t8y2/dbx · error

agent session limit reached: %d

Error message

agent session limit reached: %d

What it means

Returned by runtimeServer.openSession in the kingbase-go driver when the number of open sessions is already at maxAgentSessions. New sessions are refused (after the duplicate-id check) to bound resource usage; existing sessions remain usable.

Source

Thrown at agents/drivers/kingbase-go/main.go:293

		session, err := r.session(id)
		if err != nil {
			return nil, false, err
		}
		session.mu.Lock()
		defer session.mu.Unlock()
		return session.server.dispatch(method, params)
	}
}

func (r *runtimeServer) openSession(id string, cp connectParams) error {
	r.mu.Lock()
	if _, exists := r.sessions[id]; exists {
		r.mu.Unlock()
		return fmt.Errorf("agent session already exists: %s", id)
	}
	if len(r.sessions) >= maxAgentSessions {
		r.mu.Unlock()
		return fmt.Errorf("agent session limit reached: %d", maxAgentSessions)
	}
	r.mu.Unlock()

	s := newServer()
	if err := s.connect(cp); err != nil {
		return err
	}
	r.mu.Lock()
	defer r.mu.Unlock()
	if _, exists := r.sessions[id]; exists {
		_ = s.disconnect()
		return fmt.Errorf("agent session already exists: %s", id)
	}
	r.sessions[id] = &agentSession{server: s}
	return nil
}

func (r *runtimeServer) session(id string) (*agentSession, error) {

View on GitHub (pinned to c0390bff16)

Solutions

1. Ensure every opened session is closed (defer closeSession) including on error paths
2. Raise maxAgentSessions if the workload legitimately needs more concurrent sessions
3. Audit for session leaks: log open/close pairs and count active sessions
4. Reuse/pool sessions instead of opening one per operation

Example fix

// before: no close on error
s, err := rt.OpenSession(id, cp)
if err != nil { return err }
// after: guarantee cleanup
s, err := rt.OpenSession(id, cp)
if err != nil { return err }
defer rt.CloseSession(id)

// Go: check current session count against cap before opening
if len(rt.ListSessionIDs()) >= maxAgentSessions {
    return fmt.Errorf("at session cap; close sessions before opening more")
}

err := rt.OpenSession(id, cp)
if err != nil && strings.Contains(err.Error(), "limit reached") {
    rt.CloseOldestIdleSession() // reclaim capacity
    err = rt.OpenSession(id, cp)
}

When it happens

Trigger: Opening more than maxAgentSessions distinct session ids without closing any — e.g. a workload that creates a session per request and never calls close/shutdown.

Common situations: Long-running agents leaking sessions on error paths (connect fails after reservation is skipped, or close is never called); parallel test suites each opening sessions; tight maxAgentSessions configured for large fan-out workloads.

Related errors

• maximum Hive Agent sessions reached (%d)
• agent session already exists: %s
• agent session not found: %s
• unknown method: %s
• list custom types in schema %q: %w

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/52a25db36bd4a662. Report an issue: GitHub.