Port 10015: Spark Thrift Server — The Hidden Doorway Into Big Data

What Range Is This Port In?

Port 10015 falls in the registered port range (1024-49151), which IANA manages for specific services. Any company or project can request registration for a port in this range. Registration doesn't mean the port is widely used—it just means someone filed paperwork saying "we want to use this for something."

What Uses Port 10015?

Port 10015 is the default Spark Thrift Server (STS) port for binary protocol mode. ^{1 2}

The Spark Thrift Server is Apache Spark's implementation of Hive's JDBC/ODBC server. It lets JDBC and ODBC clients connect to Apache Spark SQL and execute queries over a network. In big data environments (Hortonworks HDP, Cloudera, etc.), this is how applications talk to Spark: they send SQL queries to port 10015 and get results back. ³

The server also supports HTTP mode (which defaults to port 10001), but the binary protocol on 10015 is faster and more commonly used. ⁴

If you're in a Hadoop environment and need different ports, they're configurable. Spark 2 defaults to port 10016 instead of 10015. ⁵

How to Check What's Using Port 10015

On Linux/macOS:

# See what process is listening
lsof -i :10015

# Or use netstat/ss
netstat -tlnp | grep 10015
ss -tlnp | grep 10015

On Windows:

netstat -ano | findstr :10015

Then match the process ID to see what application owns that port.

With Spark specifically: If you run Spark Thrift Server, it will log which port it binds to during startup. Check the Spark logs if you're unsure.

Why This Port Matters

Port 10015 is invisible infrastructure. Most people will never see it. But in organizations running data warehouses or big data pipelines, thousands of queries flow through this port every day. It's the reason your BI tool can reach Spark. It's the reason your SQL queries don't just evaporate into the cluster.

Unassigned ports matter because they represent potential. This port could have been anything. Some engineer at Apache made the choice to default Spark Thrift Server to 10015, and now it's that. That's how standards form—not through committees alone, but through the decisions of people building things that work. The choice sticks because it works.