Hi all,
so on my trip home a few days ago I managed to also get the serialization
running. I now am able to parse a byte message
into a model and deserialize the model back to bytes and the byte arrays are
equal. However the serialization performance
I am not that happy with as it takes quite a lot longer to serialize than to
parse, which shouldn't be the case.
The main reason is, that while simply reading the implicit fields during the
parsing, when serializing them, a lot of
Evaluations executions have to be performed.
They are usually quite simple expressions such as this:
exItems = jexl.createExpression("parameter.numItems");
The best option would be to improve the antlr grammar to parse the expressions
a little more formally correct and to implement a model for these expressions
and have them automatically translated to code like:
this.getParameter().getNumItems();
It should be possible and a lot faster ... anyone up for the challenge?
@Julian? .. could you please help with this?
As you did that great job with the initial spec ANTLR grammar.
Chris
Am 05.06.19, 10:09 schrieb "Christofer Dutz" <[email protected]>:
Hi all,
In the train today I'll be working on the serialization (Which will be a
challenge)
But I am sure this will be a lot of hard work but also a great step forward.
Is there any progress on the Driver-Logic generation front?
Otherwise I would probably try to whip up a hand-written Netty layer using
the generated model.
Without all the parser/serializer code this should only be a fragment of
the existing driver code.
Chris
Am 05.06.19, 09:59 schrieb "Strljic, Matthias Milan"
<[email protected]>:
Hura sounds nice 😉
I hope I find time to play a bit around with it in the next few days.
Greetings
Matthias Strljic, M.Sc.
Universität Stuttgart
Institut für Steuerungstechnik der Werkzeugmaschinen und
Fertigungseinrichtungen (ISW)
Seidenstraße 36
70174 Stuttgart
GERMANY
Tel: +49 711 685-84530
Fax: +49 711 685-74530
E-Mail: [email protected]
Web: http://www.isw.uni-stuttgart.de
-----Original Message-----
From: Christofer Dutz <[email protected]>
Sent: Tuesday, June 4, 2019 4:16 PM
To: [email protected]
Subject: [CodeGen] Performance values
Hi all,
so as I mentioned in Slack yesterday I was able to successfully parse a
S7 packet with the code generated by the code-generator.
There I am using Apache Jexl for evaluating the expressions we are
using all over the place. It got things working quite easily.
However my gut-feeling told me all these Jexl evaluators I’m creating
can’t be that ideal.
But not wanting to pre-maturely optimize something that’s already good,
I did a measurement:
So I did a little test, in which I let my parser parse one message
20000 times.
It came up with an average time of 0,8ms … this didn’t sound too bad
compared to the about 20ms of the interpreted daffodil approach.
But is this already good? It’s probably not ideal to compare some
results with the ones we know are bad, instead I wanted to compare it to the
ones we are proud of.
In order to find out I whipped up a little manual test with the
existing S7 driver.
For this I simply plugged the 3 layers together with an Embedded
channel and used a custom handler at the end to return the message.
This seems to work quite nicely and I was able to run the same test
with the Netty based S7 driver layers we have been using for the last 2 years.
The results were:
Parsed 20000 packets in 796ms
That's 0.0398ms per packet
So this is a HUGE difference .
As one last check I ran JProfiler over the benchmark and it confirmed
that 87% of the time was used by Jexl.
However the creation of Jexl expressions, not their evaluation.
So one optimization I’ll try is to do, is to have the expressions
created statically and then to simply reference them.
This will increase the complexity of the template, but should speed
things up.
And I’ll also change the code I’m generating for the Type-Switches to
work without jexl.
Simply assuming this would eliminate the time wasted by jexl (great
simplification), we would reduce the parse time to 0,1ms which is still about 3
times that of the existing driver.
I am assuming that this might be related to the BitInputStream I am
using … but we’ll deal with that as soon as we’re done with getting rid of the
time wasted by Jexl.
So far an update on the generated-drivers front.
Chris
