Account Activity Tracking#

Dify tracks when accounts were last active via the last_active_at column on the Account model. The system throttles DB writes using Redis and surfaces the value in the UI as a human-readable relative time string.

Data Model#

Account.last_active_at is a non-nullable DateTime column initialized by the database clock via server_default=func.current_timestamp() 1. Unlike created_at/updated_at on newer models that use DefaultFieldsMixin (which also set a Python-side default via naive_utc_now()), last_active_at has no Python-side default — its initial value always comes from the DB clock.

Clock consistency note: Because the initial write uses the DB clock and subsequent updates use the Python application clock (naive_utc_now()), there is a potential off-by-milliseconds discrepancy between the first value and later updates. See the Timestamp Management knowledge article for the broader pattern.

Update Flow#

last_active_at is refreshed on every authenticated request via AccountService.load_user(), which calls _refresh_account_last_active() before returning. Two guards prevent excessive DB writes:

Guard 1 — In-memory staleness check#

Before touching Redis or the database, the method computes refresh_before = now - 10 minutes and bails out if account.last_active_at >= refresh_before 2. This short-circuits the Redis round-trip on most requests.

Guard 2 — Redis distributed lock (10-minute TTL)#

If the in-memory check passes, _should_refresh_account_last_active() issues a Redis SET … EX … NX on key account_last_active_refresh:{account_id} with a 10-minute expiry 3. The constants are defined at module level:

• ACCOUNT_LAST_ACTIVE_REFRESH_PREFIX = "account_last_active_refresh:" 4
• ACCOUNT_LAST_ACTIVE_REFRESH_INTERVAL = timedelta(minutes=10) 5

SET NX is atomic — only one worker across all processes can win the lock and perform the DB write. The method is decorated with @redis_fallback(default_return=True), so if Redis is unavailable the update proceeds anyway 3.

DB write#

When both guards pass, a targeted UPDATE is issued — not a full ORM flush 6:

UPDATE accounts
SET last_active_at = <now>, updated_at = CURRENT_TIMESTAMP
WHERE id = :id AND last_active_at < :refresh_before

The WHERE last_active_at < refresh_before predicate makes the write idempotent against concurrent races: whichever worker wins the Redis lock will perform the update; any lagging worker whose Redis key expired between the check and the write will be stopped by this predicate.

Frontend Display#

The useFormatTimeFromNow React hook formats last_active_at as a locale-aware relative string (e.g., "3 minutes ago") 7. It uses the dayjs relativeTime plugin and resolves the locale from useLocale() via a localeMap lookup, with 'en' as fallback 8. The hook bundles locale data for 20+ languages 9.

Key Files#