postgresql等待事件之wait_event為空解析
阿新 • • 發佈：2021-09-06
檢視某個語句的當前等待事件可以查詢pg_stat_activity表（類似於Oracle的v$session），如下所示：
select wait_event_type,wait_event,state,query,a.* from pg_stat_activity a where query like 'insert%';
wait_event_type|wait_event|state |query |datid |datname|pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event|state |backend_xid|backend_xmin|query |backend_type | ---------------+----------+------+---------------------------------------------------------------------+------+-------+-----+----------+--------+-------+------------------------------------------+------------+---------------+-----------+-------------------+-------------------+-------------------+-------------------+---------------+----------+------+-----------+------------+---------------------------------------------------------------------+--------------+| |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test|24870| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-97.sql>|172.24.32.48| | 53056|2021-09-06 21:34:52|2021-09-06 21:35:18|2021-09-06 21:35:18|2021-09-06 21:35:18| | |active|12755337 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend|
奇怪的是，雖然沒有任何阻塞，又是I/O密集型操作，居然只有state等於active，沒有等待事件。此時唯一的可能是在做計算密集型操作。可以通過pstack檢視PID檢視語句在做什麼，如下：
[zjh@lightdb1 pgsql13.2]$ pstack 24870 #0 0x000000000049553c in ginTraverseLock () #1 0x0000000000495cf9 in ginFindLeafPage () #2 0x0000000000498764 in ginInsertItemPointers () #3 0x000000000049e670 in ginEntryInsert () #4 0x000000000049a7c4 in ginInsertCleanup () #5 0x000000000049b1e8 in ginHeapTupleFastInsert () #6 0x000000000049ee98 in gininsert () #7 0x000000000061b8aa in ExecInsertIndexTuples () #8 0x00000000006445fa in ExecInsert () #9 0x0000000000645949 in ExecModifyTable () #10 0x000000000061c482 in standard_ExecutorRun () #11 0x00007f1da44e5f97 in pgss_ExecutorRun (queryDesc=0x1cac8f8, direction=ForwardScanDirection, count=0, execute_once=true) at pg_stat_statements.c:1045 #12 0x0000000000772bda in ProcessQuery () #13 0x0000000000772e14 in PortalRunMulti () #14 0x000000000077382d in PortalRun () #15 0x0000000000771412 in PostgresMain () #16 0x0000000000483069 in ServerLoop () #17 0x00000000006fe0b3 in PostmasterMain () #18 0x0000000000483cae in main ()
注：上述示例中，除了pg_stat_statements外掛外，pg沒有使用-g選項編譯，所以缺少原始檔資訊。
原來在更新gin索引。
wait_event_type|wait_event |state |query |datid |datname |pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event |state |backend_xid|backend_xmin|query |backend_type | ---------------+-------------+------+---------------------------------------------------------------------+------+--------+-----+----------+--------+-------+-------------------------------------------+------------+---------------+-----------+-------------------+-------------------+-------------------+-------------------+---------------+-------------+------+-----------+------------+---------------------------------------------------------------------+--------------+ IO |DataFileWrite|active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |25669| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-100.sql>|172.24.32.48| | 53166|2021-09-06 21:41:58|2021-09-06 21:42:20|2021-09-06 21:42:20|2021-09-06 21:42:20|IO |DataFileWrite|active|12755338 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| Client |ClientRead |idle |insert into big_search_doc_new_ic select * from big_search_doc_new_ic| 13580|postgres|24877| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-98.sql> |172.24.32.48| | 53062|2021-09-06 21:34:52| |2021-09-06 21:41:49|2021-09-06 21:41:49|Client |ClientRead |idle | | |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| | |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |24870| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-97.sql> |172.24.32.48| | 53056|2021-09-06 21:34:52|2021-09-06 21:35:18|2021-09-06 21:35:18|2021-09-06 21:35:18| | |active|12755337 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| wait_event_type|wait_event|state |query |datid |datname |pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event|state |backend_xid|backend_xmin|query |backend_type | ---------------+----------+------+---------------------------------------------------------------------+------+--------+-----+----------+--------+-------+-------------------------------------------+------------+---------------+-----------+-------------------+-------------------+-------------------+-------------------+---------------+----------+------+-----------+------------+---------------------------------------------------------------------+--------------+ LWLock |WALWrite |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |25669| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-100.sql>|172.24.32.48| | 53166|2021-09-06 21:41:58|2021-09-06 21:42:20|2021-09-06 21:42:20|2021-09-06 21:42:20|LWLock |WALWrite |active|12755338 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| Client |ClientRead|idle |insert into big_search_doc_new_ic select * from big_search_doc_new_ic| 13580|postgres|24877| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-98.sql> |172.24.32.48| | 53062|2021-09-06 21:34:52| |2021-09-06 21:41:49|2021-09-06 21:41:49|Client |ClientRead|idle | | |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| LWLock |WALWrite |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |24870| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-97.sql> |172.24.32.48| | 53056|2021-09-06 21:34:52|2021-09-06 21:35:18|2021-09-06 21:35:18|2021-09-06 21:35:18|LWLock |WALWrite |active|12755337 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| wait_event_type|wait_event |state |query |datid |datname |pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event |state |backend_xid|backend_xmin|query |backend_type | ---------------+------------+------+---------------------------------------------------------------------+------+--------+-----+----------+--------+-------+-------------------------------------------+------------+---------------+-----------+-------------------+-------------------+-------------------+-------------------+---------------+------------+------+-----------+------------+---------------------------------------------------------------------+--------------+ IO |DataFileRead|active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |25669| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-100.sql>|172.24.32.48| | 53166|2021-09-06 21:41:58|2021-09-06 21:42:20|2021-09-06 21:42:20|2021-09-06 21:42:20|IO |DataFileRead|active|12755338 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| Client |ClientRead |idle |insert into big_search_doc_new_ic select * from big_search_doc_new_ic| 13580|postgres|24877| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-98.sql> |172.24.32.48| | 53062|2021-09-06 21:34:52| |2021-09-06 21:41:49|2021-09-06 21:41:49|Client |ClientRead |idle | | |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| | |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |24870| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-97.sql> |172.24.32.48| | 53056|2021-09-06 21:34:52|2021-09-06 21:35:18|2021-09-06 21:35:18|2021-09-06 21:35:18| | |active|12755337 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| wait_event_type|wait_event |state |query |datid |datname |pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event |state |backend_xid|backend_xmin|query |backend_type | ---------------+--------------+------+---------------------------------------------------------------------+------+--------+-----+----------+--------+-------+-------------------------------------------+------------+---------------+-----------+-------------------+-------------------+-------------------+-------------------+---------------+--------------+------+-----------+------------+---------------------------------------------------------------------+--------------+ IO |DataFileExtend|active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |25669| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-100.sql>|172.24.32.48| | 53166|2021-09-06 21:41:58|2021-09-06 21:42:20|2021-09-06 21:42:20|2021-09-06 21:42:20|IO |DataFileExtend|active|12755338 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| Client |ClientRead |idle |insert into big_search_doc_new_ic select * from big_search_doc_new_ic| 13580|postgres|24877| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-98.sql> |172.24.32.48| | 53062|2021-09-06 21:34:52| |2021-09-06 21:41:49|2021-09-06 21:41:49|Client |ClientRead |idle | | |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| IO |DataFileRead |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |24870| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-97.sql> |172.24.32.48| | 53056|2021-09-06 21:34:52|2021-09-06 21:35:18|2021-09-06 21:35:18|2021-09-06 21:35:18|IO |DataFileRead |active|12755337 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| wait_event_type|wait_event |state |query |datid |datname |pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event |state |backend_xid|backend_xmin|query |backend_type | ---------------+-------------+------+---------------------------------------------------------------------+------+--------+-----+----------+--------+-------+-------------------------------------------+------------+---------------+-----------+-------------------+-------------------+-------------------+-------------------+---------------+-------------+------+-----------+------------+---------------------------------------------------------------------+--------------+ | |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |25669| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-100.sql>|172.24.32.48| | 53166|2021-09-06 21:41:58|2021-09-06 21:42:20|2021-09-06 21:42:20|2021-09-06 21:42:20| | |active|12755338 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| Client |ClientRead |idle |insert into big_search_doc_new_ic select * from big_search_doc_new_ic| 13580|postgres|24877| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-98.sql> |172.24.32.48| | 53062|2021-09-06 21:34:52| |2021-09-06 21:41:49|2021-09-06 21:41:49|Client |ClientRead |idle | | |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| LWLock |BufferContent|active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |24870| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-97.sql> |172.24.32.48| | 53056|2021-09-06 21:34:52|2021-09-06 21:35:18|2021-09-06 21:35:18|2021-09-06 21:35:18|LWLock |BufferContent|active|12755337 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| wait_event_type|wait_event |state |query |datid |datname |pid |leader_pid|usesysid|usename|application_name |client_addr |client_hostname|client_port|backend_start |xact_start |query_start |state_change |wait_event_type|wait_event |state |backend_xid|backend_xmin|query |backend_type | ---------------+------------+------+---------------------------------------------------------------------+------+--------+-----+----------+--------+-------+-------------------------------------------+------------+---------------+-----------+-------------------+-------------------+-------------------+-------------------+---------------+------------+------+-----------+------------+---------------------------------------------------------------------+--------------+ IO |WALInitWrite|active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |25669| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-100.sql>|172.24.32.48| | 53166|2021-09-06 21:41:58|2021-09-06 21:42:20|2021-09-06 21:42:20|2021-09-06 21:42:20|IO |WALInitWrite|active|12755338 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| Client |ClientRead |idle |insert into big_search_doc_new_ic select * from big_search_doc_new_ic| 13580|postgres|24877| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-98.sql> |172.24.32.48| | 53062|2021-09-06 21:34:52| |2021-09-06 21:41:49|2021-09-06 21:41:49|Client |ClientRead |idle | | |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend| LWLock |WALWrite |active|insert into big_search_doc_new_ic select * from big_search_doc_new_ic|107265|es_test |24870| | 10|zjh |DBeaver 21.1.5 - SQLEditor <Script-97.sql> |172.24.32.48| | 53056|2021-09-06 21:34:52|2021-09-06 21:35:18|2021-09-06 21:35:18|2021-09-06 21:35:18|LWLock |WALWrite |active|12755337 |12755337 |insert into big_search_doc_new_ic select * from big_search_doc_new_ic|client backend|
這個資訊是PG官方手冊和DBA不會告訴你的。
參考：
https://www.postgresql.org/docs/14/monitoring.html
LightDB Enterprise Postgres--金融級關係型資料庫,更快、更穩、更懂金融！