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Thursday, April 16, 2026
- deebofor some reason assumed yourkit snapshots would include jmx data, but no
- deeboany good options for recording and graphing micrometer data locally?, hopefully without running an open/elasticsearch cluster + grafana etc
- ParaI run Jaeger tracing through container :D
- ParaI'd wager depends on what you want out from the system.
- ParaI also always print trace/span id:s to each log row, general ideology being that as I have these systems, I've made them always available and linked across everything to let myself be lazy.
- ParaEven the REST API endpoints return those id:s so I can use browser dev tools to spy on what's going on.
- ParaWhat else...IDEA has actuator based live stats for service, that works as well.
- Parahttps://www.jetbrains.com/help/idea/spring-support-tutorial.html#actuator
- javabotPara's title: "Tutorial: Explore Spring support features | IntelliJ IDEA Documentation"
- ParaWhat I'm trying to say - it depends :)
- deeboi'm starting yourkit agent on startup in a docker swarm environment, doing a rolling upgrade to simulate a deployment and then after a few minutes i bring the system down and the agent writes snapshots to disk
- deebobut yourkit snapshots can't be filtered by time, and i can't correlate e.g. jdbc onnection acquisition times
- deeboat this point i'd need more of an apm than cpu profiling
- deebomaybe i'll jhust have to deploy to our real env to get a real apm agents stats, just slows the roundtrips for testing by 10x, really annoying
- deeboor i have to programmatically start the yourkit profiling so i get exactly what i want in the snapshot
- deebodidn't notice until now but yourkit agent has a periodic snapshot feature, so could capture 1 minute slices to find a good set of data, but i added a hook on startup (when ready for traffic) to profile for 90 seconds, save snapshot and stop profiling
- deebohope this gives me something useful
- dmlloydmaybe you want JFR, or maybe look into async profiler
- dreamrealSDL has decided to disallow AI use in the project, which I find interesting
- dreamrealI understand it, but I think that's a bad response to a real problem
- deeboyeah have to check jfr at some point
- deebobut i think i finally found the issue, hikaricp creates new connections sequentally blocking, so if you have a buttload of traffic suddenly coming in, everything takes ages, but there's a switch to have it block init until minimum-idle connections are created
- dreamrealHow long is it taking to open a new connection?
- deebohave to measure at some point, but on a 1cpu 2gb node that does 99.95% io bound work, all that traffic and initializations seem to be slowing it down, and is the onyl consistent blip in profiling
- deebo99% response times go from 20ms to 1000ms for ~15sec
- deeboduring a rolling node-by-node deploy
- dreamrealto *connect to a database*? Yikes.
- deeboyourkits tracing has way too much overhead, and in sampling mode it gets really confused by virtual threads
- dreamrealhttps://bytecode.news/posts/2026/04/performance-whack-a-mole
- javabotdreamreal's title: "Performance Whack-a-Mole | bytecode.news"
- dreamrealThe guy that's about used JFR and JMC for virtual threads
- deeboyeah have to test jfr, and complain to yourkit
- deebojfr is hella confusing compared to yourkit, but have to look deeper into the method timing/profiling stuff, but execution sampling is useless in an io bound app, most cpu used was a ConcurrentHashMap at 0.8% that something uses for caching
- dreamrealhttps://bytecode.news/posts/2026/04/pilot-0-1-0-maven-gets-an-interactive-console
- javabotdreamreal's title: "Pilot 0.1.0: Maven Gets an Interactive Console | bytecode.news"
- ParaThe link's broken, missing .com and scheme
- Parato github
- dreamrealdadgummit
- dreamrealobsidian's drafting process mangles urls and I copied them poorly
- dreamrealfixed, thank you
- dreamrealPara: ++
- nevetPara now has karma of 2.