Debugging "Killed" Errors in osm2pgrouting with Docker: A Guide to Road Network Topology Creation
Creating a road network topology from OpenStreetMap data using osm2pgrouting is a common task for transportation planning and analysis. However, you might encounter the frustrating "Killed" error during the process, even after increasing the swap file size. This article will explore the reasons behind this error and offer solutions to overcome it.
The Scenario:
Let's say you're using a Docker container to run osm2pgrouting on your OpenStreetMap data. You increase the swap file size to address potential memory issues, but you still get the "Killed" error message.
Here's the code snippet that might be causing the issue:
docker run -it -v /path/to/osm/data:/data -v /path/to/pgrouting/db:/var/lib/postgresql/data osm2pgrouting \
--input /data/your_osm_file.pbf \
--dbname pgrouting \
--host localhost \
--port 5432 \
--user postgres \
--password your_password \
--create_tables \
--create_indexes \
--drop_old_data
Understanding the "Killed" Error:
The "Killed" error usually indicates that the process has been terminated due to insufficient resources, most likely memory (RAM). While increasing the swap file size can help, it's a temporary fix. The problem lies deeper, within the Docker container's limitations or the way osm2pgrouting manages resources.
Possible Causes and Solutions:
Here's a breakdown of common causes and their corresponding solutions:
-
Insufficient Container Memory: Docker containers have a limited amount of memory allocated by default. If
osm2pgroutingrequires more memory than allotted, it will be killed.- Solution: Increase the memory limit for your Docker container using the
-mflag:
docker run -it -m 16g ... # Allocate 16GB of RAM - Solution: Increase the memory limit for your Docker container using the
-
High Memory Usage: Even with sufficient container memory,
osm2pgroutingmight consume a large amount of RAM during its processing.- Solution: Optimize your OpenStreetMap data to reduce its size:
- Simplify geometry: Remove unnecessary details, like small islands or complex shapes.
- Filter data: Select only relevant road types for your analysis.
- Use smaller data chunks: Process the data in smaller sections to reduce memory pressure.
- Solution: Optimize your OpenStreetMap data to reduce its size:
-
Swap File Configuration: While increasing the swap file can temporarily provide more memory, relying heavily on it can slow down the process.
- Solution: Optimize your swap file configuration for performance:
- Increase swap file size: Allocate more swap space for larger datasets.
- Adjust swap priority: Prioritize the use of RAM over swap to avoid performance bottlenecks.
- Solution: Optimize your swap file configuration for performance:
-
Docker Container Limitations: Docker containers have limitations in their resource management, which can contribute to the "Killed" error.
- Solution: Consider alternatives to Docker:
- Virtual Machines: Provide more control and flexibility over resource allocation.
- Bare-metal installation: Install
osm2pgroutingdirectly on your server for maximum resource control.
- Solution: Consider alternatives to Docker:
Practical Example:
Let's say you're working with a large OpenStreetMap dataset for a city. You've increased the swap file, but osm2pgrouting still fails. By analyzing the docker stats output, you discover that the container is using close to its maximum memory limit. This suggests that the issue lies in insufficient container memory. You increase the memory limit to 16GB using the -m flag and rerun the command. This time, osm2pgrouting successfully completes, generating the road network topology.
Further Resources:
- osm2pgrouting documentation: https://github.com/pgRouting/osm2pgrouting
- Docker documentation: https://docs.docker.com/
- OpenStreetMap data simplification tools: https://wiki.openstreetmap.org/wiki/Data_Simplification
Conclusion:
Debugging the "Killed" error during osm2pgrouting requires understanding the root cause. It's crucial to address memory issues by adjusting container resources, optimizing data, and configuring the swap file effectively. Consider alternative containerization methods if necessary. By following these guidelines, you can successfully create your road network topology using osm2pgrouting and unlock the power of geographic data for your projects.
