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From "Rob Godfrey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (QPID-8238) [Broker-J] Improve performance of asynchronous publishing of transient messages into topic exchange having queues bound using non-overlapping selectors
Date Mon, 03 Sep 2018 09:28:00 GMT

    [ https://issues.apache.org/jira/browse/QPID-8238?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16601936#comment-16601936

Rob Godfrey commented on QPID-8238:

[~alex.rufous] Did you test the performance after your patch?  I started looking at the same
sort of change, but then also expanded it because for the broker the FieldTable really doesn't
need to be mutable... and then I was looking at maybe only decoding fields that were actually
queried (the advantage there being you could potentially skip decoding fields that were never
looked at, and you could also actually avoid creating a String instance, e.g. something like
this massively simplified pseudo code:

Object get(String key)
    Object value = _map.get(key);
    if(value == null && !_map.containsKey(key))
        byte[] bytesKey = getUTF8Value(key);
        value = getValueForKey(bytesKey);
        _map.put(key, value);
    return value;

> [Broker-J] Improve performance of asynchronous publishing of transient messages into
topic exchange having queues bound using non-overlapping selectors 
> --------------------------------------------------------------------------------------------------------------------------------------------------------
>                 Key: QPID-8238
>                 URL: https://issues.apache.org/jira/browse/QPID-8238
>             Project: Qpid
>          Issue Type: Improvement
>          Components: Broker-J
>    Affects Versions: qpid-java-broker-7.0.6
>            Reporter: Alex Rudyy
>            Priority: Major
>             Fix For: qpid-java-broker-7.1.0
>         Attachments: 0001-QPID-8238-Use-java.lang.String-for-keys-and-values-i.patch
> The performance of asynchronous publishing of transient messages into topic exchange
which routes messages into queues bound using non-overlapping selectors is 2-3 times slower
than performance of 0.32 broker. The performance degradation is observed with AMQP 0.9, though,
I suspect that the AMQP 0-10 protocol could be affected as well.
> I was running tests with 10 concurrent producers publishing messages  on separate connections
using the same routing key into 10 different queues (subscribers queues) bound to the exchange
using non-overlapping selectors.
> My testing showed that performance of 7.0 broker for this particular use case was 2-3
times worse than performance of 0.32 broker.
> The following factors contributed to degradation of performance:
> •	Copying data from direct memory into heap memory whilst decoding message headers.
Due to this factor, the decoding of message headers is around twice slower. It seems it contributes
around 70% to total performance degradation
> •	The message routing algorithm is slower due to need to support a new feature to route
messages into bound exchanges (in addition to queues) using replacement routing key.
> •	AMQ short strings caching contributes 5-10% to total performance degradation. The
caching was added to manage heap space more efficiently.
> The numbers provided here could be inaccurate due instrumentation overhead whilst profiling
the issue.
> Potentially, caching can be turned off but that will not improve performance much.
> On other hand, adding of additional caching of strings to amqp-short-strings would improve
the performance a bit. Whilst evaluating selectors, the fields used in selector expressions
are represented as java strings but they get converted every time into amqp-short-strings
when looking up for message header values. If 10 queues are bound to the exchange using the
same binding key, the selector expression is evaluated 10 times for the incoming message.
Thus, all selector field names are get converted into amqp-short-strings 10 times as well.
It seems adding caching here can improve the performance. 

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