elastic/logstash

LogStash should call shutdown hooks

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#5174 opened on Apr 22, 2016

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 (2 comments) (0 reactions) (0 assignees)Ruby (14,197 stars) (3,496 forks)batch import
bughelp wanted

Description

Currently, LogStash will shutdown by waiting for events to flush out and then call do_close on plugins. If --allow-unsafe-shutdown is specified then LogStash shutdown watcher will call Kernel.exit after some time.

However, ZeroMQ plugins will block under certain condition (this is by design of ZeroMQ), thus events will never flush out and do_close will never be called. The way to unblock the sockets is by terminating the ZeroMQ context. This can be done allowing a shutdown hook to be called before exiting forcefully.

Contributor guide

Tech stack
None
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
LogStash plugin architectureZeroMQ socket lifecycle
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate the LogStash shutdown sequence in the main runner code (e.g., 'logstash/runner.rb' or 'logstash/agent.rb'). Look into how currently 'do close' is called on plugins and where 'Kernel.exit' is invoked. Then design a shutdown hook mechanism that allows ZeroMQ context termination before forceful exit. Check the ZeroMQ Ruby bindings for context termination API.