这是本节的多页打印视图。 .

Client 等待

PostgreSQL 等待应用、网络套接字、TLS/GSS 握手或复制客户端。

1: Client: ClientRead
2: Client: ClientWrite
3: Client: GssOpenServer
4: Client: LibpqwalreceiverConnect
5: Client: LibpqwalreceiverReceive
6: Client: SslOpenServer
7: Client: WaitForStandbyConfirmation
8: Client: WalSenderWaitForWal
9: Client: WalSenderWriteData

Client 颠倒了通常的怀疑方向：PostgreSQL 已准备好读取、写入或完成协议步骤，但远端或网络没有推进。连接池里的空闲连接很多时，大量 Client 等待往往完全正常。

状态与事务年龄决定严重度

ClientRead 加 state = 'idle' 属于预期。同一个事件若是 idle in transaction 且 xact_start 很老，就可能保留锁、快照和死元组。活动会话上的 ClientWrite 则说明服务器无法足够快地把结果交给消费者。

正常： 空闲池化连接等待下一条命令。
关注： 很老的 idle in transaction、活动状态的 ClientWrite、握手等待，或应用延迟同步上升。
紧急： 客户端停止消费结果、连接槽耗尽、打开的事务阻碍清理，或复制客户端反复断开。

值得先认出的事件

事件	第一个责任方
ClientRead	应用/连接池
ClientWrite	应用消费者或网络
GssOpenServer	认证/网络路径
SslOpenServer	TLS 握手路径
LibpqwalreceiverReceive	上游主库/网络
WalSenderWriteData	备库或复制客户端

常见误读

“大多数会话都在 ClientRead” 不是数据库瓶颈证据；还要看状态、事务年龄与连接池规模。
取消空闲客户端不能修复过大的连接池，只会让连接池重新连接。
即使数据库主机的网络看起来空闲，慢消费者仍会导致 ClientWrite。
带复制语义的 Client 等待仍位于协议边界，但运维责任方不同。

1 - Client: ClientRead

等待从客户端读取数据。

PostgreSQL 等待事件档案

类别Client 事件ClientRead 版本PG 13-18 证据2 个源码位置

官方描述译文

等待从客户端读取数据。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
✓	✓	✓	✓	✓	✓

触发机制

WAIT_EVENT_CLIENT_READ 位于 src/backend/libpq/be-secure.c:219，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event_names.txt:85。探针覆盖的操作是：等待从客户端读取数据。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 ClientRead；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'ClientRead'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'ClientRead'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 18.6 · src/backend/libpq/be-secure.c:219 — WAIT_EVENT_CLIENT_READ
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:85 — CLIENT_READ

GUC: [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:active_backends]

2 - Client: ClientWrite

等待向客户端写入数据。

PostgreSQL 等待事件档案

类别Client 事件ClientWrite 版本PG 13-18 证据2 个源码位置

官方描述译文

等待向客户端写入数据。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
✓	✓	✓	✓	✓	✓

触发机制

WAIT_EVENT_CLIENT_WRITE 位于 src/backend/libpq/be-secure.c:344，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event_names.txt:86。探针覆盖的操作是：等待向客户端写入数据。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 ClientWrite；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'ClientWrite'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'ClientWrite'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 18.6 · src/backend/libpq/be-secure.c:344 — WAIT_EVENT_CLIENT_WRITE
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:86 — CLIENT_WRITE

GUC: [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:active_backends]

3 - Client: GssOpenServer

建立 GSSAPI 会话时，等待从客户端读取数据。

PostgreSQL 等待事件档案

类别Client 事件GssOpenServer 版本PG 17-18 证据4 个源码位置

官方描述译文

建立 GSSAPI 会话时，等待从客户端读取数据。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
—	—	—	—	✓	✓

历史名称：Client/GSSOpenServer (PG 13-16)

触发机制

WAIT_EVENT_GSS_OPEN_SERVER 位于 src/backend/libpq/be-secure-gssapi.c:461，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event.c:277。探针覆盖的操作是：建立 GSSAPI 会话时，等待从客户端读取数据。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 GssOpenServer；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'GssOpenServer'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'GssOpenServer'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 16.15 · src/backend/libpq/be-secure-gssapi.c:461 — WAIT_EVENT_GSS_OPEN_SERVER
PostgreSQL 16.15 · src/backend/utils/activity/wait_event.c:277 — GSSOpenServer
PostgreSQL 18.6 · src/backend/libpq/be-secure-gssapi.c:462 — WAIT_EVENT_GSS_OPEN_SERVER
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:87 — GSS_OPEN_SERVER

GUC: [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:active_backends]

4 - Client: LibpqwalreceiverConnect

在 WAL receiver 中等待与远程服务器建立连接。

PostgreSQL 等待事件档案

类别Client 事件LibpqwalreceiverConnect 版本PG 17-18 证据4 个源码位置

官方描述译文

在 WAL receiver 中等待与远程服务器建立连接。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
—	—	—	—	✓	✓

历史名称：Client/LibPQWalReceiverConnect (PG 13-16)

触发机制

WAIT_EVENT_LIBPQWALRECEIVER_CONNECT 位于 src/backend/replication/libpqwalreceiver/libpqwalreceiver.c:231，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event.c:280。探针覆盖的操作是：在 WAL receiver 中等待与远程服务器建立连接。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 LibpqwalreceiverConnect；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'LibpqwalreceiverConnect'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'LibpqwalreceiverConnect'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 16.15 · src/backend/replication/libpqwalreceiver/libpqwalreceiver.c:231 — WAIT_EVENT_LIBPQWALRECEIVER_CONNECT
PostgreSQL 16.15 · src/backend/utils/activity/wait_event.c:280 — LibPQWalReceiverConnect
PostgreSQL 18.6 · src/backend/replication/libpqwalreceiver/libpqwalreceiver.c:228 — WAIT_EVENT_LIBPQWALRECEIVER_CONNECT
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:88 — LIBPQWALRECEIVER_CONNECT

GUC: [guc:wal_buffers] · [guc:synchronous_commit] · [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:wal_bytes] · [metric:wal_write_time] · [metric:active_backends]

5 - Client: LibpqwalreceiverReceive

在 WAL receiver 中等待从远程服务器接收数据。

PostgreSQL 等待事件档案

类别Client 事件LibpqwalreceiverReceive 版本PG 17-18 证据4 个源码位置

官方描述译文

在 WAL receiver 中等待从远程服务器接收数据。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
—	—	—	—	✓	✓

历史名称：Client/LibPQWalReceiverReceive (PG 13-16)

触发机制

WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE 位于 src/backend/replication/libpqwalreceiver/libpqwalreceiver.c:876，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event.c:283。探针覆盖的操作是：在 WAL receiver 中等待从远程服务器接收数据。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 LibpqwalreceiverReceive；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'LibpqwalreceiverReceive'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'LibpqwalreceiverReceive'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 16.15 · src/backend/replication/libpqwalreceiver/libpqwalreceiver.c:876 — WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE
PostgreSQL 16.15 · src/backend/utils/activity/wait_event.c:283 — LibPQWalReceiverReceive
PostgreSQL 18.6 · src/backend/replication/libpqwalreceiver/libpqwalreceiver.c:258 — WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:89 — LIBPQWALRECEIVER_RECEIVE

GUC: [guc:wal_buffers] · [guc:synchronous_commit] · [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:wal_bytes] · [metric:wal_write_time] · [metric:active_backends]

6 - Client: SslOpenServer

尝试建立连接时等待 SSL。

PostgreSQL 等待事件档案

类别Client 事件SslOpenServer 版本PG 17-18 证据4 个源码位置

官方描述译文

尝试建立连接时等待 SSL。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
—	—	—	—	✓	✓

历史名称：Client/SSLOpenServer (PG 13-16)

触发机制

WAIT_EVENT_SSL_OPEN_SERVER 位于 src/backend/libpq/be-secure-openssl.c:508，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event.c:286。探针覆盖的操作是：尝试建立连接时等待 SSL。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 SslOpenServer；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'SslOpenServer'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'SslOpenServer'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 16.15 · src/backend/libpq/be-secure-openssl.c:508 — WAIT_EVENT_SSL_OPEN_SERVER
PostgreSQL 16.15 · src/backend/utils/activity/wait_event.c:286 — SSLOpenServer
PostgreSQL 18.6 · src/backend/libpq/be-secure-openssl.c:526 — WAIT_EVENT_SSL_OPEN_SERVER
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:90 — SSL_OPEN_SERVER

GUC: [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:active_backends]

7 - Client: WaitForStandbyConfirmation

等待物理备库接收并刷写 WAL。

PostgreSQL 等待事件档案

类别Client 事件WaitForStandbyConfirmation 版本PG 17-18 证据2 个源码位置

官方描述译文

等待物理备库接收并刷写 WAL。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
—	—	—	—	✓	✓

触发机制

WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION 位于 src/backend/replication/slot.c:3083，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event_names.txt:91。探针覆盖的操作是：等待物理备库接收并刷写 WAL。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 WaitForStandbyConfirmation；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'WaitForStandbyConfirmation'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'WaitForStandbyConfirmation'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 18.6 · src/backend/replication/slot.c:3083 — WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:91 — WAIT_FOR_STANDBY_CONFIRMATION

GUC: [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:active_backends]

8 - Client: WalSenderWaitForWal

在 WAL sender 进程中等待 WAL 完成刷写。

PostgreSQL 等待事件档案

类别Client 事件WalSenderWaitForWal 版本PG 17-18 证据4 个源码位置

官方描述译文

在 WAL sender 进程中等待 WAL 完成刷写。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
—	—	—	—	✓	✓

历史名称：Client/WalSenderWaitForWAL (PG 13-16)

触发机制

WAIT_EVENT_WAL_SENDER_WAIT_WAL 位于 src/backend/replication/walsender.c:1714，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event.c:289。探针覆盖的操作是：在 WAL sender 进程中等待 WAL 完成刷写。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 WalSenderWaitForWal；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'WalSenderWaitForWal'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'WalSenderWaitForWal'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 16.15 · src/backend/replication/walsender.c:1714 — WAIT_EVENT_WAL_SENDER_WAIT_WAL
PostgreSQL 16.15 · src/backend/utils/activity/wait_event.c:289 — WalSenderWaitForWAL
PostgreSQL 18.6 · src/backend/replication/walsender.c:1813 — WAIT_EVENT_WAL_SENDER_WAIT_FOR_WAL
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:92 — WAL_SENDER_WAIT_FOR_WAL

GUC: [guc:wal_buffers] · [guc:synchronous_commit] · [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:wal_bytes] · [metric:wal_write_time] · [metric:active_backends]

9 - Client: WalSenderWriteData

在 WAL sender 进程中处理 WAL receiver 的回复时，等待发生任何活动。

PostgreSQL 等待事件档案

类别Client 事件WalSenderWriteData 版本PG 13-18 证据2 个源码位置

官方描述译文

在 WAL sender 进程中处理 WAL receiver 的回复时，等待发生任何活动。

PG 13	PG 14	PG 15	PG 16	PG 17	PG 18
✓	✓	✓	✓	✓	✓

触发机制

WAIT_EVENT_WAL_SENDER_WRITE_DATA 位于 src/backend/replication/walsender.c:1653，是经 grep 核验的报告路径。公共身份/资源映射位于 src/backend/utils/activity/wait_event_names.txt:93。探针覆盖的操作是：在 WAL sender 进程中处理 WAL receiver 的回复时，等待发生任何活动。前端协议路径在套接字、TLS/GSS 或复制客户端操作即将阻塞前报告 WalSenderWriteData；PostgreSQL 正在等待远端或网络推进。

正常还是麻烦？

正常: 空闲状态的 ClientRead 通常只是连接池存量。
需要调查: 活动写入、握手、很老的 idle in transaction、连接耗尽或复制客户端停滞时需要调查。

诊断 SQL

SELECT pid, backend_type, usename, datname, application_name,
       state, now() - query_start AS query_age,
       now() - xact_start AS xact_age,
       wait_event_type, wait_event,
       pg_blocking_pids(pid) AS blocking_pids,
       left(query, 160) AS query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
  AND wait_event = 'WalSenderWriteData'
ORDER BY query_age DESC NULLS LAST;

SELECT wait_event, count(*) AS waiting_sessions,
       count(*) FILTER (WHERE state = 'active') AS active_waiters,
       max(now() - query_start) AS oldest_query
FROM pg_stat_activity
WHERE wait_event_type = 'Client'
GROUP BY wait_event
ORDER BY waiting_sessions DESC, wait_event;

SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,
       d.datname, n.nspname, c.relname,
       l.page, l.tuple, l.virtualxid, l.transactionid,
       l.classid, l.objid, l.objsubid
FROM pg_stat_activity AS a
LEFT JOIN pg_locks AS l ON l.pid = a.pid
LEFT JOIN pg_database AS d ON d.oid = l.database
LEFT JOIN pg_class AS c
  ON c.oid = l.relation
 AND l.database = (
       SELECT oid FROM pg_database WHERE datname = current_database()
     )
LEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace
WHERE a.wait_event_type = 'Client'
  AND a.wait_event = 'WalSenderWriteData'
ORDER BY a.pid, l.granted, l.locktype, l.mode;

处置建议

先看 state 与事务年龄，再决定它是否算负载。
关联负责的应用、连接池与网络路径。
修复消费者背压或连接池策略，不要反复终止连接。

源码证据

PostgreSQL 18.6 · src/backend/replication/walsender.c:1653 — WAIT_EVENT_WAL_SENDER_WRITE_DATA
PostgreSQL 18.6 · src/backend/utils/activity/wait_event_names.txt:93 — WAL_SENDER_WRITE_DATA

GUC: [guc:wal_buffers] · [guc:synchronous_commit] · [guc:max_connections] · [guc:idle_in_transaction_session_timeout]
指标: [metric:waiting_sessions] · [metric:wait_event_share] · [metric:wal_bytes] · [metric:wal_write_time] · [metric:active_backends]

Client 等待

状态与事务年龄决定严重度

值得先认出的事件

常见误读

1 - Client: ClientRead

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

2 - Client: ClientWrite

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

3 - Client: GssOpenServer

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

4 - Client: LibpqwalreceiverConnect

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

5 - Client: LibpqwalreceiverReceive

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

6 - Client: SslOpenServer

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

7 - Client: WaitForStandbyConfirmation

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

8 - Client: WalSenderWaitForWal

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号

9 - Client: WalSenderWriteData

官方描述译文

触发机制

正常还是麻烦？

诊断 SQL

处置建议

源码证据

关联控制项与信号