192
4.x: Observable API reduction: Observable.switchMap by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8193

Other API changes

4.x: Disposable no longer impls AutoCloseable by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8184

Cleanup

4.x: Cleanup + lambda instead of inner class check by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8179
4.x: Cleanup: Serial annotation, getFirst usage by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8180
4.x: Cleanup; build, safevarargs, small typos by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8183
4.x: Cleanup - Migration; lambdas expressions by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8188
4.x: Cleanup, fix inferable types via var or diamond by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8189
4.x: Cleanup, Java Migration; records, newer API, newer syntax by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8187
4.x: Cleanup: convert anonymous inner classes to lambdas in test files by @GautamKumarOffical in https://github.com/ReactiveX/RxJava/pull/8178
4.x: Cleanup, wording minor things by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8186

Bugfixes

Fix NullPointerException in AppendOnlyLinkedArrayList.forEachWhile on a full last chunk by @vasiliy-mikhailov in https://github.com/ReactiveX/RxJava/pull/8174
- Note on the contributor: Banned, AI Slop, Undisclosed AI Use, Had to Manually Correct PR
- Contributing.md clearly states we (I) won't argue with your AI to fix the PR style or content or whatever.

Dependabot

chore(deps): bump actions/setup-java from 5.3.0 to 5.4.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8182
chore(deps): bump actions/cache from 5.0.5 to 6.0.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8170
chore(deps): bump actions/setup-python from 6.2.0 to 6.3.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8171

New Contributors

@GautamKumarOffical made their first contribution in https://github.com/ReactiveX/RxJava/pull/8178

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-15...v4.0.0-alpha-16

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v4.0.0-alpha-15

Pre-releaseJun 23, 2026 · 3 months ago

Changed 1

Turn Completable concatX and mergeX into config-based API

Fixed 1

Fix IllegalStateException in SchedulerToExecutorService.invokeAny

From RxJava

What's Changed

Fixes & Enhancements

Fix IllegalStateException in SchedulerToExecutorService.invokeAny by @vasiliy-mikhailov in https://github.com/ReactiveX/RxJava/pull/8159
4.x: API turn Completable concatX and mergeX into config-based by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8166

Cleanup

4.x: Unit test lambdaification 14 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8155
4.x: Unit test lambdaification 15 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8156
4.x: Unit test lambdaification 16 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8157
4.x: Unit test lambdaification 17 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8158
4.x: Unit test lambdaification 18 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8160
4.x: Unit test lambdaification 19 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8161
4.x: Unit test lambdaification 20 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8162
4.x: Unit test lambdaification 21 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8163
4.x: Unit test lambdaification 22 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8164
4.x: Unit test lambdaification 23 of 23 by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8165

Chores

None

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-14...v4.0.0-alpha-15

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v4.0.0-alpha-14

Pre-releaseJun 22, 2026 · 3 months ago

Added 3

Detect un-awaited CompletionStageDisposables during tests
Add task coordination primitives and implement a basic concat() operator
Add +shared, +parallel, +blocking Scheduler

Changed 1

Fix Scheduler.toExecutorService(boolean) logic

Fixed 1

Fix Scheduler.toExecutorService() NullPointerException from null worker store

Removed 1

Remove Scheduler.when due to maintenance burden

From RxJava

What's Changed

4.x: Detect un-awaited CompletionStageDisposables during tests by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8093
4.x: Add task coordination primitives, implement a basic concat() operator by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8110
Fix Scheduler.toExecutorService() NullPointerException from null worker store by @vasiliy-mikhailov in https://github.com/ReactiveX/RxJava/pull/8149
4.x: Scheduler.toExecutorService(boolean) logic fix by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8151
4.x: Remove Scheduler.when due to maintenance burden by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8153
4.x: +shared, +parallel, +blocking Scheduler by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8154

Chores

chore(deps): bump gradle/actions from 6.0.1 to 6.1.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8095
chore(deps): bump actions/github-script from 8 to 9 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8099
chore(deps): bump trufflesecurity/trufflehog from 3.94.2 to 3.94.3 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8098
chore(deps): bump SethCohen/github-releases-to-discord from 1.19.0 to 1.20.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8096
chore(deps): bump actions/cache from 5.0.4 to 5.0.5 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8102
chore(deps): bump com.google.guava:guava from 33.5.0-jre to 33.6.0-jre by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8103
chore(deps): bump actions/upload-artifact from 7.0.0 to 7.0.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8101
chore(deps): bump github/codeql-action from 4.35.1 to 4.35.2 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8104
chore(deps): bump trufflesecurity/trufflehog from 3.94.3 to 3.95.2 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8105
chore(deps): bump gradle-wrapper from 9.4.1 to 9.5.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8106
chore(deps): bump github/codeql-action from 4.35.2 to 4.35.3 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8109
chore(deps): bump github/codeql-action from 4.35.3 to 4.35.4 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8111
chore(deps): bump gradle-wrapper from 9.5.0 to 9.5.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8113
chore(deps): bump trufflesecurity/trufflehog from 3.95.2 to 3.95.3 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8112
chore(deps): bump github/codeql-action from 4.35.4 to 4.35.5 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8114
chore(deps): bump codecov/codecov-action from 6.0.0 to 6.0.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8115
test: simplify SingleRetryTest callables by @puneetdixit200 in https://github.com/ReactiveX/RxJava/pull/8120
chore(deps): bump github/codeql-action from 4.35.5 to 4.36.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8121
chore(deps): bump biz.aQute.bnd.builder from 7.2.3 to 7.3.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8126
chore(deps): bump trufflesecurity/trufflehog from 3.95.3 to 3.95.5 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8125
chore(deps): bump actions/checkout from 6.0.2 to 6.0.3 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8124
chore(deps): bump github/codeql-action from 4.36.0 to 4.36.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8123
chore(deps): bump github/codeql-action from 4.36.1 to 4.36.2 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8127
chore(deps): bump codecov/codecov-action from 6.0.1 to 7.0.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8129
chore(deps): bump gradle/actions from 6.1.0 to 6.1.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8130
chore(deps): bump jupiterLauncherVersion from 6.0.3 to 6.1.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8116
chore(deps): bump jupiterVersion from 6.0.3 to 6.1.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8117
chore(deps): bump gradle/actions from 6.1.1 to 6.2.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8131
chore(deps): bump EnricoMi/publish-unit-test-result-action from 2.23.0 to 2.24.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8132
chore(deps): bump gradle-wrapper from 9.5.1 to 9.6.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8134
chore(deps): bump trufflesecurity/trufflehog from 3.95.5 to 3.95.6 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8135
chore(deps): bump actions/checkout from 6.0.3 to 7.0.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8136
chore(deps): bump actions/setup-java from 5.2.0 to 5.3.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8133
chore(deps): bump com.vanniktech.maven.publish from 0.36.0 to 0.37.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8148

Cleanup

4.x: Unit test lambdaification 1 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8137
4.x: Unit test lambdaification 2 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8138
4.x: Unit test lambdaification 3 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8139
4.x: Unit test lambdaification 4 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8140
4.x: Unit test lambdaification 5 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8141
4.x: Unit test lambdaification 6 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8142
4.x: Unit test lambdaification 7 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8143
4.x: Unit test lambdaification 8 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8144
4.x: Unit test lambdaification 9 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8145
4.x: Unit test lambdaification 10 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8146
4.x: Unit test lambdaification 11 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8147
4.x: Unit test lambdaification 12 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8150
4.x: Unit test lambdaification 13 of N by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8152

New Contributors

@puneetdixit200 made their first contribution in https://github.com/ReactiveX/RxJava/pull/8120
@vasiliy-mikhailov made their first contribution in https://github.com/ReactiveX/RxJava/pull/8149

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-13...v4.0.0-alpha-14

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v4.0.0-alpha-13

Pre-releaseApr 3, 2026 · 5 months ago

Added 1

Optional build and test support for future JDKs

Changed 1

Enhance Streamable, Streamer, and DisposableContainer APIs

Fixed 1

Isolate windowUnsubscribeNonOverlappingAsyncSource test to JUnit 5

From RxJava

What's Changed

4.x: Add optional build/test for future JDKs by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8077
4.x: Isolate FlowableMergeTest.synchronizationOfMultipleSequencesLoop by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8078
chore(deps): bump codecov/codecov-action from 5.5.3 to 6.0.0 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8085
Fix #8086: Isolate windowUnsubscribeNonOverlappingAsyncSource to JUnit 5 by @ZhangDT-sky in https://github.com/ReactiveX/RxJava/pull/8087
chore(deps): bump github/codeql-action from 4.34.1 to 4.35.1 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8088
chore(deps): bump trufflesecurity/trufflehog from 3.94.1 to 3.94.2 by @dependabot[bot] in https://github.com/ReactiveX/RxJava/pull/8091
4.x: Enhance Streamable/Streamer and DisposableContainer APIs by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8092

New Contributors

@ZhangDT-sky made their first contribution in https://github.com/ReactiveX/RxJava/pull/8087

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-11...v4.0.0-alpha-13

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v4.0.0-alpha-12

Pre-releaseMar 25, 2026 · 6 months ago

Added 1

Add optional build and test support for future JDKs

From RxJava

What's Changed

4.x: Add optional build/test for future JDKs by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8077

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-11...v4.0.0-alpha-12

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v4.0.0-alpha-11

LatestMar 25, 2026 · 6 months ago

Changed 1

Upgrade to Java 26 baseline compilation

From RxJava

What's Changed

4.x: Upgrade to Java 26 baseline compilation, test isolation by @akarnokd in https://github.com/ReactiveX/RxJava/pull/8074

Full Changelog: https://github.com/ReactiveX/RxJava/compare/v4.0.0-alpha-10...v4.0.0-alpha-11

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