thanos-io/thanos · error

mark block for deletion from bucket

Error message

mark block %s for deletion from bucket

What it means

A constructor validation guard in NewBucketCompactor: the concurrency argument (from the compactor's --compact.concurrency flag or programmatic callers) is <= 0, which would spin up no worker or panic on semaphore creation. Pure argument-validation failure with no I/O involved.

Solutions

1. Check local disk permissions and open file handles
2. Verify bucket permissions for deletion marks
3. Retry after the wrapped cause is fixed

When it happens

Trigger: Thrown at pkg/compact/compact.go:1396 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/d1e1348b93f719d7. Report an issue: GitHub.

Appendix: source

Thrown at pkg/compact/compact.go:1396

	}

	level.Info(cg.logger).Log("msg", "finished compacting blocks", "duration", time.Since(groupCompactionBegin),
		"duration_ms", time.Since(groupCompactionBegin).Milliseconds(), "result_blocks", compIDStrs, "source_blocks", sourceBlockStr)
	return true, compIDs, nil
}

func (cg *Group) deleteBlock(id ulid.ULID, bdir string, blockDeletableChecker BlockDeletableChecker) error {
	if err := os.RemoveAll(bdir); err != nil {
		return errors.Wrapf(err, "remove old block dir %s", id)
	}

	if blockDeletableChecker.CanDelete(cg, id) {
		// Spawn a new context so we always mark a block for deletion in full on shutdown.
		delCtx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
		defer cancel()
		level.Info(cg.logger).Log("msg", "marking compacted block for deletion", "old_block", id)
		if err := block.MarkForDeletion(delCtx, cg.logger, cg.bkt, id, "source of compacted block", cg.blocksMarkedForDeletion); err != nil {
			return errors.Wrapf(err, "mark block %s for deletion from bucket", id)
		}
	}
	return nil
}

// BucketCompactor compacts blocks in a bucket.
type BucketCompactor struct {
	logger                         log.Logger
	sy                             *Syncer
	grouper                        Grouper
	comp                           Compactor
	planner                        Planner
	blockDeletableChecker          BlockDeletableChecker
	compactionLifecycleCallback    CompactionLifecycleCallback
	compactDir                     string
	bkt                            objstore.Bucket
	concurrency                    int
	skipBlocksWithOutOfOrderChunks bool

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