Hangs possible because of Queue.doPageIn
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Key: AMQ-2413
URL: https://issues.apache.org/activemq/browse/AMQ-2413
Project: ActiveMQ
Issue Type: Bug
Components: Broker
Affects Versions: 5.4.0
Environment: 5.4 branch 818147. Some changes after this hide this
error, but I'm still concerned it might be a problem.
Reporter: Colin MacNaughton
Priority: Critical
I don't understand the intent of the following code in Queue.doPageIn() and in
rev 818147 it was causing delivery to the consumer to get hung (temporarily
until message expiration check kickstarts it again). See the commented out
lines of code that determine how many messages to attempt to page in.
{code}
private List<QueueMessageReference> doPageIn(boolean force) throws
Exception {
List<QueueMessageReference> result = null;
List<QueueMessageReference> resultList = null;
synchronized(dispatchMutex) {
//WHAT IS THIS DOING?
//int toPageIn = getMaxPageSize() + Math.max(0,
(int)destinationStatistics.getInflight().getCount()) -pagedInMessages.size();
//DOES THIS MAKE MORE SENSE:
int toPageIn = Math.min(getMaxPageSize(), messages.size());
if (LOG.isDebugEnabled()) {
LOG.debug(destination.getPhysicalName() + " toPageIn: " +
toPageIn + ", Inflight: "
+ destinationStatistics.getInflight().getCount()
+ ", pagedInMessages.size " + pagedInMessages.size());
}
//WHAT IS THIS DOING?
//toPageIn = Math.max(0, Math.min(toPageIn, getMaxPageSize()));
if (isLazyDispatch()&& !force) {
// Only page in the minimum number of messages which can be
dispatched immediately.
toPageIn = Math.min(getConsumerMessageCountBeforeFull(),
toPageIn);
}
{code}
It is definitely possible that I'm just not understanding the intent of the
code, but whatever it is, it's not working, and consequently I'm not sure that
the subsequent fixes on the branch have eliminated the problem. The attached
patch contains both a unit test, that tests several combinations of ack mode,
vm cursoring, and delivery mode, as well as version of Queue which should be
applied against revirion 818147 -- this version has the fix commented out and
preserves the buggy behavior
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