FDN-4261: switch to Shenandoah GC

[nicolagi]

Summary

• Switch JVM garbage collector from G1GC to ShenandoahGC for lower pause times (dependency-api and dependency-www)
• Bump generic-charts to v2.0.10 which supports the garbageCollector knob

Test plan

• Verify ArgoCD diff shows ShenandoahGC in JAVA_OPTS for both services
• Monitor GC pause times after deploy

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Updated chart dependency versions to v2.0.12 across deployment configurations
  • Added Shenandoah garbage collector option to JVM configuration

[flow-tech]

Argo diff output for dependency-www:

===== /Service production/dependency-www ======
11c11
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== apps/Deployment production/dependency-www-live ======
16c16
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60
552,553c552,554
<           value: -Xms2100m -Xmx2100m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/dumps/oom.bin
<             -XX:+UseG1GC -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
---
>           value: -Xms2100m -Xmx2100m -XX:+UseShenandoahGC -XX:+HeapDumpOnOutOfMemoryError
>             -XX:HeapDumpPath=/dumps/oom.bin -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
>             -Xlog:gc*:stdout:time,uptime,level,tags

===== datadoghq.com/DatadogMonitor datadog/dependency-www-errorrate ======
145d144
<   - generated:kubernetes

===== networking.istio.io/Gateway production/dependency-www-flow-io ======
17c17
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== networking.istio.io/VirtualService production/dependency-www-live ======
12c12
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

[flow-tech]

Argo diff output for dependency-api:

===== /Service production/dependency ======
11c11
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== apps/Deployment production/dependency-api-live ======
16c16
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60
552,553c552,554
<           value: -Xms2100m -Xmx2100m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/dumps/oom.bin
<             -XX:+UseG1GC -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
---
>           value: -Xms2100m -Xmx2100m -XX:+UseShenandoahGC -XX:+HeapDumpOnOutOfMemoryError
>             -XX:HeapDumpPath=/dumps/oom.bin -XX:+UseStringDeduplication -XX:FlightRecorderOptions=stackdepth=256
>             -Xlog:gc*:stdout:time,uptime,level,tags

===== datadoghq.com/DatadogMonitor datadog/dependency-api-errorrate ======
145d144
<   - generated:kubernetes

===== networking.istio.io/Gateway production/dependency-flow-io ======
17c17
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

===== networking.istio.io/VirtualService production/dependency-api-live ======
12c12
<     helm.sh/chart: flow-generic-1.6.59
---
>     helm.sh/chart: flow-generic-1.6.60

[coderabbitai]

📝 Walkthrough

Walkthrough

Updates two deployment configurations with chart version bump from v2.0.7 to v2.0.12 and adds ShenandoahGC garbage collector option to JVM configuration for both dependency-api and dependency-www services.

Changes

Cohort / File(s)	Summary
Chart Version Updates deploy/dependency-api/app.yaml, deploy/dependency-www/app.yaml	Updates Argo CD Application manifests to reference chart version v2.0.12 instead of v2.0.7.
JVM Garbage Collector Configuration deploy/dependency-api/values.yaml, deploy/dependency-www/values.yaml	Adds ShenandoahGC garbage collector option to jvmOpts configuration for both services.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'FDN-4261: switch to Shenandoah GC' directly and clearly summarizes the main change—switching from G1GC to ShenandoahGC for the JVM garbage collector across two services (dependency-api and dependency-www).
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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