From d106b3beb7f9069bbf00c63e7b6fcccceb97ffb6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Mierzwa?= <l.mierzwa@gmail.com>
Date: Wed, 18 Oct 2023 09:29:59 +0100
Subject: [PATCH] Wrap db.blocks read in a read lock
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We don't hold db.mtx lock when trying to read db.blocks here so we need a read lock around this loop.

Signed-off-by: Łukasz Mierzwa <l.mierzwa@gmail.com>
---
 tsdb/db.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tsdb/db.go b/tsdb/db.go
index ea8cbfff0b..001515081d 100644
--- a/tsdb/db.go
+++ b/tsdb/db.go
@@ -1518,7 +1518,9 @@ func (db *DB) compactBlocks() (err error) {
 		default:
 		}
 
+		db.mtx.RLock()
 		uids, err := db.compactor.Compact(db.dir, plan, db.blocks)
+		db.mtx.RUnlock()
 		if err != nil {
 			return fmt.Errorf("compact %s: %w", plan, err)
 		}
@@ -1601,11 +1603,13 @@ func (db *DB) reloadBlocks() (err error) {
 	if len(corrupted) > 0 {
 		// Corrupted but no child loaded for it.
 		// Close all new blocks to release the lock for windows.
+		db.mtx.RLock()
 		for _, block := range loadable {
 			if _, open := getBlock(db.blocks, block.Meta().ULID); !open {
 				block.Close()
 			}
 		}
+		db.mtx.RUnlock()
 		errs := tsdb_errors.NewMulti()
 		for ulid, err := range corrupted {
 			if err != nil {