When use exact-once-delivery, and allowExcessMessages is false, nacking a number of messages equal to maxMessages subscriber stop of receive messages #2070
Description
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A screenshot that you have tested with "Try this API".
Video reproducing bug
Screen.Recording.2025-07-19.at.08.53.06.mov
Link to the code that reproduces this issue. A link to a public Github Repository or gist with a minimal reproduction.
https://github.com/Luisgustavom1/pubsub-bug-reprodution
A step-by-step description of how to reproduce the issue, based on the linked reproduction.
Start a subscriber, setting flowControl, with maxMessages and allowExcessMessages
const subscription = pubsub.subscription("subscription-name", {
flowControl: {
maxMessages: 2,
allowExcessMessages: false
}
});
console.log(`Listening for messages on subscription`);
subscription.on('message', async message => {
const n = Number(message.data)
console.log('Received message:', n);
if (n % 2 === 0) {
await message.ackWithResponse();
console.log('ack successfully');
} else {
await message.nackWithResponse();
console.log('nack successfully');
}
});When start send mensagens to topic, after two nacks (number equal of maxMessages) subscriber stop of receiving new messages
A clear and concise description of what the bug is, and what you expected to happen.
Subscriber should continue receiving messages
A clear and concise description WHY you expect this behavior, i.e., was it a recent change, there is documentation that points to this behavior, etc. **
Its a bug because subscriber will never receive any more messages