Measuring Message Size

[Sara Murphy]

Hey folks,

We're upgrading our RabbitMQ version from 3.7.15 -> 3.8.11, and about the only breaking change between those versions is deprecating node_health_check and the max message size in 3.8.

I know we can adjust the message limit, but I'm not finding a lot of information on how to measure message sizes. Is this something that would need to be done at the publisher/consumer application level? I know I can hit the admin UI to get a specific message, and view its size, or use the firehose to inspect messages. I also know that I can measure the size of the queue in bytes and divide by # of messages to get the average message size, but that still wouldn't tell me if a single message was above the 128MiB limit.

How have you all approached this problem? Just upgraded and YOLO'd it? It seems unlikely any messages we send hit that point, but obviously I don't want to assume that in advance.

Cheers,

Sara

[Luke Bakken]

Hi Sara,

Others will hopefully chime in if they specifically address this
scenario in their environment. You are correct in that it's easiest to
keep track of message size in your producers and consumers. RabbitMQ
does not provide this information.

If a message is published that exceeds the maximum a
PRECONDITION_FAILED error is returned and the channel is closed. It is
logged as well.

Thanks,
Luke

[jo...@cloudamqp.com]

Scan the message stores for files larger than X MiB.