| layout | default_md |
|---|---|
| title | Message Expiry |
| title-class | page-title-classic |
| type | classic |
Features > Message Features > Message Expiry
Apache ActiveMQ Classic handles message expiry in two parts:
- The client sets the expiration time when it sends the message.
- The broker checks that expiration time and discards expired messages.
When a JMS producer sets a time-to-live (TTL), ActiveMQ Classic converts that TTL into an absolute JMSExpiration value when the message is sent. A TTL of 0 means the message never expires.
At the broker, expired messages can be removed in several places, including when a message arrives, while messages are being held for dispatch, and during periodic destination scans. Consumers may also filter expired messages before delivery.
In JMS, message expiration is controlled by the producer:
ActiveMQ Classic stores the TTL as an absolute expiration timestamp on the message. That timestamp is based on the sending machine's clock.
The broker checks the stored expiration timestamp against its own clock and removes expired messages as they are encountered. Because of that, expiry is not purely a client-side concept: the broker still has to enforce it.
For that reason, the clocks on all machines involved — producers, brokers, and consumers — should be kept in sync. If the machines are not time-synchronized, a message may appear to expire early or late depending on which clock is ahead.
The ActiveMQ Classic client also performs expiry checks before delivering messages to application code. This helps prevent expired messages from being consumed accidentally.