apache/pulsar

Broken subsequence of delayed messages

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#14,721 opened on Mar 16, 2022

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 (13 comments) (0 reactions) (1 assignee)Java (3,485 forks)batch import
help wantedtype/bug

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Description

Describe the bug Delayed messages to shared topic breaks subsequence of messages and delivered earlier than expected.

To Reproduce Steps to reproduce the behavior:

  1. Setup local standalone pulsar
  2. Send messages every 20ms with the same deliverAt timestamp 10000ms and with payload of millisecond when sending was started.
  3. Log received messages payload.

I start receiving all messages after 9 seconds and it I have in log:

9001ms
1ms
21ms
41ms
61ms
81ms
...
8981ms
(here should be 9001ms)
9021ms
9041ms
...

Expected behavior Two expectations:

  1. Most important I expect first message to be received is message '1ms' and message '9001ms' after '8981ms'.
  2. I expect start receiving messages after 10 seconds

Issue is reproduced in 2.8.0 and 2.9.1

Contributor guide

Research direction
Investigate the delayed message delivery mechanism in Pulsar, focusing on how messages with the same deliverAt timestamp are ordered and processed. Check the code in the message dispatch path, particularly the delay queue or timer handling, to understand why messages are delivered earlier than expected and why the first message received is not the earliest timestamp.
Tech stack
java
Domain
backend
Issue type
Bug
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.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
JavaMessaging systems
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60