Postgres JDBC客户端在从套接字读取时卡住

Question

我有一个PostGIS数据库和一个基于HikariCP构建的客户端，用于从数据库中读取数据。我的客户可以在一些机器上毫无问题地读取数据。然而，在其他一些机器上，客户机被卡住，不能读取任何数据，抛出套接字超时异常。

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

在客户端在数据库端抛出SocketTimeoutExc的之前，我监视了pg_stat_activity表。上面查询的相应行有wait_event_type=客户端和wait_event=客户端写入。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）
• 光CP：3.1.0
• 邮政服务器：10.3
• 后地理信息系统服务器：2.4.4

如果我没有通过 jdbc 连接字符串设置 socketTimeout，那么连接将永远卡住。一旦连接达到其最长html" target="_blank">生命周期，它将被丢弃并再次连接。但是，它仍然无法读取数据。当我设置套接字超时时，会抛出异常。

更新如果未设置< code>socketTimeout，则< code>pg_stat_activity表中会有一行包含以下值的连接:< code > state = idle in transaction 、< code > wait _ event _ type = Client 和< code > wait _ event = Client read 。

我猜是某种网络设置阻止了客户端服务器的读取。我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并导致丢包。将其更改为1500解决了问题。