Hello.
This question is about how to configure JBossMQ to cope with a huge flood of messages
that are NON_PERSISTENT.
Assumptions:
- A NON_PERSISTENT message does not have to be stored persistently, server may
drop/lose some. The javadoc says:
anonymous wrote :
| This is the lowest-overhead delivery mode because it does not require
| that the message be logged to stable storage. The level of JMS provider
| failure that causes a NON_PERSISTENT message to be lost is not defined.
- The MessageCache is good since it stops me hitting a OutOfMemoryException
- It is fatal (from a performance standpoint) for the cache to begin storing messages
to secondary storage.
This will only make the situation worse if we are being flooded with messages.
Questions and attempted answers:
Q1) When does JBoss drop NON_PERSITENT messages?
A1) Reboot i presume?
Q2) Can the NullPersistenceManager be used in this scenario?
A2) I don't think so since it stores all the messages in a Map in memory and will not
drop messages.
So we'll start running out of memory [i tried this, see below].
Q3) If my requirement is for JBoss to still be responsive when i get a flood of
messages and
i'm happy to lose messages what are my options?
A3) I imagine i could write my own org.jboss.mq.pm.PersistenceManager/CacheStore whose
implementation
of saveToStorage() just loses the message.
I would be very grateful for input/feedback on these questions/answer attempts.
I did try replacing deploy/jms/hsqldb-jdbc-service.xml with
examples/jms/null-persistence-service.xml
and running my stress client with the default jvm heap size. What i observe is that
the CPU hits 100%.
If i enable tracing i very rapidly get GIGA bytes of logs. Looking at them there is an
awful lot of the following:
| 2004-07-22 16:53:24,187 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,187 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,187 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,187 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,187 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
|
| ...
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.TracingInterceptor] CALLED :
transact
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.TracingInterceptor] ARG :
[EMAIL PROTECTED]
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.BasicQueue] acknowledge
AcknowledgementRequest:ACK,TOPIC.testTopic,ID:21-1090507594531644 12614 [EMAIL
PROTECTED]:1.-2147483648}
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.TracingInterceptor] RETURN :
transact
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.TracingInterceptor] CALLED :
receive
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.TracingInterceptor] ARG :
-2147483648
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.TracingInterceptor] ARG : -1
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.security.ServerSecurityInterceptor]
Checking receive authorize on ConnectionToken:ID:1/0936deaa2c42a73e515828be586c1022
subId=-2147483648
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.security.SecurityManager] Checking
authorize on subjectInfo: SubjectInfo {subject=Betreff:
| Principal: guest
| Principal: Roles(members:j2ee,guest,john)
| ;principal=null;roles=Roles(members:j2ee,guest,john) for rolePrincipals
[durpublisher, publisher, guest]
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.BasicQueue] receive
Subscription[subId=-2147483648connection=ConnectionToken:ID:1/0936deaa2c42a73e515828be586c1022
destination=TOPIC.testTopic messageSelector=null Local Create] wait=false [EMAIL
PROTECTED]:1.-2147483648}
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.SpyXAResource] Start xid=XidImpl
[FormatId=257, GlobalId=jboss-laptop//12655, BranchQual=], flags=0 [EMAIL PROTECTED]
txid=-9223372036854763180 XA RUNNING [EMAIL
PROTECTED]:ID:1/0936deaa2c42a73e515828be586c1022 rcvstate=STARTED]]]
| ...
|
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
| 2004-07-22 16:53:24,687 TRACE [org.jboss.mq.server.MessageReference] saveToStorage
rejected by cache 12630 msg=12629 hard NOT_STORED NON_PERSISTENT
queue=TOPIC.testTopic.ID:1.-2147483648 priority=4 lateClone=false hashCode=14952304
|
the saveToStorage appears over 14000 times for msg=12629. I rekon this is where the
CPU is spending the time.
I found the code that does it, but don't really know whats going on here:
| void makeSoft() throws JMSException
| ...
| // HACK: allow the jdbc2 driver to reject saveToStorage for persistent
messages
| // it is just about to persist the message when it gets some cpu
| if (stored != STORED)
| {
| if (trace)
| log.trace("saveToStorage rejected by cache " + toString());
| return;
| }
|
|
cheers
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