[webfansplz]

Background

The Rolldown UI keeps parsed session logs in an in-memory reader cache (RolldownEventsReader), capped at 32 readers by count only.

Two problems came out of that:

• Listing sessions evicted the sessions being viewed. list() created a reader for every session's meta.json. With more than 32 sessions, opening the session list pushed the loaded logs.json readers (e.g. both sides of a compare view) out of the cache, so the next interaction re-read and re-parsed the full log, which can be hundreds of MB.
• No memory bound. The cap counted readers, not data, so a few large fully-read sessions could hold several GiB.

Changes

• logs-manager.ts: session metas are parsed by a new readSessionMeta() and cached by file size + mtime, outside the reader cache. list() and the loadSession* helpers use it; deleteSession drops the cached entry. Event ids match what the events reader assigns.
• events-reader.ts: the reader cache is also bounded by total log bytes of fully read sessions (1 GiB). The two most recently used readers and readers with a pending read are never evicted. Pruning also runs after reads complete.
• Added reader-cache.test.ts covering both behaviors.

[pkg-pr-new]

Open in StackBlitz

@vitejs/devtools

npm i https://pkg.pr.new/@vitejs/devtools@634

@vitejs/devtools-kit

npm i https://pkg.pr.new/@vitejs/devtools-kit@634

@vitejs/devtools-oxc

npm i https://pkg.pr.new/@vitejs/devtools-oxc@634

@vitejs/devtools-rolldown

npm i https://pkg.pr.new/@vitejs/devtools-rolldown@634

@vitejs/devtools-vite

npm i https://pkg.pr.new/@vitejs/devtools-vite@634

@vitejs/devtools-vitest

npm i https://pkg.pr.new/@vitejs/devtools-vitest@634

commit: 935ad87

[Copilot]

🟡 Changes recommended

Concurrent-load cache pruning can dispose of a reader before its awaiting caller resumes, causing successful loads to return empty data.

1 open issue

• Cache eviction can clear data before concurrent readers resume · New

What changed in this PR

This PR separates session metadata caching from Rolldown’s log-reader cache, reducing repeated log parsing when listing sessions and limiting cached log data.

Changes:

• Cache session metadata by file size and modification time without creating log readers.
• Add a 1 GiB log-byte budget, preserving the two most recent readers and pending reads.
• Add regression tests for session-list cache retention and budget-based eviction.

File	Description
packages/​rolldown/​src/​node/​rolldown/​logs-manager.ts	Adds metadata caching and uses it across listing and session loading.
packages/​rolldown/​src/​node/​rolldown/​events-reader.ts	Adds byte-budget pruning, including pruning after reads complete.
packages/​rolldown/​src/​node/​rolldown/​__tests__/​reader-cache.test.ts	Tests cache retention and eviction protections.

_{Review effort: Balanced}