msphpsql: Linux: TCP error 0x2714 after Apache reload

PHP Driver version or file name

5.9.0

SQL Server version

Microsoft SQL Server 2019 (RTM-CU8-GDR) (KB4583459) - 15.0.4083.2 (X64)

Client operating system

RHEL 7.8 Kernel: Linux 3.10.0-1127.18.2.el7.x86_64 x86_64

PHP version

7.4.16 NTS (7.4.16-1.el7.remi)

Microsoft ODBC Driver version

Microsoft ODBC Driver for SQL Server 17.7.1.1 (msodbcsql17.x86_64 17.7.1.1-1) unixODBC 2.3.7 (unixODBC.x86_64 2.3.7-1.rh)

Table schema

N/A

Problem description

Reloading Apache during a long-running query causes the next query to be executed after child processes come back to generate the following error: SQLSTATE[08S01]: [Microsoft][ODBC Driver 17 for SQL Server]TCP Provider: Error code 0x2714

Occasionally this error occurs instead: SQLSTATE[08S01]: [Microsoft][ODBC Driver 17 for SQL Server]Communication link failure

Expected behavior and actual behavior

The next query should succeed.

Repro code or steps to reproduce

Create a script with the following:

$pdo = new PDO( 'sqlsrv:Server=server; LoginTimeout=15; MultipleActiveResultSets=false', '', '', [ PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION ] );

$pdo->query( "WAITFOR DELAY '00:00:05'" );

var_dump( $pdo->query( 'SELECT 1 AS Row1' )->fetchAll( PDO::FETCH_ASSOC ) );

Save the script in a location that can be served up by Apache (httpd24-httpd.x86_64 2.4.34-18.el7 in my case) and executed by PHP. For example: http://localhost/test.php

Continually refresh the page after after it has been served (will take a minimum of 5 seconds due to the WAITFOR).

Reload the Apache service. My RHEL installation required /bin/systemctl reload httpd24-httpd.service.

Once child processes are back, reloading the page (executing the script) will generate the error stated above.

The issue only seems to happen when using PDO_SQLSRV and not any other PDO driver. For example, I’ve tried the following and was unable to reproduce:

• new PDO( 'odbc:server', '', '' ) - using PDO_ODBC instead
• new PDO( 'dblib:server', '', '' ) - using FreeTDS

Tried the following but the issue still occurred:

• Disabling pooling
• Restarting Apache service instead of reloading (/bin/systemctl restart httpd24-httpd.service)
• ConnectRetryCount > 1 in the DSN (I believe this is Windows only though so no surprise there)

odbcinst -j output:

unixODBC 2.3.7
DRIVERS............: /etc/odbcinst.ini
SYSTEM DATA SOURCES: /etc/odbc.ini
FILE DATA SOURCES..: /etc/ODBCDataSources
USER DATA SOURCES..: /home/user/.odbc.ini
SQLULEN Size.......: 8
SQLLEN Size........: 8
SQLSETPOSIROW Size.: 8

Relevant section of odbcinst.ini:

[ODBC Driver 17 for SQL Server]
Description=Microsoft ODBC Driver 17 for SQL Server
Driver=/opt/microsoft/msodbcsql17/lib64/libmsodbcsql-17.7.so.1.1
UsageCount=1
CPTimeout=120

Let me know if anything else is needed.