api-plugin-helper-thread.md

Plugin Helper: Thread

The thread plugin helper manages threads and these threads are integrated with plugins. No need manual run or shutdown in the plugin.

Here is an example:

require 'fluent/plugin/output'

module Fluent::Plugin
  class ExampleOutput < Output
    Fluent::Plugin.register_output('example', self)

    # 1. Load thread helper
    helpers :thread

    # Omit `configure`, `shutdown` and other plugin APIs

    def start
      super

      # 2. Create and run thread with unique name.
      thread_create(:example_thread_run, &method(:run))
    end

    def run
      # ...
    end
  end
end

The launched thread is managed by the plugin helper. No need of thread shutdown code in plugin's shutdown method. It shutdowns the launched threads automatically.

Methods

thread_create(title)

This method creates a thread and runs it with the given routine.

title must be unique.

# Pass block directly
thread_create(:example_plugin_main) {
  # ...
}

# Pass method object with existing method
thread_create(:foo_plugin_body, &method(:run))
def run
  # ...
end

thread_current_running?

Checks whether the current thread is running or not. This method is available in the running block.

thread_create(:example_plugin_main) {
  while thread_current_running?
    # ...
  end
}

Plugins using thread

• out_forward
• in_monitor_agent
• in_sample

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.