[Yasiru Kassapa (yasiruk)]

First and foremost thank you for the great product. I have been using Azurite for the last three years and it has made local development a breeze.

Why

Ran into HTTP 500 errors after a while when a client performed a large number of HTTP range requests on a single blob.
Following is an excerpt of the log related to the AggregateError: EMFILE: too many open files error:

error: ErrorMiddleware: Received an error, fill error information to HTTP response
error: ErrorMiddleware: ErrorName=AggregateError ErrorMessage=EMFILE: too many open files, open '/tmp/azurite/__blobstorage__/07282f07-dc04-463f-86dc-deca4665780f' ErrorStack="AggregateError: EMFILE: too many open files, open '...'
    at ReadStream.<anonymous> (node:internal/streams/destroy:81:22)
    ...
    at onConstruct (node:internal/streams/destroy:291:14)
error: ErrorMiddleware: Set HTTP code: 500
info: EndMiddleware: End response. TotalTimeInMS=5 StatusCode=500 ... "content-length":"1038090240","content-range":"bytes 35651584-1073741823/1073741824", ...

Turned out the issue was already reported in #2804

How to reproduce the error

You can use this docker image (which is based on azurite:3.37.0) to reproduce the error easily.

# syntax=docker/dockerfile:1
# Downloads that the client closes early leak file handles in Azurite.
#   docker build -t azurite-leak . && docker run --rm azurite-leak
ARG AZURITE_IMAGE=mcr.microsoft.com/azure-storage/azurite:3.37.0
FROM ${AZURITE_IMAGE}

COPY <<'EOF' /repro.mjs
import { createHmac } from "node:crypto";
import { readFileSync, readdirSync } from "node:fs";
import http from "node:http";

// Azurite's well-known development account, and an account SAS for it.
const account = "devstoreaccount1";
const key = "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==";
const expiry = new Date(Date.now() + 3600_000).toISOString().slice(0, 19) + "Z";
const stringToSign = [account, "rwc", "b", "co", "", expiry, "", "", "2021-08-06", "", ""].join("\n");
const sig = createHmac("sha256", Buffer.from(key, "base64")).update(stringToSign).digest("base64");
const sas = new URLSearchParams({ sv: "2021-08-06", ss: "b", srt: "co", sp: "rwc", se: expiry, sig });
const url = (path, query = "") => `http://127.0.0.1:10000/${account}/repro${path}?${query}&${sas}`;

const put = async (target, body) => {
  const res = await fetch(target, { method: "PUT", body });
  if (!res.ok) throw new Error(`PUT ${res.status}: ${await res.text()}`);
};
const openFiles = () => readdirSync(`/proc/${process.env.AZURITE_PID}/fd`).length;

// A 64 MB blob of 1 MB blocks.
for (let retry = 0; ; retry++) {
  try { await put(url("", "restype=container")); break; }
  catch (error) { if (retry > 50) throw error; await new Promise((r) => setTimeout(r, 200)); }
}
const blockIds = [];
for (let i = 0; i < 64; i++) {
  const blockId = Buffer.from(String(i).padStart(6, "0")).toString("base64");
  await put(url("/blob", `comp=block&blockid=${encodeURIComponent(blockId)}`), Buffer.alloc(1024 * 1024));
  blockIds.push(blockId);
}
await put(url("/blob", "comp=blocklist"),
  `<BlockList>${blockIds.map((id) => `<Latest>${id}</Latest>`).join("")}</BlockList>`);

// Like ffmpeg seeking: request "bytes=0-", read the first chunk, and close the connection.
const abortedDownload = () => new Promise((resolve) => {
  let status;
  const req = http.get(url("/blob"), { headers: { Range: "bytes=0-" } }, (res) => {
    status = res.statusCode;
    res.once("data", () => req.destroy());
  });
  req.on("error", () => {});
  req.on("close", () => resolve(status));
});

console.log(`Azurite open files at the start: ${openFiles()}`);
for (let i = 1; i <= 200; i++) {
  const status = await abortedDownload();
  if (i % 20 === 0 || status !== 206) console.log(`Request ${i}: ${status}, Azurite open files: ${openFiles()}`);
  if (status === 500) {
    const errors = readFileSync("/tmp/debug.log", "utf8").split("\n").filter((line) => line.includes("ErrorMessage="));
    console.log(`Azurite ran out of file handles. Its debug log says:\n${errors[0].slice(0, 400)}`);
    process.exit(1);
  }
}
console.log("No 500 after 200 aborted downloads.");
EOF

# A low open file limit, so the 500 shows after a few requests. Azurite prints
# its access log, and writes the errors to its debug log.
ENTRYPOINT ["sh", "-c", "ulimit -n 1024; azurite-blob --location /tmp/azurite --debug /tmp/debug.log & AZURITE_PID=$! exec node /repro.mjs"]

[Copilot]

🟢 Approval recommended

The cleanup behavior is consistently implemented and covered by focused cross-service and HTTP regression tests.

0 open findings

What changed in this PR

Fixes leaked extent file descriptors by destroying response bodies when clients disconnect.

Changes:

• Adds cleanup across Blob, Queue, and Table serializers.
• Handles late extent-stream errors after cancellation.
• Adds serializer, persistence, and HTTP regression tests.

1. Impact analysis

   • Package: Azurite
   • Version change: None
   • Usage: Streamed storage responses
   • Impact and risk: Prevents EMFILE failures; low residual risk.

2. Build and conflict resolution

   • Commands run: None
   • Issues found: None
   • Result: Static review completed.

3. Tests

   • Tests added or updated: Serializer, FSExtentStore, and Blob disconnect tests
   • Coverage: All serializers plus Loki and SQL Blob paths
   • Result: Appropriate regression coverage.

4. Test suite

   • Commands run: None
   • Passing: Not independently verified
   • Pending or failing: CI validation pending.

5. Changelog

   • Entry added: Yes
   • Location: Upcoming release, General section

6. PR comments

   • Threads reviewed: Issue #2804 requirements
   • Actions taken: Reviewed all changed files
   • Unresolved items: None

7. Self-rating

   • Score: 9/10
   • Reasoning: Complete static review with focused cross-service and persistence analysis.

8. Iteration

   • Improvements made after self-review: Verified middleware lifecycle, response adapters, and test inclusion.

9. Summary

   • Why the update matters: Releases file descriptors after aborted downloads.
   • Risk if not applied: Repeated disconnects can exhaust file handles.
   • Final status: Ready for approval.

File	Description
src/​blob/​generated/​utils/​serializer.ts	Cleans up aborted Blob response bodies.
src/​queue/​generated/​utils/​serializer.ts	Adds equivalent Queue cleanup.
src/​table/​generated/​utils/​serializer.ts	Adds equivalent Table cleanup.
src/​common/​persistence/​FSExtentStore.ts	Handles errors from discarded late streams.
tests/​common/​serializer.test.ts	Tests cancellation across all serializers.
tests/​blob/​fsStore.test.ts	Tests late extent errors after cancellation.
tests/​blob/​apis/​blob.test.ts	Tests HTTP client disconnect scenarios.
ChangeLog.md	Documents the user-visible fix.

🧠 Review effort: Balanced

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[Yasiru Kassapa (yasiruk)]

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[Copilot]

🟢 Approval recommended

No active review issues remain for the client-disconnect cleanup changes, although validation commands were not run.

No open issues 🎉

_{Review effort: Balanced}

[Copilot]

🟢 Approval recommended

No active review issues remain for the disconnect-cleanup changes, though tests and builds were not run.

No open issues 🎉

_{Review effort: Max}