Hello,
I'm looking into JSR223 samplers performance and here are my findings.
The question is "what is the expected behavior of JSR223
samplers/assertions/etc in regard to global variables?"
In other words, what if sampler A defines new global and a subsequent
sampler B tries to access it.
1) It might take a while to instantiate a ScriptEngine.
That's simple: just a thread local (or a Map<String, ScriptEngine>
field in the JMeterThread).
2) It might take a while to initialize script context (see below).
3) It is strange that compilation keys have to be manually specified.
Does it really make sense to ask user to specify cache key?
What if JMeter created cache key automatically?
Here's more on #2
For instance, consider JavaScript: when it initializes, it needs to
populate "global scope" with all the defaults (RegExp, Number, String,
etc, etc).
It might happen script itself defines some global variables or
redefines out of the box ones.
Here's the script I use to measure the performance (JDK 1.8u40,
engine==javascript):
var tmp
for(var i=0; i<300; i++) {
tmp = vars.get("TESTSTART.MS"); vars.put("TESTSTART.MS", tmp);
}
It takes ~1.2 seconds when executing this loop 1000 times (300'000
puts & gets) with all defaults (~ 4000ns per get+put)
If I cache ScriptEngine the response time reduces to 600ms (~ 2000ns
per get+put)
If I additionally reuse ScriptContext the response time reduces to
30ms (~ 100ns per get+put)
So, the question boils down to:
2.1) What if we just "reuse global scope" between all the samplers in
the current thread? At the end, users should write proper code
(without global variables)
2.2) If "reuse global scope always" is considered a no-go solution,
should we add a UI checkbox to "enable/disable" sharing?
--
Regards,
Vladimir Sitnikov
