tradeoffs, bad science, and polar bears: the world of java optimisation

by Holly Cummins

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Holly Cummins Red Hat @holly_cummins tradeoffs, bad science, and polar bears: the world of java optimisation Devoxx UK

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#Quarkus @holly_cummins why optimise?

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#Quarkus @holly_cummins why optimise?

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#Quarkus @holly_cummins why optimise? 0.5s extra search page time

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#Quarkus @holly_cummins why optimise? 0.5s extra search page time 20% drop in traffic

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#Quarkus @holly_cummins why optimise? 0.5s extra search page time 20% drop in traffic 100 ms latency on page load

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#Quarkus @holly_cummins why optimise? 0.5s extra search page time 20% drop in traffic 100 ms latency on page load 7% lower conversion rate

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#Quarkus @holly_cummins why optimise? 0.5s extra search page time 20% drop in traffic 100 ms latency on page load 7% lower conversion rate

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#Quarkus @holly_cummins why optimise? 0.5s extra search page time 20% drop in traffic 10 ms delay in trading platform 100 ms latency on page load 7% lower conversion rate

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#Quarkus @holly_cummins why optimise? 0.5s extra search page time 20% drop in traffic 10 ms delay in trading platform 10% drop in revenue 100 ms latency on page load 7% lower conversion rate

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#Quarkus @holly_cummins what is optimising?

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#Quarkus @holly_cummins for whom? when? doing what? “make it go faster”

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#Quarkus @holly_cummins user-centric (technical) design

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#Quarkus @holly_cummins

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#Quarkus @holly_cummins performance can be:

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#Quarkus @holly_cummins performance can be: throughput

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#Quarkus @holly_cummins performance can be: throughput transactions per second

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#Quarkus @holly_cummins performance can be: throughput latency transactions per second

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#Quarkus @holly_cummins performance can be: throughput latency transactions per second start-up time

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#Quarkus @holly_cummins performance can be: throughput latency transactions per second response time start-up time

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#Quarkus @holly_cummins performance can be: throughput latency transactions per second response time start-up time ramp-up time

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#Quarkus @holly_cummins performance can be: throughput latency capacity transactions per second response time start-up time ramp-up time

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#Quarkus @holly_cummins performance can be: throughput latency capacity transactions per second response time start-up time footprint ramp-up time

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#Quarkus @holly_cummins performance can be: throughput latency capacity transactions per second response time start-up time CPU usage footprint ramp-up time

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#Quarkus @holly_cummins performance can be: throughput latency capacity utilisation transactions per second response time start-up time CPU usage footprint ramp-up time

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#Quarkus @holly_cummins performance can be: throughput latency capacity utilisation … transactions per second response time start-up time CPU usage footprint ramp-up time

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#Quarkus @holly_cummins Never underestimate the bandwidth [throughput] of a station wagon full of tapes hurtling down the highway. –Andrew Tanenbaum, 1981

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#Quarkus @holly_cummins Never underestimate the bandwidth [throughput] of a station wagon full of tapes hurtling down the highway. –Andrew Tanenbaum, 1981 but the latency is terrible …

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@holly_cummins requirements change

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@holly_cummins

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@holly_cummins

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@holly_cummins

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@holly_cummins

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@holly_cummins I am not designed for this.

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@holly_cummins the world changes

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#Quarkus @holly_cummins

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#Quarkus @holly_cummins -Xmx == $

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#Quarkus @holly_cummins -Xmx == $ footprint

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#Quarkus @holly_cummins

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#Quarkus @holly_cummins which performs better?

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#Quarkus @holly_cummins quarkus trading-off flexibility against (frankly, ridiculous) startup speed and footprint

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#Quarkus @holly_cummins quarkus trading-off flexibility against (frankly, ridiculous) startup speed and footprint uhh … are you supposed to shut down applications after using them?

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#Quarkus @holly_cummins which is better?

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#Quarkus @holly_cummins which is better? which is faster?

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#Quarkus @holly_cummins which is better? GraalVM Quarkus Application which is faster?

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#Quarkus @holly_cummins which is better? OpenJDK GraalVM Quarkus Quarkus Application Application which is faster?

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#Quarkus @holly_cummins which is better? ephemeral or serverless OpenJDK GraalVM Quarkus Quarkus Application Application which is faster?

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#Quarkus @holly_cummins which is better? ephemeral or serverless OpenJDK GraalVM Quarkus Quarkus Application Application running your application for a long time which is faster?

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#Quarkus @holly_cummins behaviour at idle

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#Quarkus @holly_cummins behaviour at idle is your ‘long-running’ application actually doing things?

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#Quarkus @holly_cummins 30% of VMs are zombies (antithesisgroup.com) behaviour at idle behaviour when forgotten is your ‘long-running’ application actually doing things?

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#Quarkus @holly_cummins how to optimise?

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#Quarkus @holly_cummins find the bottleneck. fix it.

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#IBM @holly_cummins intuition pitfall 1

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#Quarkus @holly_cummins this is not the place for ideas

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#Quarkus @holly_cummins measure, don’t guess.

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#Quarkus @holly_cummins measure the right thing

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#Quarkus @holly_cummins measure the right thing what do your users care about?

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#IBM @holly_cummins numbers pitfall 2

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#Quarkus @holly_cummins

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#Quarkus @holly_cummins leading indicators

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#Quarkus @holly_cummins leading indicators lagging indicators

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#Quarkus @holly_cummins leading indicators we care about them lagging indicators

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#Quarkus @holly_cummins leading indicators we care about them easy to measure lagging indicators

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#Quarkus @holly_cummins leading indicators we care about them easy to measure hard to change lagging indicators

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#Quarkus @holly_cummins leading indicators we care about them easy to measure hard to change lagging indicators easy to change

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#Quarkus @holly_cummins leading indicators we care about them easy to measure hard to change lagging indicators predictive of a thing we care about easy to change

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#Quarkus @holly_cummins leading indicators we care about them easy to measure hard to change lagging indicators predictive of a thing we care about hard to identify easy to change

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#Quarkus @holly_cummins leading indicators we care about them easy to measure hard to change lagging indicators predictive of a thing we care about hard to identify easy to change

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#Quarkus @holly_cummins caution: performance experiments for entertainment purposes only. do not try these at home.

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#Quarkus @holly_cummins 2007

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#Quarkus @holly_cummins bad-ish advice: “reduce time spent in garbage collection”

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#Quarkus @holly_cummins bad-ish advice: “reduce time spent in garbage collection” actually, garbage collection can make your application go faster

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#Quarkus @holly_cummins 2007

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#Quarkus @holly_cummins 2007

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#Quarkus @holly_cummins 2021

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#Quarkus @holly_cummins 2021

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xcompactgc

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput -Xcompactgc

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput -Xmx110m -Xms110m -Xnocompactgc

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput -Xmx160m -Xms160m -Xnocompactgc

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput -Xmx300m -Xms300m -Xcompactgc why does the performance stay exactly the same no matter what gc settings I choose?

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#Quarkus @holly_cummins by the way, this is cheating. (remember the ‘bad science’?)

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput tool: GCMV

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput total GC time: 21.6s tool: GCMV

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput total GC time: 21.6s 4.1% of time in GC pause tool: GCMV

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput total GC time: 21.6s 4.1% of time in GC pause total GC time: 12.0s tool: GCMV

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput total GC time: 21.6s 4.1% of time in GC pause total GC time: 12.0s 3.6% of time in GC pause tool: GCMV

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput total GC time: 21.6s 4.1% of time in GC pause 23.9 GB garbage collected total GC time: 12.0s 3.6% of time in GC pause 13.0 GB garbage collected tool: GCMV

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#Quarkus @holly_cummins -verbose:gc -Xverbosegclog:gclog.xml -Xgcpolicy:optthruput total GC time: 21.6s 4.1% of time in GC pause 23.9 GB garbage collected 493 transactions/s total GC time: 12.0s 3.6% of time in GC pause 13.0 GB garbage collected 260 transactions/s tool: GCMV

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#Quarkus @holly_cummins total GC time: 21.6s 4.1% of time in GC pause 23.9 GB garbage collected 493 transactions/s total GC time: 12.0s 3.6% of time in GC pause 13.0 GB garbage collected 260 transactions/s

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#Quarkus @holly_cummins so wait, what changed to make the app faster? running jmeter on the same machine as the app gives a big speedup!

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#Quarkus @holly_cummins “Any improvements made anywhere besides the bottleneck are an illusion.” – Gene Kim

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#Quarkus @holly_cummins time kills all performance advice (even mine)

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#Quarkus @holly_cummins the takeaways: gc can improve performance by rearranging the heap find the bottleneck validate advice independently

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#IBM @holly_cummins advice pitfall 3

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#Quarkus @holly_cummins I read it on the internet!

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#IBM @holly_cummins noooooo! “make one big method because method dispatching is slow”

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#IBM @holly_cummins noooooo! “re-use your objects to help the garbage collector”

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#IBM @holly_cummins noooooo! “to tune your JVM, use this command-line:” -server -Xms1g -Xmx1g -XX:PermSize=1g -XX:MaxPermSize=256m -Xmn256m -Xss64k -XX:SurvivorRatio=30 -XX:+UseConcMarkSweepGC -XX: +CMSParallelRemarkEnabled -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=10 -XX:+ScavengeBeforeFullGC -XX: +CMSScavengeBeforeRemark -XX:+PrintGCDateStamps -verbose:gc -XX: +PrintGCDetails -Dsun.net.inetaddr.ttl=5 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=`date`.hprof -Dcom.sun.management.jmxremote.port=5616 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -server -Xms2g -Xmx2g -XX:MaxPermSize=256m -XX:NewRatio=1 -XX:+UseConcMarkSweepGC

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#IBM @holly_cummins noooooo! use StringBuilder, never concatenate strings with +=

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#IBM @holly_cummins noooooo! use StringBuilder, never concatenate strings with += wait, what? yes, right?

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#Quarkus @holly_cummins 2 things ruin advice: • context • time

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#IBM @holly_cummins micro-optimisation pitfall 4

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#Quarkus @holly_cummins

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#Quarkus @holly_cummins static string beSlow() { string result = ""; for (int i = 0; i < 314159; i++) { result += getStringData(i); } return result; }

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#Quarkus @holly_cummins @Override public String toString() { String ret = "\n\tMarket Summary at: " + getSummaryDate() + "\n\t\t TSIA:" + getTSIA() + "\n\t\t openTSIA:" + getOpenTSIA() + "\n\t\t gain:" + getGainPercent() + "\n\t\t volume:" + getVolume(); if ((getTopGainers() == null) || (getTopLosers() == null)) { return ret; } ret += "\n\t\t Current Top Gainers:"; Iterator it = getTopGainers().iterator(); while (it.hasNext()) { QuoteDataBean quoteData = it.next(); ret += ("\n\t\t\t" + quoteData.toString()); } ret += "\n\t\t Current Top Losers:"; it = getTopLosers().iterator(); while (it.hasNext()) { QuoteDataBean quoteData = it.next(); ret += ("\n\t\t\t" + quoteData.toString()); } return ret; }

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#Quarkus @holly_cummins let’s make travel energy-efficient?

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#Quarkus @holly_cummins every little helps?

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#Quarkus @holly_cummins every little helps? every optimisation is another optimisation you aren’t doing

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#Quarkus @holly_cummins our platforms help

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#Quarkus @holly_cummins static string beSlow() { string result = ""; for (int i = 0; i < 314159; i++) { result += getStringData(i); } return result; }

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#Quarkus @holly_cummins static string beSlow() { string result = “"; result += getStringData(1); result += getStringData(2); result += getStringData(3); return result; }

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#Quarkus @holly_cummins static string beSlow() { string result = “"; result += getStringData(1); result += getStringData(2); result += getStringData(3); return result; } this is fine

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#Quarkus @holly_cummins the JVM writers have far more time for optimising than you do clean, typical, code runs best

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#Quarkus @holly_cummins ok, but how to optimise?

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#Quarkus @holly_cummins tools

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#Quarkus @holly_cummins “What you can optimize is limited to what you can observe.” -Susie Xia, Netflix

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#Quarkus @holly_cummins observability

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing * not free this is an incomplete list, because there are a lot of tools out there, and many cost money

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing VisualVM * not free this is an incomplete list, because there are a lot of tools out there, and many cost money

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control VisualVM * not free this is an incomplete list, because there are a lot of tools out there, and many cost money

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs VisualVM * not free this is an incomplete list, because there are a lot of tools out there, and many cost money IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs GCMV VisualVM * not free this is an incomplete list, because there are a lot of tools out there, and many cost money IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs GCMV VisualVM Eclipse MAT * not free this is an incomplete list, because there are a lot of tools out there, and many cost money IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs GCMV New Relic* VisualVM Eclipse MAT * not free this is an incomplete list, because there are a lot of tools out there, and many cost money GlowRoot IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs GCMV New Relic* AppDynamics* VisualVM Eclipse MAT * not free this is an incomplete list, because there are a lot of tools out there, and many cost money GlowRoot IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs GCMV New Relic* AppDynamics* VisualVM Dynatrace* Eclipse MAT * not free this is an incomplete list, because there are a lot of tools out there, and many cost money GlowRoot IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs GCMV New Relic* AppDynamics* Zipkin VisualVM Dynatrace* Eclipse MAT * not free this is an incomplete list, because there are a lot of tools out there, and many cost money GlowRoot IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins method profiler GC analysis heap analysis APM distributed tracing Mission Control flame graphs GCMV New Relic* AppDynamics* Jaeger Zipkin VisualVM Dynatrace* Eclipse MAT * not free this is an incomplete list, because there are a lot of tools out there, and many cost money GlowRoot IBM Health Center (for OpenJ9)

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#Quarkus @holly_cummins Netflix microservice architecture optimising a micro-service: is that micro-optimising?

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@holly_cummins you may need to know the whole system context to know what to optimise

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#Quarkus @holly_cummins “Nines don’t matter if your users aren’t happy.” – Charity Majors

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#Quarkus @holly_cummins don’t forget the edges queueing theory helps us understand where the disasters happen

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#Quarkus @holly_cummins “When it comes to IT performance, amateurs look at averages. Professionals look at distributions.” – Avishai Ish-Shalom

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#Quarkus @holly_cummins slow performance can turn into big cloud bills make cloud costs visible to engineers

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#Quarkus @holly_cummins ok, but you promised bears

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#Quarkus @holly_cummins if you leave the TV on when you’re not using it, you’re a polar bear murderer

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#Quarkus @holly_cummins there is a moral imperative to avoid waste

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#Quarkus @holly_cummins there is a moral imperative to avoid waste electricity hardware

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#Quarkus @holly_cummins data centres use 1-2% of the world’s electricity

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#Quarkus @holly_cummins fewer devices longer lifetime

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#Quarkus @holly_cummins fewer devices longer lifetime higher efficiency

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#Quarkus @holly_cummins fewer devices longer lifetime higher efficiency lower footprint

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#Quarkus @holly_cummins fewer devices longer lifetime higher efficiency lower footprint more multitenancy

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#Quarkus @holly_cummins fewer devices longer lifetime higher efficiency lower footprint more multitenancy optimise for longevity

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#Quarkus @holly_cummins fewer devices longer lifetime higher efficiency lower footprint more multitenancy optimise for longevity the end of planned obsolescence?

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#Quarkus @holly_cummins sooo … you can optimise, and it can be fun measure, don’t guess only optimise what matters now for questions!