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⚡ Bolt: Cache colors.ColorMap() in StatusLine to avoid repeated allocations #74

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⚡ Bolt: Cache colors.ColorMap() in StatusLine to avoid repeated allocations #74

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3 changes: 3 additions & 0 deletions .jules/bolt.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
## 2024-04-29 - Cache Large Map Allocations at Instance Level
**Learning:** Returning a large `map[string]string` from a function like `colors.ColorMap()` on every plugin invocation creates significant repeated memory allocation overhead, particularly in parallel rendering operations like `StatusLine.Render()` which executes 5-10 times.
**Action:** Always cache large reference types (like maps) at the struct instance level (e.g. within `StatusLine`) during initialization to avoid redundant allocations in hot loops. Add fallback initialization `if sl.colorMap == nil` for backward compatibility with manual struct initialization in tests.
9 changes: 8 additions & 1 deletion internal/statusline/statusline.go
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Expand Up @@ -35,6 +35,7 @@ type StatusLine struct {
isIdle bool
bashPlugins []plugin.Plugin // Cached discovered bash plugins
bashPluginsOnce sync.Once
colorMap map[string]string // Cached color map to avoid allocations
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@gemini-code-assist gemini-code-assist Bot Apr 29, 2026

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high

To safely handle lazy initialization of colorMap in a concurrent environment, add a sync.Once field to the StatusLine struct. This is necessary because runPlugin is called from multiple goroutines in renderLine, and the current lazy initialization logic is not thread-safe.

	colorMap        map[string]string // Cached color map to avoid allocations
	colorMapOnce    sync.Once

}

// New creates a new StatusLine renderer
Expand All @@ -45,6 +46,7 @@ func New(input Input, cfg config.Config) *StatusLine {
pluginManager: plugin.NewManager(),
nativePlugins: plugins.NewRegistry(),
isIdle: checkIsIdle(input.SessionID),
colorMap: colors.ColorMap(),
}
}

Expand Down Expand Up @@ -612,6 +614,11 @@ func (sl *StatusLine) getConfigBool(key string, defVal bool) bool {
}

func (sl *StatusLine) runPlugin(name string) string {
// Initialize colorMap if nil (for tests that construct StatusLine manually)
if sl.colorMap == nil {
sl.colorMap = colors.ColorMap()
}
Comment on lines +618 to +620
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@gemini-code-assist gemini-code-assist Bot Apr 29, 2026

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high

This lazy initialization is subject to a data race. Since runPlugin is executed within parallel goroutines (via renderLine), multiple threads may attempt to check and initialize sl.colorMap simultaneously if the struct was manually initialized (a scenario explicitly mentioned in the PR description for tests). Using sl.colorMapOnce ensures that the initialization happens exactly once and is thread-safe.

Suggested change
if sl.colorMap == nil {
sl.colorMap = colors.ColorMap()
}
sl.colorMapOnce.Do(func() {
if sl.colorMap == nil {
sl.colorMap = colors.ColorMap()
}
})


// Build plugin input
input := plugin.Input{
Prism: plugin.PrismContext{
Expand All @@ -634,7 +641,7 @@ func (sl *StatusLine) runPlugin(name string) string {
ContextWindowSize: sl.input.Context.ContextWindow,
},
Config: sl.getPluginConfig(name),
Colors: colors.ColorMap(),
Colors: sl.colorMap,
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@gemini-code-assist gemini-code-assist Bot Apr 29, 2026

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medium

By caching and reusing sl.colorMap, the same map instance is now shared across all plugin invocations. While this reduces allocations, it means that if any native plugin modifies the Colors map, it will affect other plugins and subsequent renders. Ensure that all native plugins treat the Colors map as read-only, or consider providing a copy if mutation is a risk.

}

// Try native plugin first (much faster - no subprocess)
Expand Down
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