[CONF] Apache Qpid: Java Broker Design - Operation Logging (page created)

[confluence]

Page Created : qpid : Java Broker Design - Operation Logging Java Broker Design - Operation Logging has been created by Martin Ritchie (Jun 25, 2009). Content: Operation Logging The current logging configuration in the Java broker is focused for developers. Logging is performed on a class basis and so as a result it is not easy to enable logging to get an operation view of the broker. Some work has been done to create configuration files that set the levels on various classes to provide an operation view of the broker (see Debug with Log4j). While this provides some good detail it does not provide the full picture. The page will document the logging information that would be useful to provide, a suggested approach that should be followed and guidelines to developers for adding operational logging messages. Overview Logging Content Status Updates VirtualHost MessageStore Connection Queue Exchange Subscription Statistics updates VirtualHost Statistics MessasgeStore Statistics Connection Statistics Queue Statistics Exchange Statistics Subscription Statistics Logging format Logging Hierarchy Guidelines for logging changes Dos Don'ts Overview Currently logging is performed added in an ad-hoc manner by the devloper, ususlly to assist in the developemnt of the code base. Log messages should be aimed at helping to provide users and/or support staff with information on the health of the broker; and - in the case where there has been some issue - help them diagnose the cause of that issue. As such these messages should be readable without knowledge of the Qpid code base, they should not be so frequenet as to impact the performance of the broker but should be frequent enough such that diagnosis of issues is possible. Log messages should occur whenever a significant event occurs, for instance the creation or destruction of a connection to the broker. The log message should contain enough information to be able to correlate the message with a business process event. In the case of a connection open the remote address, the login name, the virtual host, and the application id should be included in the log message. Log messages at INFO level and above are expected to be turned on in a production environment. Logging Content There are two types of logging that are valuable to the operation of a Qpid broker: State updates Statisticsl updates. Status Updates The following model objects should log updates on state changes, creation / descruction events: VirtualHost MessageStore Connection Queue Exchange Whilst this will usually mean a single log instruction for an event such as creation/destruction the models may record state that can then be reported with the periodic statistics update. The following is an example what details may be logged: VirtualHost Number of active connections Total number of connection made Incoming message (count / bytes) Outgoing message (count / bytes) Last Activity MessageStore Disk space used Memory used Entities Stored (Queue, Exchange, Binding, Message) Total Incoming message (count / bytes) Total Outgoing message (count / bytes) Last Activity Connection Number of sessions Number of consumers Total Incoming message (count / bytes) Total Outgoing message (count / bytes) Last Activity Queue Subcription count Binding Count Current Queue size (count / bytes) Messages sent (count / bytes) Last Activity Exchange Bound queues Total Messages sent (count / bytes) Last Activity Subscription Total Messages sent (count / bytes) Unacknowledged size (count / bytes) Last Activity Statistics updates In addition to status events being logged, we should periodically log statistics. Each model object may have a set of statistics that they wish to report but it is expected that the statistics will be based on the period between logs. VirtualHost Statistics Incoming message rate (count / bytes) Outgoing message rate (count / bytes) Min / Max / Average message size MessasgeStore Statistics Incoming message rate (count / bytes) Outgoing message rate (count / bytes) Min / Max / Average message size Connection Statistics Incoming message rate (count / bytes) Outgoing message rate (count / bytes) Min / Max / Average message size Queue Statistics Incoming message rate (count / bytes) Outgoing message rate (count / bytes) Min / Max / Average message size Exchange Statistics Message rate (count / bytes) Min / Max / Average message size Subscription Statistics Outgoing message rate (count / bytes) Min / Max / Average message size As will be mentioned in the guidelines section, any collection and reporting must be mindful of the performance overhead in doing so. Logging format To reduce the amount of lookups required each log statement should include all the information required to understand the context of the message. e.g. A subscription log statement should include details about the associated connection, vhost, channel and queue. In order to keep the amount of data logged to the essential the message should be short and unambiguous - but easily recognisable. So the following formats are recommend for each model: Conection "con-<ip><username><UID>" : the UID will allow the disabmbigiuation if the same client has more than one connection. VirtualHost "vh-<name>" Channel "c-<name>" queue "q-<name>" subscription "s-[<selector>][-<properties>]-<UID>" : again a UID is required here to disabmbiguate multiple subscriptions. Logging Hierarchy When looking at augmenting the logging of the broker it makes sence to take a step back and provide an operational based logging hierarchy qpid. in addition to the developer focused org.apache.qpid.. The hierarchy of loggers should be structured such that it is easy to enable start or stop monitoring at runtime. The suggested heirarchy is as follows. qpid -+-> Connection ---> Subscription | \ Guidelines for logging changes Dos Don'ts

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