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⚡ perf(anthropic): pre-allocate slice capacity in assistantMessageParam#38

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matdev83 merged 1 commit into
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fix/anthropic-messages-invoke-allocation-4428547483559643442
Jun 29, 2026
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⚡ perf(anthropic): pre-allocate slice capacity in assistantMessageParam#38
matdev83 merged 1 commit into
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fix/anthropic-messages-invoke-allocation-4428547483559643442

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💡 What:
Pre-allocated the blocks slice capacity based on the length of m.Parts in assistantMessageParam within internal/plugins/backends/protocols/anthropicmessages/invoke.go.

🎯 Why:
When iterating over m.Parts and conditionally appending items to an uninitialized slice, the Go runtime might reallocate the underlying array multiple times as the length grows. Pre-allocating the capacity avoids these reallocations, saving CPU cycles and reducing memory allocations.

📊 Measured Improvement:
Before the optimization:

BenchmarkAssistantMessageParam-4        574483          2009 ns/op        2992 B/op          9 allocs/op

After the optimization:

BenchmarkAssistantMessageParam-4       1000000          1042 ns/op        1408 B/op          6 allocs/op
  • Execution time reduced from ~2009 ns/op to ~1042 ns/op (nearly a ~48% improvement).
  • Allocations reduced from 9 allocs/op to 6 allocs/op.
  • Memory allocated per operation reduced from 2992 B/op to 1408 B/op.

PR created automatically by Jules for task 4428547483559643442 started by @matdev83

Pre-allocate the `blocks` slice in `assistantMessageParam` with `make([]anthropic.ContentBlockParamUnion, 0, len(m.Parts))` to prevent multiple memory reallocations during `append` operations.

Co-authored-by: matdev83 <211248003+matdev83@users.noreply.github.com>
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  • internal/plugins/backends/protocols/anthropicmessages/invoke.go

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@matdev83 matdev83 merged commit a0be8ac into main Jun 29, 2026
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@matdev83 matdev83 deleted the fix/anthropic-messages-invoke-allocation-4428547483559643442 branch June 29, 2026 12:48
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