@Rocky How long does starrocks close idle, dead, or orphaned connections? What would the timeout be?

StarRocks provides several mechanisms and timeouts to manage idle, dead, or orphaned connections. The behavior depends on whether the connection is simply sitting idle or if the underlying TCP connection has been lost. 1. Idle Connections (

wait_timeout

) For connections that are alive but inactive (no queries being sent), StarRocks uses the

wait_timeout

system variable. * Default Timeout: 28800 seconds (8 hours). * Behavior: If a client does not interact with the StarRocks server for this duration, StarRocks will actively close the connection. * How to Change: You can adjust this globally or for a specific session:

sql
    -- Set globally for all new connections
    SET GLOBAL wait_timeout = 3600; -- 1 hour

    -- Set for the current session
    SET wait_timeout = 600; -- 10 minutes

2. Dead or Orphaned Connections If a client "disappears" (e.g., the client process crashes or a network cable is pulled) without closing the connection properly, StarRocks relies on the following: * TCP Keep-Alive: By default, StarRocks enables TCP Keep-Alive for MySQL connections to detect dead peers. * FE Configuration:

mysql_service_nio_enable_keep_alive

(Default:

true

). * Automatic Cleanup on Disconnect: If StarRocks detects that the TCP connection has been closed (EOF on read), it will clean up the session. * FE Configuration:

mysql_service_kill_after_disconnect

(Default:

true

). When enabled, StarRocks immediately kills any running queries associated with that connection and performs cleanup. 3. Query Timeouts (

query_timeout

) If a connection is "stuck" because a query is running for too long, the

query_timeout

variable applies. * Default Timeout: 300 seconds (5 minutes). * Behavior: If a query exceeds this limit, StarRocks will terminate the query, though the connection itself remains open for the next request (unless

wait_timeout

is also reached). Summary Table Connection State | Governing Variable / Config | Default Value Idle (Inactive) |

wait_timeout

| 28800s (8 hrs) Running Query |

query_timeout

| 300s (5 mins) TCP Disconnected |

mysql_service_kill_after_disconnect

|

true

(Immediate) Orphaned (Dead Peer) | TCP Keep-Alive | OS Level /

mysql_service_nio_enable_keep_alive

Tip: You can manually inspect and remove connections using: *

SHOW PROCESSLIST;

— To see all active connections and their idle time (the

Time

column). *

KILL [connection_id];

— To manually terminate a specific connection. References • administration/management/FE_configuration.md • faq/Sql_faq.md