asmhatreandClaude Opus 5
a065696478
Companion code for "Deploying Spring Boot 4 on Kubernetes: Probes, Graceful Shutdown, Limits and JVM Ergonomics". A dependency outage under three probe-group setups, a rolling restart under load four ways (three runs each), the JVM's ergonomic choices for nine pod shapes, one GC-heavy load under five CPU limits with throttling counters, and an HPA driven by a Micrometer gauge through prometheus-adapter. Measured on k3s v1.36.4. Co-Authored-By: Claude Opus 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01C3TETMrqVUWeFkNtz3Jbo3
43 lines
2.2 KiB
Bash
43 lines
2.2 KiB
Bash
#!/usr/bin/env bash
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# What the JVM decides from the pod's resources, with no JVM flags at all.
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# -> docs/output/jvm-ergonomics.txt
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set -uo pipefail
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source "$(dirname "$0")/env.sh"
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# cpu.limit | cpu.request | mem.request | mem.limit. Requests are deliberately small and constant:
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# the JVM ignores them (JDK-8281181 removed CPU shares from the calculation in JDK 19), and small
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# requests let every case schedule on a 2-CPU node.
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CASES=(
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"none|100m|256Mi|2Gi"
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"500m|100m|256Mi|512Mi"
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"1|100m|256Mi|1Gi"
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"1|100m|256Mi|2Gi"
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"1500m|100m|256Mi|2Gi"
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"2|100m|256Mi|1Gi"
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"2|100m|256Mi|1700Mi"
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"2|100m|256Mi|1800Mi"
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"2|100m|256Mi|4Gi"
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)
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flag() { grep -E "^ *[a-z_]+ +$1 " <<< "$2" | awk '{print $4}'; }
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{
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echo "# JVM ergonomics per pod resources. Image: $IMAGE, no JVM options. Node: $(nproc) CPUs."
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echo "# cgroup v$( [ -f /sys/fs/cgroup/cgroup.controllers ] && echo 2 || echo 1 ) node; see docs/03-jvm-ergonomics.md for the v2 equivalents."
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echo
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printf '%-7s %-7s %-7s %-7s | %-5s %-10s %9s %6s %6s %6s\n' "cpu.req" "cpu.lim" "mem.req" "mem.lim" "CPUs" "GC" "MaxHeap" "PGCThr" "CGCThr" "JITThr"
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i=0
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for c in "${CASES[@]}"; do
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IFS='|' read -r cl cr mr ml <<< "$c"
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if [ "$cl" = none ]; then res="{requests: {cpu: $cr, memory: $mr}, limits: {memory: $ml}}"
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else res="{requests: {cpu: $cr, memory: $mr}, limits: {cpu: $cl, memory: $ml}}"; fi
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out=$(oneoff "erg-$i" "$res" java -XX:+PrintFlagsFinal -version 2>&1)
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gc=SerialGC; [ "$(flag UseG1GC "$out")" = true ] && gc=G1GC; [ "$(flag UseParallelGC "$out")" = true ] && gc=ParallelGC
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cpus=$(oneoff "erg-$i" "$res" java -XshowSettings:system -version 2>&1 | grep -i 'Effective CPU Count' | awk -F: '{gsub(/ /,"",$2); print $2}')
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heap=$(( $(flag MaxHeapSize "$out") / 1024 / 1024 ))
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printf '%-7s %-7s %-7s %-7s | %-5s %-10s %8sM %6s %6s %6s\n' "$cr" "$cl" "$mr" "$ml" "$cpus" "$gc" "$heap" \
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"$(flag ParallelGCThreads "$out")" "$(flag ConcGCThreads "$out")" "$(flag CICompilerCount "$out")"
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i=$((i+1))
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done
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echo
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echo "# java -XshowSettings:system for the 1500m case:"
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oneoff erg-show "{requests: {cpu: 100m, memory: 256Mi}, limits: {cpu: 1500m, memory: 2Gi}}" java -XshowSettings:system -version 2>&1 | grep -vE '^(openjdk|OpenJDK)'
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} | tee "$OUT/jvm-ergonomics.txt"
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