Prewarming

Prewarming creates and starts a named secondary runtime before a surface needs it. The runtime is ready when the first surface mounts, so the user sees no cold-start delay.

import { ThreadedRuntime } from '@react-native-runtimes/core';

await ThreadedRuntime.prewarm('conversation-release-room-runtime');

preload is an alias of prewarm:

await ThreadedRuntime.preload('conversation-release-room-runtime');

ThreadedScreen preloads its runtime by default, but that preload runs from a React effect — meaning the runtime starts at roughly the same time the screen mounts. For low-latency navigation, prewarm earlier, such as while a picker or inbox is visible:

const runtimeNames = conversations.map(
  conversation => `conversation-${conversation.id}-runtime`,
);

useEffect(() => {
  for (const runtimeName of runtimeNames) {
    void ThreadedRuntime.prewarm(runtimeName);
  }
}, [runtimeNames]);

On tap, prewarm the selected runtime again before switching screens. The call is cheap when the runtime already exists, so this is safe to do liberally:

function openConversation(conversationId: string) {
  void ThreadedRuntime.prewarm(`conversation-${conversationId}-runtime`);
  setSelectedConversationId(conversationId);
}

Native prewarm

Prewarm from native code for runtimes that should exist before any JS runs — typically your background runtime or a chat inbox.

ThreadedRuntime.prewarmRuntime(
  applicationContext,
  "conversation-release-room-runtime",
)

ThreadedRuntime.prewarmRuntime("conversation-release-room-runtime")

#include <nativecompose/threadedruntime/ThreadedRuntimeDispatcher.h>

nativecompose::threadedruntime::prewarmRuntime(
  "conversation-release-room-runtime"
);

Releasing runtimes

Destroy a named runtime when it no longer owns useful work:

await ThreadedRuntime.destroy('conversation-release-room-runtime');

For route components, set destroyOnUnmount when the screen should release the runtime immediately:

<ThreadedScreen
  component={ConversationScreen}
  destroyOnUnmount
  props={{ conversationId }}
  runtimeName={`conversation-${conversationId}-runtime`}
/>

Strategy cheat sheet