1.2.3. Messaging Broker Memory Requirements

Procedure 1.4. Estimate message size

1. Default message header content (such as Java timestamp and message-id): 55 bytes
2. Routing Key (for example: a routing key of "testQ" = 5 bytes)
3. Java clients add:
   • content-type (for "text/plain" it is 10 bytes)
   • user-id (user name passed to SASL for authentication, number of bytes equal to string size)
4. Application headers:
   • Application header overhead: 8 bytes
   • For any textual header properties: property_name_size + property_value_size + 4 bytes

Procedure 1.5. Determine message size from logs

1. Enable trace logging by adding the following to /etc/qpid/qpidd.conf:

   log-enable=trace+:qpid::SessionState::receiverRecord
   log-enable=info+
   log-to-file=/path/to/file.log

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   Note that this logging will consume significant disk space, and should be turned off by removing these lines after the test is performed.
2. (Re)start the Broker.
3. Send a sample message pattern from a qpid client. This sample message pattern should correspond to your normal utilization, so that the message header and body average sizes match your projected real-world use case.
4. After the message pattern is sent, grep in the logfile for log records:

   2012-10-16 08:56:20 trace guest@QPID.2fa0df51-6131-463e-90cc-45895bea072c: recv cmd 2: header (121 bytes); properties={{MessageProperties: content-length=9; message-id=d096f253-56b9-33df-9673-61c55dcba4ae; content-type=text/plain; user-id=guest; application-headers={property1:V2:6:str16(value1),property2:V2:6:str16(value2)}; }{DeliveryProperties: priority=4; delivery-mode=2; timestamp=1350370580363; exchange=; routing-key=testQ; }}

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   This example log entry contains both header size (121 bytes in this case) and message body size (9 bytes in this case, as content-length=9).