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fix: should not destroy streams #612

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dead-horse
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@dead-horse dead-horse commented Dec 2, 2015

use black-hole-stream to make sure stream's data has been read.

since user may set this.body to a http IncomingMessage, if we destroy this stream, it will destroy the http socket that make keep-alive failed, and may affect other http requests reusing this socket.
I think maybe we shouldn't destroy streams, only need to insure streams' data will be read and don't leak.

},
"engines": {
"node": ">= 0.12.0",
"iojs": ">= 1.0.0"
"node": ">= 0.12.0"

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node >= 4

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@dead-horse dead-horse Dec 2, 2015

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can we drop the support of node < 4 in koa@1 ? /cc @tj @jonathanong

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oh, master is v1.

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this should be its own pull request

@dead-horse dead-horse force-pushed the fix-destroy-everty-stream branch 2 times, most recently from 0da33f7 to 42382b4 Compare Dec 2, 2015
@dead-horse dead-horse force-pushed the fix-destroy-everty-stream branch from 42382b4 to 65f13fb Compare Dec 2, 2015
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@dead-horse dead-horse commented Dec 3, 2015

ping @jonathanong @fengmk2

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@fengmk2 fengmk2 commented Dec 4, 2015

LGTM

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this should be its own pull request

@dead-horse dead-horse force-pushed the fix-destroy-everty-stream branch from 65f13fb to bbf850b Compare Dec 4, 2015
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@dead-horse dead-horse commented Dec 4, 2015

@juliangruber all fixed

@dead-horse dead-horse force-pushed the fix-destroy-everty-stream branch from bbf850b to 078cac0 Compare Dec 4, 2015
var app = koa();
let stream1 = fs.createReadStream(__filename);
let stream2 = fs.createReadStream(__filename);
stream1.once('end', done);
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i don't understand why this one would end as well? it's never read from

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@dead-horse dead-horse Dec 4, 2015

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we'll destroy(consume) all stream's that set to this.body here https://github.com/koajs/koa/pull/612/files#diff-d86a59ede7d999db4b7bc43cb25a1c11R166

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@juliangruber juliangruber commented Dec 4, 2015

hmmm, this seems more like an edge case to me. are there other cases that would benefit from this change?

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@dead-horse dead-horse commented Dec 4, 2015

The most serious problem now is http keepalive sockets will be destroyed, and we must fix this issue. Not sure any other side effect if we destroy the streams.

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@juliangruber juliangruber commented Dec 4, 2015

are you sure destroying a http stream will affect other requests on the same socket? sounds more like a node bug to me

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@dead-horse dead-horse commented Dec 4, 2015

If you destroy an IncommingMessage, it will destroy the socket behind: https://github.com/nodejs/node/blob/master/lib/_http_incoming.js#L92

That will affect other IncommingMessage's that reusing the same socket and will cause socket hang up error. This is reported in ali-sdk/ali-oss#40 (sorry this issue is in chinese).

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@dead-horse dead-horse commented Dec 5, 2015

any suggestions? I'll merge this PR if no response in the next day. :)

@dead-horse dead-horse self-assigned this Dec 5, 2015
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@juliangruber juliangruber commented Dec 5, 2015

Hey man, no need to put a deadline on it. If you need it urgently use a fork or find a userland solution.

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@dead-horse dead-horse commented Dec 6, 2015

I think this is just a bug fix. so if anyone doubt this patch, I'll leave it here and fix in our own framework for now. :)

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@juliangruber juliangruber commented Dec 6, 2015

this patch fails if the body stream is endless, like for example:

this.body = fs.createReadStream('/dev/urandom');

or more real-worldy

this.body = serverSentEvents(createUpdateStream());

in the cases above it's required to destroy the stream.

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@juliangruber juliangruber commented Dec 6, 2015

and trying to read it all out will never finish

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@dead-horse dead-horse commented Dec 6, 2015

although i don't think pipe an endless stream to response meaningful. but maybe there is a solution has less impact. detect the stream in destroy and don't destroy IncommingMessage(a breaking change in destroy).

use black-hole-stream to make sure stream's data has been read
@dead-horse dead-horse force-pushed the fix-destroy-everty-stream branch from a949d79 to d9c1ea3 Compare Dec 9, 2015
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@dead-horse dead-horse commented Dec 9, 2015

@juliangruber how about this?

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@juliangruber juliangruber commented Dec 9, 2015

too edge-casy. koa should not need to worry about this.

Just to be sure, this would work for you, right?

httpStream.destroy = blackHole.bind(null, httpStream);
this.body = httpStream;

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@dead-horse dead-horse commented Dec 10, 2015

it is a common usage that use koa as a http proxy, and anybody who use this.body = yield request('http://foo.bar/'); //keep-alive will hit this "edge case", and it is really hard to figure out why. so I think we should fix it in framework level, because it is a bug in koa, and we can't let everyone to use httpStream.destroy = blackHole.bind(null, httpStream); hack.

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@jonathanong jonathanong commented Dec 21, 2015

maybe a better solution is to just wrap the http stream in another stream so you never set the http stream as the actual .body=.

const PassThrough = require('stream').PassThrough

app.use(function * (next) {
  this.body = httpStream.on('error', this.onerror).pipe(PassThrough())
})

would need docs on this though... super edge case

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@juliangruber juliangruber commented Dec 22, 2015

would need docs on this though... super edge case

what about documenting that a body stream can be .destroyed and showing how to guard against that

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@tejasmanohar tejasmanohar commented Jan 18, 2016

what about documenting that a body stream can be .destroyed and showing how to guard against that
Show all checks

+1 @juliangruber

@tejasmanohar tejasmanohar mentioned this pull request Feb 25, 2016
onFinish(this.res, function(){
// don't destroy http IncomingMessage, keep `keep-alive` conncetion alive.
if (val instanceof http.IncomingMessage) {
if (val.readable) val.pipe(new BlackHoleStream());
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@jonathanong jonathanong Feb 25, 2016

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why do you need black hole stream? just val.resume() to dump it

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@jonathanong jonathanong commented Feb 25, 2016

anyways prefer going the documentation route. will close this when i or someone else adds documentation

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@dead-horse dead-horse commented Feb 26, 2016

It's ok to add some warning in documentation.

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@catamphetamine catamphetamine commented Mar 6, 2017

Didn't understand a thing from the documentation on what's happening here.
It's just like "warning, never set a stream as ctx.body".

@jiajianrong
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@jiajianrong jiajianrong commented Aug 1, 2018

@catamphetamine, they were warning not to set a http-request-alike-stream which has keep-alive enabled. Because the framework will close the stream by default, which will break keep-alive feature.
Keep-alive means to reuse tcp socket connection for two or more http connections.

Generally, it's OK with ctx.body = fs-read-stream.
Just be careful with ctx.body = request('host:port/path').

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@rhinoceros rhinoceros commented Nov 12, 2018

@dead-horse
cnpmjs.org中目前用的koa的版本是"koa": "^1.2.0", 如果使用oss作为nfs, 在从oss上get的时候会有一堆的sockets hang up。

有什么好的办法能避免这类错误吗?

cnpm/cnpmjs.org#1401

谢谢

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9 participants