Client/WalSenderWriteData

各版本描述

相邻版本里类型、名称与英文描述都相同的合并成一段，旧的在前。中文取自图谱或本站手册译文，没有译文的只给英文原文。

1. 10–20

   Client/WalSenderWriteData

   在 WAL 发送进程中处理 WAL 接收进程的回复时，等待任何活动。

   Waiting for any activity when processing replies from WAL receiver in WAL sender process.

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。

WAIT_EVENT_WAL_SENDER_WRITE_DATA at src/backend/replication/walsender.c:1653 is the grep-verified reporting path. The public identity/resource is mapped at src/backend/utils/activity/wait_event_names.txt:93. The instrumented operation is: Waiting for any activity when processing replies from WAL receiver in WAL sender process. The frontend protocol path reports WalSenderWriteData immediately before a socket, TLS/GSS, or replication-client operation blocks. PostgreSQL is waiting for the remote side or network to progress.

诊断 SQL

直接在 psql 里跑；标注的是语句里用到的视图与列所要求的最低版本。

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;

处置步骤

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

相关参数与指标

wal_bufferssynchronous_commitmax_connectionsidle_in_transaction_session_timeout waiting_sessionswait_event_sharewal_byteswal_write_timeactive_backends

源码证据

图谱在各版本源码树里核对到的位置，新的在前。「触发点」是真正上报等待事件的调用处，「目录定义」只说明这个名字在枚举里存在。

演化历史

相邻两个大版本之间的差异，新的在前。版本号链到该版的变动清单。

1. PostgreSQL 10 ← 9.6 新增此事件

   该版起出现

   在 WAL 发送进程中处理 WAL 接收进程的回复时，等待任何活动。

同类事件