pkg/block/fetcher: fix concurrent map usage

Fixes: thanos-io#2471 This commit fixes an issue where multiple goroutines in the block fetcher filtering were concurrently accessing the same map. The goroutines were concurrently writing AND reading to the shared metas map. This commit guards this concurrent access by giving the DeduplicateFilter struct a mutex. Signed-off-by: Lucas Servén Marín <[email protected]>
squat · Apr 20, 2020 · ee24aea · ee24aea
1 parent 7c5bea6
commit ee24aea
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/pkg/block/fetcher.go b/pkg/block/fetcher.go
@@ -550,6 +550,7 @@ var _ MetadataFilter = &DeduplicateFilter{}
 // Not go-routine safe.
 type DeduplicateFilter struct {
 	duplicateIDs []ulid.ULID
+	mu           sync.Mutex
 }
 
 // NewDeduplicateFilter creates DeduplicateFilter.
@@ -603,11 +604,13 @@ func (f *DeduplicateFilter) filterForResolution(root *Node, metaSlice []*metadat
 
 	duplicateULIDs := getNonRootIDs(root)
 	for _, id := range duplicateULIDs {
+		f.mu.Lock()
 		if metas[id] != nil {
 			f.duplicateIDs = append(f.duplicateIDs, id)
 		}
 		synced.WithLabelValues(duplicateMeta).Inc()
 		delete(metas, id)
+		f.mu.Unlock()
 	}
 }