risingwavelabs/risingwave · critical

Failed to retrieve fragment description: fragment {} (job_id

Error message

Failed to retrieve fragment description: fragment {} (job_id {}) not found in shared actor info

What it means

get_fragment_desc_by_id reads the fragment row from the database, then looks up the live fragment/actor info in the in-memory shared actor info cache. The error (a panic via unwrap_or_else) means the DB still has the fragment but the shared-actor-info snapshot no longer holds it, i.e. cache and database are out of sync.

Source

Thrown at src/meta/src/controller/fragment.rs:582

        let upstreams: Vec<_> = upstream_entries
            .into_iter()
            .map(|(source_id, _)| source_id)
            .collect();

        let root_fragment_map = find_fragment_no_shuffle_dags_detailed(&inner.db, &[fragment_id])
            .await
            .map(Self::collect_root_fragment_mapping)?;
        let root_fragments = root_fragment_map
            .get(&fragment_id)
            .cloned()
            .unwrap_or_default();

        let info = self.env.shared_actor_infos().read_guard();
        let SharedFragmentInfo { actors, .. } = info
            .get_fragment(fragment_model.fragment_id as _)
            .unwrap_or_else(|| {
                panic!(
                    "Failed to retrieve fragment description: fragment {} (job_id {}) not found in shared actor info",
                    fragment_model.fragment_id,
                    fragment_model.job_id
                )
            });

        let parallelism_policy = Self::format_fragment_parallelism_policy(
            fragment_model.distribution_type,
            fragment_model.parallelism.as_ref(),
            job_parallelism.as_ref().map(|(parallelism, _)| parallelism),
            job_parallelism
                .as_ref()
                .and_then(|(_, strategy)| strategy.as_deref()),
            &root_fragments,
        );

        let fragment = FragmentDesc {
            fragment_id: fragment_model.fragment_id,

View on GitHub (pinned to 6469eb736d)

Solutions

1. Verify the streaming job still exists (not being dropped) before querying its fragments
2. Retry after a short delay if a concurrent DDL may be in flight
3. Inspect meta node logs for shared actor info eviction/rebuild events around the failure time
4. If reproducible after restart, check that actor deployment completion persists shared fragment info before responding to the DDL

Example fix

// before
let info = shared_actor_infos().read_guard().get_fragment(fid).unwrap_or_else(|| panic!(...));
// after
let info = shared_actor_infos().read_guard().get_fragment(fid).ok_or_else(|| MetaError::fragment_not_found(fid))?;

// caller: check job still exists before fetching fragments
let exists = StreamingJob::find_by_id(job_id).one(&db).await?.is_some();

fn fragment_in_shared_info(guard: &SharedActorInfos, fid: FragmentId) -> bool { guard.get_fragment(fid).is_some() }

match get_fragment_desc_by_id(job_id).await { Ok(d) => d, Err(e) if e.to_string().contains("not found in shared actor info") => retry_or_skip(job_id), Err(e) => return Err(e) }

When it happens

Trigger: Calling FragmentManager::get_fragment_desc_by_id for a fragment_id whose fragment exists in the fragments table but was evicted/never inserted into shared actor info — e.g. querying during job deletion, or before the job's actors were published to the cache.

Common situations: Frontend fetching fragment descriptions while a DDL (drop/backfill cancel) is concurrently removing the job's actors; querying right after meta recovery when shared actor info was rebuilt from incomplete data; debugging tools hitting fragments of already-dropped streaming jobs.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

• Some streaming jobs already exist in meta, please start with
• invalid parallelism
• fragment {} not found in shared actor info
• expected exactly one mview fragment for job {}, found {}
• failed to parse relation definition

AI-assisted analysis of risingwavelabs/risingwave@6469eb736d (2026-09-11). Data as JSON: /api/errors/745c94194ac0e5a9. Report an issue: GitHub.