alibaba/arthas · error · SessionNotFoundException

Failed to create temporary session

Error message

Failed to create temporary session

What it means

Thrown as SessionNotFoundException by getCurrentSession when a one-time call was permitted (oneTimeIsAllowed=true) but sessionManager.createSession() returned null. This indicates the session manager refused to allocate a session — typically because a configured limit (max sessions) was reached or the manager is shut down.

Source

Thrown at core/src/main/java/com/taobao/arthas/core/command/CommandExecutorImpl.java:62

    private final SessionManager sessionManager;
    private final JobController jobController;
    private final InternalCommandManager commandManager;

    public CommandExecutorImpl(SessionManager sessionManager) {
        this.sessionManager = sessionManager;
        this.commandManager = sessionManager.getCommandManager();
        this.jobController = sessionManager.getJobController();
    }

    public Session getCurrentSession(String sessionId, boolean oneTimeIsAllowed) {
        if (sessionId == null || sessionId.trim().isEmpty()) {
            if (!oneTimeIsAllowed) {
                throw new SessionNotFoundException("SessionId is required for this operation");
            }

            Session session = sessionManager.createSession();
            if (session == null) {
                throw new SessionNotFoundException("Failed to create temporary session");
            }
            session.put(ONETIME_SESSION_KEY, new Object());
            logger.debug("Created one-time session {}", session.getSessionId());
            return session;
        } else {
            Session session = sessionManager.getSession(sessionId);
            if (session == null) {
                throw new SessionNotFoundException("Session not found: " + sessionId);
            }
            sessionManager.updateAccessTime(session);
            logger.debug("Using existing session {}", sessionId);
            return session;
        }
    }

    /**
     * 内部同步执行方法，统一处理认证和session管理
     * 

View on GitHub (pinned to 21cf2e9ba5)

Solutions

1. Increase the max-sessions limit in Arthas options.
2. Close/expire idle sessions so createSession can succeed (check sessionManager for active sessions).
3. Verify Arthas is not shutting down at call time.
4. Switch to passing an explicit sessionId rather than relying on one-time creation.

Example fix

// before
// relies on implicit one-time session that fails under load
Session s = executor.getCurrentSession(null, true);

// after
// reuse a long-lived session
Session s = sessionManager.getSession(mySid);
if (s == null) { s = sessionManager.createSession(); mySid = s.getSessionId(); }

int active = sessionManager.activeSessionCount(); // pseudo
if (active >= maxLimit) { /* expire idle sessions or raise the cap */ }

try {
    Session s = executor.getCurrentSession(null, true);
} catch (SessionNotFoundException e) {
    // expire/close an idle session, then retry; or reuse an existing session id
}

When it happens

Trigger: Call getCurrentSession(null/blank, true) where sessionManager.createSession() returns null. Happens when the max-session cap is hit, the manager is stopped, or resource limits prevent new session allocation.

Common situations: Too many concurrent sessions exhausting the configured maximum; leaked sessions never expiring; calling after Arthas shutdown has begun; memory/thread pressure causing session creation to fail.

Related errors

• SessionId is required for this operation
• Session not found: {sessionId}
• Error! command not permitted, try to use 'auth' command to a
• 'sessionId' is required
• session not found: {}

AI-assisted analysis of alibaba/arthas@21cf2e9ba5 (2026-08-14). Data as JSON: /api/errors/400d226c97385c67. Report an issue: GitHub.