gnodet opened a new pull request, #24349:
URL: https://github.com/apache/camel/pull/24349
## Summary
_Claude Code on behalf of Guillaume Nodet_
Fixes `ConcurrentModificationException` in TUI `MemoryTab.renderSparkline()`
caused by a race condition between the background data-refresh thread and the
UI render thread.
**Root cause**: `MetricsCollector` stores history data as `LinkedList`
values inside `ConcurrentHashMap` maps. The background refresh thread mutates
these lists in place (`.add()`, `.remove(0)`), while the UI render thread
iterates them via `.stream()` and `.get(i)`. `ConcurrentHashMap` protects the
map itself but not the individual `LinkedList` values.
**Fix**: Use copy-on-write semantics in `MetricsCollector` — instead of
mutating history lists in place, create a new copy, modify it, and atomically
swap it into the map via `ConcurrentHashMap.compute()`. Readers always iterate
an unmodified list snapshot. This fixes **all** affected tabs at once
(MemoryTab, OverviewTab, EndpointsTab, CircuitBreakerTab).
- Introduce `addToHistory()` helper that encapsulates the copy-on-write
pattern
- Refactor all 8 history update sites in `MetricsCollector` to use it
- Add concurrency regression tests exercising concurrent read/write
**Stack trace that was observed:**
```
java.util.ConcurrentModificationException
at
java.base/java.util.LinkedList$LLSpliterator.forEachRemaining(LinkedList.java:1254)
at
java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:570)
...
at
org.apache.camel.dsl.jbang.core.commands.tui.MemoryTab.renderSparkline(MemoryTab.java:244)
at
org.apache.camel.dsl.jbang.core.commands.tui.MemoryTab.render(MemoryTab.java:116)
```
## Test plan
- [x] New `MetricsCollectorConcurrencyTest` with 2 tests exercising
concurrent read/write on heap and throughput history maps
- [x] All 469 existing TUI tests pass
- [ ] Manual verification: run `camel monitor` with a live integration and
navigate to the Memory tab
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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