Skip to content

Don't hold clsMu while purging stream consumers #6933

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
neilalexander merged 1 commit into from
May 30, 2025
Merged

Don't hold clsMu while purging stream consumers #6933

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 6 additions & 2 deletions locksordering.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -28,5 +28,9 @@ clearObserverState so that they cannot interleave which would leave Raft nodes i
inconsistent observer states.

jscmMu -> Account -> jsAccount
jscmMu -> stream.clsMu
jscmMu -> RaftNode
jscmMu -> stream.clsMu
jscmMu -> RaftNode

The "clsMu" lock protects the consumer list on a stream, used for signalling consumer activity.

stream -> clsMu
8 changes: 6 additions & 2 deletions server/stream.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ import (
"os"
"path/filepath"
"reflect"
"slices"
"strconv"
"strings"
"sync"
Expand Down Expand Up @@ -2267,8 +2268,12 @@ func (mset *stream) purge(preq *JSApiStreamPurgeRequest) (purged uint64, err err
fseq = ss.First
}

// Take a copy of cList to avoid o.purge() potentially taking the stream lock and
// violating the lock ordering.
mset.clsMu.RLock()
for _, o := range mset.cList {
cList := slices.Clone(mset.cList)
mset.clsMu.RUnlock()
for _, o := range cList {
start := fseq
o.mu.RLock()
// we update consumer sequences if:
Expand All @@ -2290,7 +2295,6 @@ func (mset *stream) purge(preq *JSApiStreamPurgeRequest) (purged uint64, err err
o.purge(start, lseq, isWider)
}
}
mset.clsMu.RUnlock()

return purged, nil
}
Expand Down