BUG #15054: intermittent error: An I/O error occured while sending to the backend.

The following bug has been logged on the website:

Bug reference: 15054
Logged by: Ming Chen
Email address: czmy(at)hotmail(dot)com
PostgreSQL version: 9.3.20
Operating system: Redhat Enterprise 6
Description:

We experienced intermittent error about "An I/O error occured while sending
to the backend" recently.

We also observed the following facts.
1. On 9.3.17, we starts to have this issue after 6000 calls (each call is a
couple of SQL queries). The chance of error is less than 0.5%.
2. After we upgrade to 9.3.18 or 9.3.20, the error happens right away (We
don't have to wait for the first 6000 calls). The chance of error is about
1%.
3. Since the error appears right away, which is less than 2 mins after
restarting Postgresql, I don't feel it is related to socket timeout (Note
that this is a RedHat system).
4. The error sometimes happened in a select statement, sometimes in an
update. I don't feel it is related the statements that we are executing.

The error detail is as follows,

Exception executing SQL "INSERT INTO .........." for task
"PreparedStatementCallback". SQLState is "08006".
org.postgresql.util.PSQLException: An I/O error occured while sending to the
backend.
at
org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:283)
at
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:500)
at
org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:388)
at
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:381)
at
org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:172)
at
org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:172)
at
org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:172).