# New Ticket Created by  Zoffix Znet 
# Please include the string:  [perl #131515]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=131515 >


Recently, we have had about ~2.7% overall performance loss, when running 
stresstest/spectest that a couple of devs noticed.
Tux's bench also showed a slowdown.

Based on stresstest timings I post ( 
https://irclog.perlgeek.de/perl6-dev/search/?nick=&q=ZOFVM ), the slowdown 
happened in
some commits made between 2017-05-31 and 2017-06-01. I tried narrowing down 
what brought the slowdown, but couldn't quite
pinpoint it, because there's some randomness in timings of some tests. Here's 
my results of test times:

SHA     Stresstest (s)  Spectest (s)
aebd0fa 123     
01d948d 122     
2500e50 121 / 122       86
79b8ab9 119 / 118       83
b879060 117 / 119       82 / 82
3f5cc5a 117     
3488914 118     
fb7dd8a 119     

As you can see, the middle commits is where the slowage appears to occur, with 
2500e50 being the most likely culprit,
even though, the code itself isn't something that would be even remotely hot.

I went and rewrote it in NQP (attached) to see if it drops the numbers at all, 
and... it didn't really.
I got a 120s stresstest and a 85s spectest.

I gave up with this.

I think we need some extensive bench without any random sleeps or delays in it 
and comprehensive enough to test more than
just a few text methods. Perhaps, something that can be cooked up with 
https://map.perl6.party/

And with such a bench in hand, it might become easier to hunt commits that slow 
stuff down considerably.

Attachment: exception.diff
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