Server Picker

SQreamDB’s load balancer is called server_picker.

Positional command line arguments

Syntax

$ server_picker [ <Metadata server address> <Metadata server port> ] [ <TCP listen port> ] [ <SSL listen port> ] [ <server picker services> ] [ <refresh_interval> ] [ <logging configuration file> ]

Parameters

Argument	Default	Description
`Metadata server address`		IP or hostname to an active metadata server
`Metadata server port`		TCP port to an active metadata server
`TCP listen port`	`3108`	TCP port for server picker to listen on
`SSL listen port`	`3109`	SSL port for server picker to listen on
`server picker services`	All services, unless specified otherwise	Defines which Worker will accept compilation jobs according to services. Accepts 1 or more services separated using a comma
`refresh_interval`	15 seconds	Examines worker availability based on the specified time interval
`logging configuration file`	`log4` logging to default log path(/tmp/logs)	Controls the format and destination of log output

Example

$ server_picker 127.0.0.1 3105 3118 3119 sqream23, sqream0 metadata_log_properties

Starting server picker

Starting temporarily

In general, you should not need to run server_picker manually, but it is sometimes useful for testing.

Assuming we have a metadata server listening on the localhost, on port 3105:

$ nohup server_picker 127.0.0.1 3105 &
$ SP_PID=$!

Using nohup and & sends server picker to run in the background.

Starting temporarily with non-default port

Tell server picker to listen on port 2255 for unsecured connections, and port 2266 for SSL connections.

$ nohup server_picker 127.0.0.1 3105 2255 2266 &
$ SP_PID=$!

Using nohup and & sends server picker to run in the background.

Stopping server picker

$ kill -9 $SP_PID

Tip

It is safe to stop any SQream DB component at any time using kill. No partial data or data corruption should occur when using this method to stop the process.