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Strange measurement increase


#1

As one can see here https://graphhopper.com/measurement/#graph

image

there is a huge increase somewhen in March. But when I try to find the causing commit all results seems to be within 260s and 280s.

I also tried the commit from March, where the import time was around 170s at that time and the result now was also 280s.

There was no hardware change, even a restart of the machine did not help. One guess could be an increase due to a linux software update, but the increase is so massive that it seems to be unlikely. Additionally I increased -Xmx as sometimes the reason for a slow down was a memory usage / GC issue (and the memory usage seemed to increase by 300mb), but also this did not fix the slow down.

Any other guess?


#2

Did you change anything else like JVM, GC, etc.?

It might also be a hardware issue, for example a damaged drive that slows everything down.


#3

The JVM might have changed but only within the jdk8 cycle. But you are right probably it is time to try some new hardware.


#4

There was an increase also for purely CPU based operations I guess it could be also the slow down of meltdown patches of the linux OS.


#5

That’s also what I suspect. It could be a problem with meltdown/spectre patches and that the import heavily benefits of specilative calculations.