This is best practice and will prevent unlock from being attempted
inside of a finally block when the thread doesn't actually own the
lock which can happen when the lock attempt throws an exception
such as calling lockInterruptibly()
A store directory is created by MessageDatabase#getPageFile which
is called in two cases:
1. KahaDBStore.start() when creating a queue
2. KahaDBStore.size() which is performed when sending any persistent message
If both methods are called concurrently it's possible to get an IOException
thrown from the IOHelper.mkdirs method.
Topic subscriptions expire a message
This fixes topic subs to send the right advisory type, if enabled, when
the server discards a message on dispatch to a topic sub. Also add some
more expiration tests for other subscription types
current dispatched count
The previous way of computing the count of using total dispatched minus
total dequeued didn't work in the case of destination removal and
messages were not acked. The counter is needed as the dispatched list is
optional unlike prefetch subs.
The dispatched advisory doesn't really make sense to send for queue
browsers, just like we don't send a consumed advisory, as it's more of
an admin type funtion to look at the contents of a queue but it's not a
real consumer that is receiving and acking messages.
managed region broker
This new approach just looks matching Subscriptions from the region for the
destination which prevents having to store another map and falls back to
the old approach if something went wrong.
Due to changes with Queues to check if consumers are full before adding
more messages to the subscription, the Queue dispatch logic needed to be
updated to mark subscriptions as slow and send advisories if configured
instead of relying on the subscription itself to do it.
If you have an application that creates lots of queues it will eventually
fail with OOM because TempUsage is started on Queue#start but never stopped.
The `systemUsage.getTempUsage().start()` used on the Queue#start
adds elements on a List from TempUsage parent and these elements
are never removed.
To reproduce this issue you need to leave an application
running for a long time creating different queues.
The only way to avoid the leak right now is to stop the BrokerService,
which isn't a solution.
Adding a feature (STATS_FIRST_MESSAGE_TIMESTAMP) to the
StatisticsBrokerPlugin's destination-statistics for getting the
timestamp of the first message in the destination(s) being requested: If
you on the query-message set the property
StatisticsBroker.STATS_FIRST_MESSAGE_TIMESTAMP to anything (e.g. boolean
true), a long value "firstMessageTimestamp" will be added to the
statistics reply message(s). Since the reply message has JMSTimestamp
set, which is the broker's now-timestamp, you may also on the query side
calculate the age of the first message in milliseconds. The key name was
chosen since that is the name of the corresponding feature in Artemis.
This extension of the existing feature is implemented to be as
non-intrusive as possible, adding very little runtime cost if not
requested. It also seems like the runtime cost for enabling this
feature, thus finding and adding the firstMessageTimestamp, is small.
While at it, also slightly improving an existing feature
(STATS_DENOTE_END_LIST) where a reply to a destination query can be
"null terminated": After sending the relevant replies, the
StatisticsBroker also sends an empty message. This feature is relevant
if the query is a wildcard query, thus returning multiple messages: The
empty message denotes the end of the replies. However, to activate this
feature, a somewhat complicated query destination had to be constructed.
Adopting the solution for the other StatisticsBroker feature where you
may reset the broker statistics by adding a property to the query
message, this null-termination feature now /also/ checks for the
presence of this query modifier STATS_DENOTE_END_LIST as a property.
(This property based solution was thus also adopted for the present
'firstMessageTimestamp' solution, as it was found much more intuitive).
Added tests for both the STATS_FIRST_MESSAGE_TIMESTAMP query modifier,
and the improved STATS_DENOTE_END_LIST property-based query modifier.
Had to make the Topic.doBrowse(List browseList, int max) public - the
corresponding method for Queue was already public.
Made the evaluation of whether this is a StatisticsBroker-relevant
message a microscopic bit more performant (exiting faster if not
relevant): To the initial test of whether the message is relevant, which
only checked for replyTo being set, a check for 'destination.
startsWith("ActiveMQ.Statistics")' was added. Only if so, the rest of
the evaluations kick in. Also using 'string.startsWith(..)' instead of
the verbose 'string.regionMatches(..)'.
Removed an unused import on PartitionBrokerTest.java, as IntelliJ
complained about not finding it.
JB Onofré
Jean-Baptiste Onofré
Matt Pavlovich
Christopher L. Shannon (cshannon)
Michał Janczykowski
Dmytro Chebotarskyi
Lucas Tétreault
Robbie Gemmell
Zishuo Ding
Artur Pedroso
Endre Stølsvik