Revise backpressure examples in streams documentation

[baskakov]

Discussed here: https://stackoverflow.com/questions/79821132/node-js-back-pressure-documentation-whats-the-relevance-of-their-example Original backpressure example contains following oddities: 1) Incorrect zip example 2) Incorrect assumption that zip console command loads full file into memory. Updated examples to demonstrate file compression using Node.js streams with backpressure handling.

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Project	Deployment	Actions	Updated (UTC)
nodejs-learn	Ready	Preview	Jun 14, 2026 9:26am

[cursor]

PR Summary

Low Risk
Documentation-only edits to examples and explanatory text; no runtime or API changes.

Overview
Replaces the opening backpressure demo in backpressuring-in-streams.md so it no longer contrasts a shell zip run with a Node gzip pipeline.

The section now walks through three Node-only steps on the same ~9 GB file: readFileSync + gzipSync (buffer/heap limits), manual data handlers that ignore write() backpressure (unbounded buffers / OOM), then inp.pipe(gzip).pipe(out) with prose on pause, false from write(), and 'drain'.

The removed narrative that compared a “corrupt” zip output to a successful stream decompress is gone; the existing pipe / pump / pipeline notes are unchanged.

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[github-actions]

👋 Codeowner Review Request

The following codeowners have been identified for the changed files:

Team reviewers: @nodejs/streams

Please review the changes when you have a chance. Thank you! 🙏

[Copilot]

Pull request overview

Note

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Updates the backpressure module to better illustrate memory/throughput implications of buffering vs streaming in Node.js compression examples.

Changes:

• Replaces the zip(1) example with fs.readFileSync + zlib.gzipSync examples (CJS + ESM).
• Adds an explicit “streams without backpressure” example plus an explanation of why it can OOM.
• Removes the prior note about comparing resulting archives.

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[avivkeller]

Suggested change

	const gzip = require('node:zlib').createGzip();
	const { createGzip } = require('node:zlib');
	const gzip = createGzip();

[avivkeller]

Suggested change

	Neither of two writes respects backpressure. Stage 1 keeps pushing into gzip even after gzip.write() returns false, and stage 2 keeps pushing into out even after out.write() returns false. Both internal buffers can grow without bound, so this is very prone to running out of memory. On a large compressible file both numbers climb fast and it heads for `JavaScript heap out of memory`.
	Neither of two writes respects backpressure. Stage 1 keeps pushing into gzip even after `gzip.write()` returns false, and stage 2 keeps pushing into out even after `out.write()` returns false. Both internal buffers can grow without bound, so this is very prone to running out of memory. On a large compressible file both numbers climb fast and it heads for `JavaScript heap out of memory`.

[avivkeller]

Suggested change

	To resolve this, we may use pipe, which pauses the read when write() returns false. When `gzip.write()` returns `false`, `pipe` calls `pause()` on the read stream, halting disk reads. Once gzip works through its backlog and the buffer empties, it emits a `'drain'` event, and `pipe` calls `resume()` to start reading again.
	To resolve this, we may use pipe, which pauses the read when `write()` returns false. When `gzip.write()` returns `false`, `pipe` calls `pause()` on the read stream, halting disk reads. Once gzip works through its backlog and the buffer empties, it emits a `'drain'` event, and `pipe` calls `resume()` to start reading again.