Hi all,
We are encountering an intermittent issue where our Windows-based
application hangs indefinitely during SQLConnect when connecting to a
PostgreSQL server via ODBC.
Environment
- PostgreSQL version: 15.0.15.25315
- ODBC driver: psqlODBC 16.00.0007
- Connection type: ODBC using certificate-based authentication
- Deployment: Application and PostgreSQL server both run on the same
machine (localhost)
Application Behavior
- The application maintains:
- Some long-lived persistent connections
- A few short-lived connections (3–4) that are opened/closed
periodically
- Connection pooling is enabled (we also tested with pooling disabled
and reduced timeouts—no change)
Configuration
- Connection timeout is explicitly set before calling SQLConnect
- TCP keepalive parameters are configured
- Both settings are visible in PostgreSQL ODBC trace logs
Issue Description
On a subset of systems, intermittently (roughly once a week, sometimes more
frequently), the SQLConnect call:
- Hangs indefinitely
- Does not return or timeout
Observations / Troubleshooting
- Initially suspected Microsoft Defender or network filtering:
- Added PostgreSQL data directory to exclusions → no improvement
- No network filtering/firewall issues observed
- Adjusted connection pooling and timeout values → no impact
Call Stack During Hang
mswsock!WSPStartup
mswsock!WSPStartup
ws2_32!select
libpq!PQsocketPoll
libpq!PQsocketPoll
libpq!PQgetResult
psqlodbc35w!Ordinal94
psqlodbc35w!Ordinal94
psqlodbc35w!Ordinal94
psqlodbc35w!SQLConnectW
odbc32!SQLConnectW
odbc32!ODBCSetTryWaitValue
comsvcs!DispManGetContext
comsvcs!DispManGetContext
odbc32!SQLDriverConnectW
odbc32!SQLDriverConnectW
odbc32!SQLFreeStmt
odbc32!SQLConnectW
odbc32!SQLConnect
>From the stack, it appears the hang occurs in:
- libpq!PQsocketPoll / PQgetResult, which eventually blocks in
- ws2_32!select
This suggests the thread is waiting on a socket event during connection
establishment (possibly SSL/certificate handshake or server response).
Questions
- Has anyone experienced similar behavior with PostgreSQL 15 and
psqlODBC on Windows?
- Are there known issues where SQLConnect can block indefinitely despite
configured timeouts?
- Could this be related to libpq socket polling behavior or SSL/cert
authentication edge cases?
Any insights or suggestions for further diagnostics would be greatly
appreciated.
Thanks in advance.
