Postgres JDBC 客户端在从套接字读取时卡住了

Question

我有一个 PostGIS 数据库和一个构建在 HikariCP 之上的客户端，用于从数据库中读取数据。我的客户端可以毫无问题地读取数据 在某些机器上 。但是，在其他一些机器上，客户端会卡住并且无法读取任何抛出套接字超时异常的数据。

MyClass:120 - Failed to execute HikariProxyPreparedStatement@2091541230 wrapping <my-query>.
org.postgresql.util.PSQLException: An I/O error occurred while sending to the backend.
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:332)
    at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:441)
    at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:365)
    at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:155)
    at org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:118)
    at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52)
    at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java)
    ...
Caused by: java.net.SocketTimeoutException: Read timed out
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
    at java.net.SocketInputStream.read(SocketInputStream.java:171)
    at java.net.SocketInputStream.read(SocketInputStream.java:141)
    at org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:140)
    at org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:109)
    at org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:67)
    at org.postgresql.core.PGStream.receiveChar(PGStream.java:293)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1947)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:306)
    ... 32 more

ProxyConnection:161 - HikariPool-1 - Connection org.postgresql.jdbc.PgConnection@1aafd32f marked as broken because of SQLSTATE(08006), ErrorCode(0)
org.postgresql.util.PSQLException: An I/O error occurred while sending to the backend.
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:332)
    at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:441)
    at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:365)
    at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:155)
    at org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:118)
    at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52)
    at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java)
    ...
Caused by: java.net.SocketTimeoutException: Read timed out
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
    at java.net.SocketInputStream.read(SocketInputStream.java:171)
    at java.net.SocketInputStream.read(SocketInputStream.java:141)
    at org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:140)
    at org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:109)
    at org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:67)
    at org.postgresql.core.PGStream.receiveChar(PGStream.java:293)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1947)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:306)
    ... 31 more

客户端在数据库端抛出SocketTimeoutException之前，我监控了pg_stat_activitytable。上面查询的对应行有 wait_event_type=Client 和 wait_event=ClientWrite。此外，数据库服务器记录了指示连接丢失的消息。

LOG:  unexpected EOF on client connection with an open transaction
LOG:  could not send data to client: Connection timed out
FATAL:  connection to client lost

版本

PostGIS-jdbc: 2.2.1 (postgresql jdbc: 9.4.1208.jre7)
HikariCP: 3.1.0
Postgres 服务器：10.3
PostGIS 服务器：2.4.4

如果我不通过 jdbc 连接字符串设置 socketTimeout，那么连接将永远卡住。一旦连接达到其最大生命周期，它将被断开并再次连接。但是，它仍然无法读取数据。当我设置 socketTimeout 时，会抛出异常。

更新如果未设置 socketTimeout，则 pg_stat_activity table 将有一行具有以下值的连接：state=idle in transaction、wait_event_type=Client 和 wait_event=ClientRead .

我的猜测是某种网络设置阻止了客户端从服务器读取。我该如何进一步调试并找到根本原因？

Answer 1

我们发现这是由数据库服务器的 MTU 设置引起的。 MTU 默认设置为 9000，导致丢包。将其更改为 1500 解决了问题。

Postgres JDBC 客户端在从套接字读取时卡住了

Postgres JDBC client getting stuck at reading from socket

postgresql

postgis

jdbc

hikaricp