11.1.2 Passing the Configuration File to the Graph Server (PGX)

The PGX engine configuration file is parsed by the graph server at startup-time whenever ServerInstance#startEngine (or any of its variants) is called. You can write the path to your configuration file to the graph server (PGX) or perform it programmatically. This topic explains the different ways to pass the PGX engine file to the graph server (PGX):

Programmatically

All configuration fields exist as Java enums. Example:

Map<PgxConfig.Field, Object> pgxCfg = new HashMap<>();
pgxCfg.put(PgxConfig.Field.MEMORY_CLEANUP_INTERVAL, 600);

ServerInstance instance = ...
instance.startEngine(pgxCfg);

All parameters not explicitly set will get default values.

Explicitly Using a File

Instead of a map, you can write the path to a PGX configuration JSON file. Example:

instance.startEngine("path/to/pgx.conf"); // file on local file system
instance.startEngine("classpath:/path/to/pgx.conf"); // file on current classpath

For all other protocols, you can write directly in the input stream to a JSON file. Example:

InputStream is = ...
instance.startEngine(is);

Implicitly Using a File

If startEngine() is called without an argument, the graph server (PGX) looks for a configuration file at the following places, stopping when it finds the file:

• File path found in the Java system property pgx_conf. Example: java -Dpgx_conf=conf/my.pgx.config.json ...

• A file named pgx.conf in the root directory of the current classpath

• A file named pgx.conf in the root directory relative to the current System.getProperty("user.dir") directory

Note: Providing a configuration is optional. A default value for each field will be used if the field cannot be found in the given configuration file, or if no configuration file is provided.

Using the Shell in Embedded Mode

To change how the shell configures the embedded (local) graph server (PGX) instance, edit $PGX_HOME/conf/pgx.conf. Changes will be reflected the next time you invoke $PGX_HOME/bin/pgx.

You can also change the location of the configuration file as in the following example:

./bin/opg --pgx_conf path/to/my/other/pgx.conf

Setting System Properties

Any parameter can be set using Java system properties by writing -Dpgx.<FIELD>=<VALUE> arguments to the JVM that the graph server (PGX) is running on. Note that setting system properties will overwrite any other configuration. The following example sets the maximum off-heap size to 256 GB, regardless of what any other configuration says:

java -Dpgx.max_off_heap_size=256000 ...

Setting Environment Variables

Any parameter can also be set using environment variables by adding 'PGX_' to the environment variable for the JVM in which the graph server (PGX) is executed. Note that setting environment variables will overwrite any other configuration; but if a system property and an environment variable are set for the same parameter, the system property value is used. The following example sets the maximum off-heap size to 256 GB using an environment variable:

PGX_MAX_OFF_HEAP_SIZE=256000 java ...