Share a Hot Publisher

Create a Flux emitting "A", "B", "C" and use .share() to make it hot. Subscribe twice. Hot publishers share the execution: the second subscriber may miss items already emitted.

Note: In synchronous mode, share() typically gives both subscribers all items.

Expected

Sub1: A
Sub1: B
Sub1: C

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Main.kt

Share a Hot Publisher

medium⏱ 15 minkotlinreactorchallengehot-cold

Create a Flux emitting "A", "B", "C" and use .share() to make it hot. Subscribe twice. Hot publishers share the execution: the second subscriber may miss items already emitted.

Note: In synchronous mode, share() typically gives both subscribers all items.

Why this works

share() converts a cold publisher to a hot multicast publisher. With a synchronous source, the first subscriber triggers the full emission, and the second subscriber joins after. In async scenarios, late subscribers miss earlier events.

Expected output

Sub1: A
Sub1: B
Sub1: C

Share a Hot Publisher

Create a Flux emitting "A", "B", "C" and use .share() to make it hot. Subscribe twice. Hot publishers share the execution: the second subscriber may miss items already emitted.

Note: In synchronous mode, share() typically gives both subscribers all items.

Expected

Sub1: A Sub1: B Sub1: C

Share a Hot Publisher

medium⏱ 15 minkotlinreactorchallengehot-cold

Create a Flux emitting "A", "B", "C" and use .share() to make it hot. Subscribe twice. Hot publishers share the execution: the second subscriber may miss items already emitted.

Note: In synchronous mode, share() typically gives both subscribers all items.

Why this works

Expected output

Sub1: A Sub1: B Sub1: C