Fix race condition causing events to be lost during initialization #1090
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
…re onReady Fixed a race condition where events tracked during the onReady() processing were incorrectly categorized as pending and never sent to Segment. The bug occurred when: 1. App starts tracking events before initialization 2. During init, onReady() begins processing pending events (takes seconds) 3. New events arrive while onReady() is still running 4. These events check isReady (still false) and get saved as "pending" 5. Since onReady() already ran, these new pending events are never processed The fix simply swaps two lines to set isReady=true BEFORE calling onReady(), ensuring any events that arrive during processing go directly to the queue. Added tests to verify the initialization order and prevent regression.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR fixes a critical race condition that causes events to be lost when they are tracked while the Segment client is processing pending events during initialization.
Problem
Events tracked during the app startup phase were being lost. When the Segment client initializes, it processes any events that were tracked before it was ready (pending events).
However, due to a race condition, new events arriving during this processing period were incorrectly saved as "pending" and never sent.
Reproduction Steps
Root Cause
The
isReadyflag was being set AFTER theonReady()function completed processing pending events. This created a window where:isReady.valueisReady.valueis stillfalse, they get saved as pendingSolution
Set the
isReadyflag totrueBEFORE processing pending events, not after. This ensures any events arriving during initialization go directly to the queue.