LangChain / RAG / Vector DBs · 课时

处理并发与速率限制

通过异步调用、批处理、重试和反压，让生产环境中的 RAG 服务在负载下仍保持响应。

第 4 / 4 课13 个步骤

处理并发与速率限制 是 CoddyKit 上的免费 LangChain / RAG / Vector DBs 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 LangChain / RAG / Vector DBs 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 LangChain / RAG / Vector DBs 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Load in Production

A live RAG service faces many simultaneous requests, each making embedding and LLM calls. Without care you hit rate limits, time out, or exhaust memory.

Synchronous Bottleneck

Blocking on each API call serializes work. While one request waits on the LLM, the server cannot serve others, wasting capacity.

Async I/O

Async lets a single worker handle many in-flight calls. While awaiting one response, the event loop serves other requests.

import asyncio

async def answer(q):
    docs = await retriever.ainvoke(q)
    return await chain.ainvoke({"q": q, "docs": docs})

results = asyncio.run(asyncio.gather(*[answer(q) for q in queries]))

Batching Embeddings

Embedding APIs are far cheaper and faster per item when you send many texts in one request. Batch chunks instead of calling once per chunk.

vectors = embeddings.embed_documents(batch)  # one call, many texts

Respecting Rate Limits

Providers cap requests and tokens per minute. A limiter throttles outgoing calls so you stay under the cap and avoid 429 errors.

import asyncio

sem = asyncio.Semaphore(10)  # max 10 concurrent calls

async def limited(q):
    async with sem:
        return await answer(q)

Retry with Backoff

Transient errors and 429s should be retried with exponential backoff and jitter, not hammered immediately.

import time, random

def call_with_retry(fn, tries=5):
    for i in range(tries):
        try:
            return fn()
        except RateLimitError:
            time.sleep((2 ** i) + random.random())
    raise RuntimeError("exhausted retries")

Idempotency on Retry

Retries can duplicate side effects. Make write operations idempotent using keys or upserts so a repeated call is harmless.

Backpressure

When the queue grows faster than you can serve it, apply backpressure: reject or shed new requests early rather than letting latency balloon for everyone.

Connection Pooling

Reuse HTTP connections and database clients across requests. Creating a new client per request wastes time on handshakes and can exhaust file descriptors.

Caching Hot Queries

Many users ask the same things. Cache embeddings and final answers for frequent queries to cut both latency and API cost dramatically.

key = hashlib.sha256(query.encode()).hexdigest()
if key in cache:
    return cache[key]
ans = expensive_rag(query)
cache[key] = ans

Putting It Together

Combine async handling, a concurrency semaphore, batched embeddings, retries with backoff, and caching. The service stays fast and stable as traffic scales.

Quick Check

Test your understanding of scaling RAG.

在交互式课程中回答

Recap

You learned to handle production load:

Async for concurrent in-flight calls
Batch embeddings; pool connections
Throttle with a limiter; retry with backoff
Apply backpressure and cache hot queries

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常见问题解答

「处理并发与速率限制」课时是免费的吗？

是的 — 「处理并发与速率限制」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 LangChain / RAG / Vector DBs 课程的其余内容，请升级到 CoddyKit PRO。 LangChain / RAG / Vector DBs 课程共包含 4 节课。

「处理并发与速率限制」这节课中我会学到什么？

通过异步调用、批处理、重试和反压，让生产环境中的 RAG 服务在负载下仍保持响应。你通过在浏览器中直接运行的动手代码来练习 LangChain / RAG / Vector DBs，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 LangChain / RAG / Vector DBs 需要有经验吗？

无需任何先前经验。CoddyKit 上的 LangChain / RAG / Vector DBs 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「处理并发与速率限制」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 LangChain / RAG / Vector DBs 课中编写并运行代码吗？

能。每节 LangChain / RAG / Vector DBs 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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