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Child process/streams memory leak #4049

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jhenninger opened this issue Nov 27, 2015 · 2 comments
Closed

Child process/streams memory leak #4049

jhenninger opened this issue Nov 27, 2015 · 2 comments
Labels
child_process Issues and PRs related to the child_process subsystem. memory Issues and PRs related to the memory management or memory footprint.

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@jhenninger
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The following code is leaking memory. I tested this using node-inspector and taking heap snapshots in chrome.

var cp = require('child_process');

setInterval(function () {
  var p = cp.spawn('yes');

  p.stdout.read();
  p.kill();
}, 50);

The leak stops if the p.stdout.read(); line is removed.

Another test, requires weak:

var cp = require('child_process');
var weak = require('weak');

var c = 0;

function cb() {
  console.log(--c);
}

setInterval(function () {
  var p = cp.spawn('yes');

  ++c;

  p.stdout.read();
  p.kill();

  weak(p, cb);

  gc();

}, 50);

Running this with --expose-gc will display the the number of process instances that haven't been garbaged collected. The number will always be counting up and never decrease.

If the p.stdout.read() line is removed, there will always be only one process object waiting to be collected.

@mscdex mscdex added the child_process Issues and PRs related to the child_process subsystem. label Nov 27, 2015
@ChALkeR ChALkeR added the memory Issues and PRs related to the memory management or memory footprint. label Nov 28, 2015
@davidvgalbraith
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+1. The leak also seems to go away if you replace p.stdout.read() with p.stdout.read(0) or p.stdin.read() or p.stderr.read().

davidvgalbraith pushed a commit to davidvgalbraith/node that referenced this issue Nov 30, 2015
When a client calls read() with a nonzero argument
on a Socket, that Socket sets this._consuming to true.
It never sets this._consuming back to false.
child_process.flushStdio currently doesn't flush
any streams where _consuming is truthy. But that means
that it never flushes any stream that has ever been read from.
This prevents a child process from ever closing if one of
its streams has been read from, causing issue nodejs#4049.

child_process.flushStdio should flush streams even if their
_consuming is set to true. Then it will close even after a read.
@davidvgalbraith
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I found this one interesting and untoward, so I took a crack at it: #4071.

@cjihrig cjihrig closed this as completed in 34b535f Dec 1, 2015
rvagg pushed a commit that referenced this issue Dec 5, 2015
When a client calls read() with a nonzero argument
on a Socket, that Socket sets this._consuming to true.
It never sets this._consuming back to false.
ChildProcess.flushStdio() currently doesn't flush
any streams where _consuming is truthy. But, that means
that it never flushes any stream that has ever been read from.
This prevents a child process from ever closing if one of
its streams has been read from, causing issue #4049. This
commit allows consuming streams to be flushed, and the
child process to emit a close event.

Fixes: #4049
PR-URL: #4071
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
MylesBorins pushed a commit that referenced this issue Jan 13, 2016
When a client calls read() with a nonzero argument
on a Socket, that Socket sets this._consuming to true.
It never sets this._consuming back to false.
ChildProcess.flushStdio() currently doesn't flush
any streams where _consuming is truthy. But, that means
that it never flushes any stream that has ever been read from.
This prevents a child process from ever closing if one of
its streams has been read from, causing issue #4049. This
commit allows consuming streams to be flushed, and the
child process to emit a close event.

Fixes: #4049
PR-URL: #4071
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
MylesBorins pushed a commit that referenced this issue Jan 19, 2016
When a client calls read() with a nonzero argument
on a Socket, that Socket sets this._consuming to true.
It never sets this._consuming back to false.
ChildProcess.flushStdio() currently doesn't flush
any streams where _consuming is truthy. But, that means
that it never flushes any stream that has ever been read from.
This prevents a child process from ever closing if one of
its streams has been read from, causing issue #4049. This
commit allows consuming streams to be flushed, and the
child process to emit a close event.

Fixes: #4049
PR-URL: #4071
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
scovetta pushed a commit to scovetta/node that referenced this issue Apr 2, 2016
When a client calls read() with a nonzero argument
on a Socket, that Socket sets this._consuming to true.
It never sets this._consuming back to false.
ChildProcess.flushStdio() currently doesn't flush
any streams where _consuming is truthy. But, that means
that it never flushes any stream that has ever been read from.
This prevents a child process from ever closing if one of
its streams has been read from, causing issue nodejs#4049. This
commit allows consuming streams to be flushed, and the
child process to emit a close event.

Fixes: nodejs#4049
PR-URL: nodejs#4071
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
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Labels
child_process Issues and PRs related to the child_process subsystem. memory Issues and PRs related to the memory management or memory footprint.
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