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f624d3a00a
Seven commits from one week of load testing: one hang, two request-path correctness fixes, and four hot-path costs that only show up in production. ## Reliability **Bound every upstream call.** The litellm backend had no timeout at all, so a request the upstream never answered blocked its caller forever. Observed under load on 2026-08-07: four agent workers on ESTABLISHED connections for 36+ minutes while `/readyz` answered in 0.11s. No error, no retry, no log line — indistinguishable from slow work, which is the worst shape a failure can take. A float rather than an `httpx.Timeout`, deliberately: litellm expands a float across all four httpx phases, so on a streaming call it becomes the maximum gap *between chunks*, not a cap on total generation. A long answer streaming steadily is never cut off; a stalled one dies. Default 600s via `HEADROOM_UPSTREAM_TIMEOUT`; 0, negative, and junk fall back to the default rather than meaning "no timeout". **Keep the consistency re-count off the event loop.** It ran `tokenizer.count_messages` twice directly on the loop. Since Claude counting moved to a real BPE that is CPU-bound work stalling every other in-flight request — ~1s on a 2.3 MB body, with `/healthz` gaps tracking body size. Offloaded via `asyncio.to_thread` on the same tokenizer instance, so reported values are unchanged. (#2810) **Survive a re-parse MemoryError.** `MemoryError` is not a `ValueError`, so on 1M-context payloads the byte-faithful forwarder's verification re-parse escaped the handler and aborted an otherwise-fine request — 14 aborts across 8 days of reporter logs. (#2768) ## Performance All four are measured, not guessed. Each degrades with something a short benchmark does not vary: uptime, content shape, or process age. | fix | before | after | |---|---|---| | Cost-record walk per request (at 100k records) | 13.6 ms | bounded by model count | | JSON-block scan, JS-style object logs (1200 lines) | 4643 ms | 183 ms | | JSON-block scan, truncated JSONL | 3737 ms | 116 ms | | Lazy imports inside user requests | multi-second | paid at startup | | `count_text` (80% of local CPU) | — | memoised | Two worth calling out: - **The cost walk degrades with proxy *uptime*, not load.** A freshly started proxy pays ~0.01 ms; a month-old one pays 4–13 ms on every request, on the event loop, holding the metrics lock. Deliberately not a TTL cache over `stats()`: those values feed `check_budget()` when `--budget` is set, and a stale reading under-enforces the budget. The fix is to stop computing what the caller discards. - **The JSON-block memo is built only *after* a scan fails to balance.** That ordering is load-bearing, not an optimisation — caching from the start made pretty-printed JSON ~2x slower, since content that balances on the first scan has nothing to reuse and just pays the per-line dict traffic. Still a constant-factor fix, not an asymptotic one. ## Tests +1202 lines, 20 files. Each fix is pinned by a test that fails on the unmodified code: the re-count test asserts no `count_messages` pass runs with a live event loop in its thread; the re-parse test drives a `MemoryError` through the real request path and expects a 200; `totals()` equality with `stats()` is asserted across model counts, request volumes, and both pricing branches. The timeout test is structural rather than a mock — the failure mode is a dispatch path someone adds later without a guard, which mocking the existing four cannot catch. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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| .. | ||
| test_anthropic_buffered_timeout.py | ||
| test_anthropic_ccr_deferred_injection.py | ||
| test_anthropic_ccr_raise.py | ||
| test_anthropic_recount_and_reparse_safety.py | ||
| test_anthropic_streaming_ccr_retrieve.py | ||
| test_anthropic_upstream_header.py | ||
| test_background_compression.py | ||
| test_bedrock_passthrough.py | ||
| test_bedrock_sse_ping.py | ||
| test_cc_switch_reconciler.py | ||
| test_ccr_frozen_prefix_coupling.py | ||
| test_compression_failure_action.py | ||
| test_compression_timeout_config.py | ||
| test_compute_turn_id.py | ||
| test_gemini_savings_profile.py | ||
| test_header_safe_transforms.py | ||
| test_mcp_stats_aggregation.py | ||
| test_model_router.py | ||
| test_model_router_wiring.py | ||
| test_openai_backend_path.py | ||
| test_openai_chat_savings_profile.py | ||
| test_openai_responses_ccr.py | ||
| test_openai_stream_usage_option.py | ||
| test_openai_transport_path_prefix.py | ||
| test_openai_upstream_header.py | ||
| test_phase3_byte_identity.py | ||
| test_request_logger.py | ||
| test_settings_fresh_process_precedence.py | ||
| test_settings_store.py | ||
| test_transformations_feed.py | ||