fe_threads

fe_threads provides information about the threads running on each FE node.

The following fields are provided in fe_threads:

Field	Description
FE_ADDRESS	Address of the FE node (format: host:port).
THREAD_ID	Java thread ID.
THREAD_NAME	Name of the thread.
THREAD_STATE	State of the thread. Possible values: NEW, RUNNABLE, BLOCKED, WAITING, TIMED_WAITING, TERMINATED.
IS_DAEMON	Indicates whether the thread is a daemon thread (true) or not (false).
PRIORITY	Thread priority (typically 1-10).
CPU_TIME_MS	CPU time consumed by the thread in milliseconds. Returns -1 if CPU time measurement is not supported.
USER_TIME_MS	User time consumed by the thread in milliseconds. Returns -1 if user time measurement is not supported.

Usage Examples

Query all threads

SELECT * FROM information_schema.fe_threads;

Query threads by state

SELECT thread_id, thread_name, thread_state 
FROM information_schema.fe_threads 
WHERE thread_state = 'RUNNABLE';

Count threads by state

SELECT thread_state, COUNT(*) AS count 
FROM information_schema.fe_threads 
GROUP BY thread_state 
ORDER BY count DESC;

Find daemon threads

SELECT thread_id, thread_name, thread_state 
FROM information_schema.fe_threads 
WHERE is_daemon = true;

Find threads with highest CPU usage

SELECT thread_id, thread_name, cpu_time_ms 
FROM information_schema.fe_threads 
WHERE cpu_time_ms >= 0 
ORDER BY cpu_time_ms DESC 
LIMIT 10;

Search for specific thread names

SELECT thread_id, thread_name, thread_state 
FROM information_schema.fe_threads 
WHERE thread_name LIKE '%main%' 
   OR thread_name LIKE '%GC%';

Count threads by daemon status

SELECT is_daemon, COUNT(*) AS count 
FROM information_schema.fe_threads 
GROUP BY is_daemon;

Get thread statistics

SELECT 
    COUNT(*) AS total_threads,
    COUNT(DISTINCT thread_state) AS distinct_states,
    COUNT(DISTINCT thread_name) AS distinct_names,
    SUM(CASE WHEN is_daemon THEN 1 ELSE 0 END) AS daemon_count,
    SUM(CASE WHEN NOT is_daemon THEN 1 ELSE 0 END) AS non_daemon_count
FROM information_schema.fe_threads;