[dev nexus 2024] a glance at the java performance toolbox

Speaker: Ana Maria Mihalceanu

@ammbra1508

For more, see the 2024 DevNexus Blog Table of Contents


What is performance

  • From user POV, how much work can do in a reasonable amount of time
  • From business, what is cost in computational resources needed to provide that user experience

Cloud

  • Practically unlmited resources
  • Reasonable cost

Container images

  • Tools to build container images – docker, jib, kaniko, buidah, etc
  • All started with a Dockerfile
  • Other tools arrived later to make easier

JLink

  • JRE stopped being included in Java 11
  • Can use jlink to include custom JRE with just modules need.
  • Can also omit man pages and header files.
  • Compress zip-9 offers the best compression.

Fine Tuning JVM Flags

  • Ergonomics docs – process for JVM/GC to tune performance measures
  • Tune min/max heap size with -Xms and -Xmx
  • Consider Java heap ratio

jcmd

  • Tracks native memory
  • Want available in container
  • Add jdk.jcmd module to application

Other commands/tools

  • Use jinfo to see what flags used in app
  • Helps when don’t know all flag names
  • Look for amount of memory reserved and amount used
  • Look for big values
  • JConsole – can see graph of memory use
  • jstat – garbage collection statistics
  • jmap – histogram of heap summary
  • Profiling with Java Flight Recorder – use when looking for something, not all the time. Need jdk.jfr module. Can specify how long to record.
  • Prometheus server – monitors/alerts on events
  • JFR Streaming – sends metrics to monitoring service

Sample app for testing at https://github.com/ammbra/performance-glance

My take

Good information and good demo. It was nice seeing the commands actually get used. Clear how to apply.

[dev nexus 2024] Table of Contents

This is DevNexus’ 20th anniversary!

Wednesday

Thursday

[uberconf 2023] intellij dojo

Dan Hinojosa

For more, see the table of contents


Uses https://github.com/dhinojosa/intellij-dojo-workshop

General

  • Help > Keyboard Shortcuts PDF
  • Goal: get away from mouse
  • I tried to note both windows and mac since I use both. I followed along on Mac live
  • Presentation assistant shows shortcuts used [I used this one]
  • Key Promoter X – reminds you to use plugin [I turned this off; it was super annoying]

New projects

  • Projects typically created outside the IDE so just have to open the project
  • Open new project (or recent projects)
  • Can setup to open from command line by typing “idea .” – Open toolbox (not in IntelliJ; helps with downloading > bolt > settings > tools – shows where command line)

Navigation

  • Command or alt 1 – project menu – start typing name of file to get straight to it. Arrows to go thru nav menu.
  • Command or alt 2 – bookmarks
  • shift escape – close window – ex if have bookmarks open.
  • Command or alt 3 – find window
  • Command or alt 4 – run window
  • Command or alt 5 – debug window
  • Command or alt 6 – problems window “six is to fix”
  • Command or alt 7 – structure window (outline of file)
  • Command or alt 9 – git log
  • Command or alt 0 – commit window
  • Command or alt e – recent files list
  • Command shift e – recent edit locations (within file)
  • Command or control shift F12 – maximize/restore editor

Action keys

  • Command or control shift A – all actions – shows shortcut next to it so can type name and review shortcut
  • control control – run anything within project. type “?” to see what the choice are. ex: run maven test quickly. Also shows recent commands
  • shift shift – search everywhere ex: files, options in ide, even has a calculator

Navigation

  • control (or Alt windows) right/left – didn’t work for me on mac; ctrl tab lets me see tabs and pressing it repeatedly switches between them
  • ctrl F4 (was command w on my machine)

Finding items

  • command o/Ctrl N – go to class (supposed to be o for mac, but n works for me)
  • command shift o/ctrl shift n – go to file
  • command option o/ctrl option n – go to symbol
  • command/ctrl b – go to declaration
  • command/ctrl alt b – go to implementation
  • option/alt f7 – find usages
  • command/ctrl f7 – find in file

TDD Sample

  • command/ctrl n – create new – then choose what want ex: Java class. do again within class and can create test method automatically
  • F2/shift F2 – switch between problems (ex: compiler error). If no errors, says no errors found
  • alt/option enter – context sensitive actions ex: fix error, refactor
  • command/ctrl shift t – toggle between test and code under test
  • ctrl t (mac) ctrl alt shift t (win) – refactor this menu
  • command l – go to line

Formatting

  • command option/control alt l – format all code
  • control alt/option o – organize imports

Selecting code blocks

  • option down/ctrl shift w increase code block selected – ex: line -> section of code -> method -> class
  • option up/ctrl w increase code block selected

Editing

  • command/ctrl backspace – delete line
  • command/ctrl d – duplicate line
  • command/ctrl x – cut line
  • command/ctrl c – copy line
  • command/ctrl v paste line
  • command/ctrl shift v – paste from history; still available even after pasted
  • command/ctrl t – surround block/selection – didn’t work for me on mac
  • command option t/ctrl shift t – surround with – ex: wrap with if/try/etc

Code completion

  • pvsm – generate main method
  • postfix – write. sout or .var or the like at end of line if forgot something at beginning of line and fixes. Can add own with live templates
  • ctrl space – autocomplete
  • ctrl option/alt space – inaccessible members autocomplete; will import at same time
  • ctrl shift space – type sensitive complete – filter autocomplete based on the desired type
  • command/ctrl shift enter – complete statement – ex: add { for if statement
  • command/ctrl p – parameter info – click method and get pop up with the parameters for all overloads. Works when writing code or on filled in code
  • ctrl shift p – type info – useful on a stream to see return type. If ambiguous have to chose which expression from a list first

Moving

  • Command/ctrl shift up or down – move code up or down compared to other code

Docs

  • Ctrl Q – windows, Ctrl J – mac – pop up for docs
  • ctrl shift i win, command y – mac – pop up with source code/implementation. use right/left if multiple matches (ex: levels in hierarchy)
  • alt q windows, ctrl shift q mac – pop up with method name, press again for class. useful in long legacy code

Run/Debug

  • Contextually – main methods, tests , folder of tests etc
  • If create file named http, will run it. Uses specified format to specify get/post, content type, etc – https://www.jetbrains.com/help/idea/http-client-in-product-code-editor.html. Good if don’t need credentials
  • ctrl shift F10 win, ctrl shirt r mac – First time, run and mark context configuration. Like staking a claim
  • shift F10 win, ctrl r mac- run last config
  • alt shift f10 win, ctrl option r mac – mark context
  • Replace d with r for debug versions
  • In debugger, trace current stream chain lets you see each step of a stream and what is there. (click three dots in debugger to see it). Choose flat mode to see everything on one screen

Refactoring

  • ctrl t (mac) ctrl alt shift t (win) – refactor this menu – this one includes all the other refactorings. Including obscure ones like changing a method return type
  • F5 – copy item
  • F6 – move item
  • shift F6 – rename globally
  • command/alt delete – safe delete
  • ctrl alt n – inline
  • command option/ctrl alt m – extract method
  • command option/ctrl alt v – extract variable
  • command option/ctrl alt f – extract field
  • command option/ctrl alt c – extract constant
  • command option/ctrl alt p – extract parameter

Multicursor

  • shift command 8/alt shift insert win – start column selection mode.
  • hold shift down and get multiple cursors at that column
  • alt/option shift click – start multicursor mode – each click gives you a cursor
  • ctrl g mac, alt j windows – next instance of word giving you a cursor for each (select method/class/etc want to match first)
  • ctrl command g mac, alt shift j win – all instances of word giving cursor for each

HTML/XML editing

Version Control

  • Command/Ctrl 0 – changes window
  • Command/Ctrl K – commit
  • Command/Ctrl t – update project
  • command/ctrl shift k – push
  • ctrl v – mac, alt ` windows – version control quick help

Random stuff

  • If reference a closure variable (ex: effectively final variable used in a lambda), variable appears in purple.
  • Presentation mode – don’t need to mess with font manually when present
  • File and Code templates – for commonly used code

Side note

Chrome has a built in QR code generator – share the link and QR is an option

My take

It was good to get practice and learn more shortcuts. Also learned I had my keymap set to mac classic (that explains why some expected shortcuts hadn’t worked; fixed it). I like the windows/mac contrasts. Felt less magical seeing it presented together. (I use both).. Good mix of hands on and watching.