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stream: avoid pause with unpipe in buffered write

If a pipe is cleaned up (due to unpipe) during a write that
returned false, the source stream can get stuck in a paused state.

Fixes: #2323
PR-URL: #2325
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
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mscdex authored and jasnell committed Oct 11, 2015
1 parent 5479562 commit 7b9f78acb28ba6f6fa0f82ce70abcc9ab327212e
Showing with 51 additions and 3 deletions.
  1. +13 −3 lib/_stream_readable.js
  2. +38 −0 test/parallel/test-stream-pipe-cleanup-pause.js
@@ -497,6 +497,7 @@ Readable.prototype.pipe = function(dest, pipeOpts) {
var ondrain = pipeOnDrain(src);
dest.on('drain', ondrain);

var cleanedUp = false;
function cleanup() {
debug('cleanup');
// cleanup event handlers once the pipe is broken
@@ -509,6 +510,8 @@ Readable.prototype.pipe = function(dest, pipeOpts) {
src.removeListener('end', cleanup);
src.removeListener('data', ondata);

cleanedUp = true;

// if the reader is waiting for a drain event from this
// specific writer, then it would cause it to never start
// flowing again.
@@ -524,9 +527,16 @@ Readable.prototype.pipe = function(dest, pipeOpts) {
debug('ondata');
var ret = dest.write(chunk);
if (false === ret) {
debug('false write response, pause',
src._readableState.awaitDrain);
src._readableState.awaitDrain++;
// If the user unpiped during `dest.write()`, it is possible
// to get stuck in a permanently paused state if that write
// also returned false.
if (state.pipesCount === 1 &&
state.pipes[0] === dest &&
src.listenerCount('data') === 1 &&
!cleanedUp) {
debug('false write response, pause', src._readableState.awaitDrain);
src._readableState.awaitDrain++;
}
src.pause();
}
}
@@ -0,0 +1,38 @@
'use strict';
const common = require('../common');
const assert = require('assert');
const stream = require('stream');

const reader = new stream.Readable();
const writer1 = new stream.Writable();
const writer2 = new stream.Writable();

// 560000 is chosen here because it is larger than the (default) highWaterMark
// and will cause `.write()` to return false
// See: https://github.com/nodejs/node/issues/2323
const buffer = new Buffer(560000);

reader._read = function(n) {};

writer1._write = common.mustCall(function(chunk, encoding, cb) {
this.emit('chunk-received');
cb();
}, 1);
writer1.once('chunk-received', function() {
reader.unpipe(writer1);
reader.pipe(writer2);
reader.push(buffer);
setImmediate(function() {
reader.push(buffer);
setImmediate(function() {
reader.push(buffer);
});
});
});

writer2._write = common.mustCall(function(chunk, encoding, cb) {
cb();
}, 3);

reader.pipe(writer1);
reader.push(buffer);

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