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http2,tls: store WriteWrap using BaseObjectPtr #35488

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@addaleax addaleax commented Oct 3, 2020

Create weak WriteWrap and ShutdownWrap objects, and when
referencing them in C++ is necessary, use BaseObjectPtr<>
instead of plain pointers to keep these objects from being
garbage-collected.

This solves issues that arise when the underlying StreamBase
instance is weak, but the WriteWrap or ShutdownWrap instances
are not; in that case, they would otherwise potentially stick
around in memory after the stream that they originally belong
to is long gone.

It probably makes sense to use BaseObjectptr<> more extensively
in StreamBase in the long run as well.

Checklist
  • make -j4 test (UNIX), or vcbuild test (Windows) passes
  • commit message follows commit guidelines

Create weak `WriteWrap` and `ShutdownWrap` objects, and when
referencing them in C++ is necessary, use `BaseObjectPtr<>`
instead of plain pointers to keep these objects from being
garbage-collected.

This solves issues that arise when the underlying `StreamBase`
instance is weak, but the `WriteWrap` or `ShutdownWrap` instances
are not; in that case, they would otherwise potentially stick
around in memory after the stream that they originally belong
to is long gone.

It probably makes sense to use `BaseObjectptr<>` more extensively
in `StreamBase` in the long run as well.
@addaleax addaleax added tls Issues and PRs related to the tls subsystem. http2 Issues or PRs related to the http2 subsystem. lts-watch-v12.x request-ci Add this label to start a Jenkins CI on a PR. labels Oct 3, 2020
@addaleax addaleax requested review from a team as code owners October 3, 2020 22:47
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Review requested:

  • @nodejs/http2
  • @nodejs/net

@nodejs-github-bot nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. lib / src Issues and PRs related to general changes in the lib or src directory. labels Oct 3, 2020
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addaleax added a commit to addaleax/node that referenced this pull request Oct 3, 2020
When a process exits cleanly, i.e. because the event loop ends up
without things to wait for, the Node.js objects that are left on
the heap should be:

 1. weak, i.e. ready for garbage collection once no longer
    referenced, or
 2. detached, i.e. scheduled for destruction once no longer
    referenced, or
 3. an unrefed libuv handle, i.e. does not keep the event loop
    alive, or
 4. an inactive libuv handle (essentially the same here)

There are a few exceptions to this rule, but generally,
if there are C++-backed Node.js objects on the heap
that do not fall into the above categories, we may be looking
at a potential memory leak. Most likely, the cause is a missing
`MakeWeak()` call on the corresponding object.

In order to avoid this kind of problem, we check the list
of BaseObjects for these criteria. In this commit, we only do so
when explicitly instructed to or when in debug mode
(where --verify-base-objects is always-on).

In particular, this avoids the kinds of memory leak issues
that were fixed in the PRs referenced below.

Refs: nodejs#35488
Refs: nodejs#35487
Refs: nodejs#35481
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lgtm

@addaleax addaleax added request-ci Add this label to start a Jenkins CI on a PR. and removed request-ci Add this label to start a Jenkins CI on a PR. labels Oct 4, 2020
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@addaleax addaleax added author ready PRs that have at least one approval, no pending requests for changes, and a CI started. request-ci Add this label to start a Jenkins CI on a PR. labels Oct 4, 2020
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addaleax commented Oct 6, 2020

Landed in 78e5875

@addaleax addaleax closed this Oct 6, 2020
addaleax added a commit that referenced this pull request Oct 6, 2020
Create weak `WriteWrap` and `ShutdownWrap` objects, and when
referencing them in C++ is necessary, use `BaseObjectPtr<>`
instead of plain pointers to keep these objects from being
garbage-collected.

This solves issues that arise when the underlying `StreamBase`
instance is weak, but the `WriteWrap` or `ShutdownWrap` instances
are not; in that case, they would otherwise potentially stick
around in memory after the stream that they originally belong
to is long gone.

It probably makes sense to use `BaseObjectptr<>` more extensively
in `StreamBase` in the long run as well.

PR-URL: #35488
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
@addaleax addaleax deleted the stream-base-writewrap branch October 6, 2020 11:26
@danielleadams danielleadams mentioned this pull request Oct 6, 2020
danielleadams pushed a commit that referenced this pull request Oct 6, 2020
Create weak `WriteWrap` and `ShutdownWrap` objects, and when
referencing them in C++ is necessary, use `BaseObjectPtr<>`
instead of plain pointers to keep these objects from being
garbage-collected.

This solves issues that arise when the underlying `StreamBase`
instance is weak, but the `WriteWrap` or `ShutdownWrap` instances
are not; in that case, they would otherwise potentially stick
around in memory after the stream that they originally belong
to is long gone.

It probably makes sense to use `BaseObjectptr<>` more extensively
in `StreamBase` in the long run as well.

PR-URL: #35488
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
addaleax added a commit that referenced this pull request Oct 7, 2020
When a process exits cleanly, i.e. because the event loop ends up
without things to wait for, the Node.js objects that are left on
the heap should be:

 1. weak, i.e. ready for garbage collection once no longer
    referenced, or
 2. detached, i.e. scheduled for destruction once no longer
    referenced, or
 3. an unrefed libuv handle, i.e. does not keep the event loop
    alive, or
 4. an inactive libuv handle (essentially the same here)

There are a few exceptions to this rule, but generally,
if there are C++-backed Node.js objects on the heap
that do not fall into the above categories, we may be looking
at a potential memory leak. Most likely, the cause is a missing
`MakeWeak()` call on the corresponding object.

In order to avoid this kind of problem, we check the list
of BaseObjects for these criteria. In this commit, we only do so
when explicitly instructed to or when in debug mode
(where --verify-base-objects is always-on).

In particular, this avoids the kinds of memory leak issues
that were fixed in the PRs referenced below.

Refs: #35488
Refs: #35487
Refs: #35481

PR-URL: #35490
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
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This doesn't land cleanly on 12.x. As 12.x is about to move to maintenance I'm unsure if it makes sense to backport. We could still potentially get this in the 12.20.0 release if it is backported in a timely fashion, but it isn't clear that this is high priority.

joesepi pushed a commit to joesepi/node that referenced this pull request Jan 8, 2021
Create weak `WriteWrap` and `ShutdownWrap` objects, and when
referencing them in C++ is necessary, use `BaseObjectPtr<>`
instead of plain pointers to keep these objects from being
garbage-collected.

This solves issues that arise when the underlying `StreamBase`
instance is weak, but the `WriteWrap` or `ShutdownWrap` instances
are not; in that case, they would otherwise potentially stick
around in memory after the stream that they originally belong
to is long gone.

It probably makes sense to use `BaseObjectptr<>` more extensively
in `StreamBase` in the long run as well.

PR-URL: nodejs#35488
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
joesepi pushed a commit to joesepi/node that referenced this pull request Jan 8, 2021
When a process exits cleanly, i.e. because the event loop ends up
without things to wait for, the Node.js objects that are left on
the heap should be:

 1. weak, i.e. ready for garbage collection once no longer
    referenced, or
 2. detached, i.e. scheduled for destruction once no longer
    referenced, or
 3. an unrefed libuv handle, i.e. does not keep the event loop
    alive, or
 4. an inactive libuv handle (essentially the same here)

There are a few exceptions to this rule, but generally,
if there are C++-backed Node.js objects on the heap
that do not fall into the above categories, we may be looking
at a potential memory leak. Most likely, the cause is a missing
`MakeWeak()` call on the corresponding object.

In order to avoid this kind of problem, we check the list
of BaseObjects for these criteria. In this commit, we only do so
when explicitly instructed to or when in debug mode
(where --verify-base-objects is always-on).

In particular, this avoids the kinds of memory leak issues
that were fixed in the PRs referenced below.

Refs: nodejs#35488
Refs: nodejs#35487
Refs: nodejs#35481

PR-URL: nodejs#35490
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
addaleax added a commit to addaleax/node that referenced this pull request May 23, 2021
When a process exits cleanly, i.e. because the event loop ends up
without things to wait for, the Node.js objects that are left on
the heap should be:

 1. weak, i.e. ready for garbage collection once no longer
    referenced, or
 2. detached, i.e. scheduled for destruction once no longer
    referenced, or
 3. an unrefed libuv handle, i.e. does not keep the event loop
    alive, or
 4. an inactive libuv handle (essentially the same here)

There are a few exceptions to this rule, but generally,
if there are C++-backed Node.js objects on the heap
that do not fall into the above categories, we may be looking
at a potential memory leak. Most likely, the cause is a missing
`MakeWeak()` call on the corresponding object.

In order to avoid this kind of problem, we check the list
of BaseObjects for these criteria. In this commit, we only do so
when explicitly instructed to or when in debug mode
(where --verify-base-objects is always-on).

In particular, this avoids the kinds of memory leak issues
that were fixed in the PRs referenced below.

Refs: nodejs#35488
Refs: nodejs#35487
Refs: nodejs#35481

PR-URL: nodejs#35490
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
targos pushed a commit that referenced this pull request May 25, 2021
When a process exits cleanly, i.e. because the event loop ends up
without things to wait for, the Node.js objects that are left on
the heap should be:

 1. weak, i.e. ready for garbage collection once no longer
    referenced, or
 2. detached, i.e. scheduled for destruction once no longer
    referenced, or
 3. an unrefed libuv handle, i.e. does not keep the event loop
    alive, or
 4. an inactive libuv handle (essentially the same here)

There are a few exceptions to this rule, but generally,
if there are C++-backed Node.js objects on the heap
that do not fall into the above categories, we may be looking
at a potential memory leak. Most likely, the cause is a missing
`MakeWeak()` call on the corresponding object.

In order to avoid this kind of problem, we check the list
of BaseObjects for these criteria. In this commit, we only do so
when explicitly instructed to or when in debug mode
(where --verify-base-objects is always-on).

In particular, this avoids the kinds of memory leak issues
that were fixed in the PRs referenced below.

Refs: #35488
Refs: #35487
Refs: #35481

PR-URL: #35490
Backport-PR-URL: #38786
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
targos pushed a commit that referenced this pull request Jun 11, 2021
When a process exits cleanly, i.e. because the event loop ends up
without things to wait for, the Node.js objects that are left on
the heap should be:

 1. weak, i.e. ready for garbage collection once no longer
    referenced, or
 2. detached, i.e. scheduled for destruction once no longer
    referenced, or
 3. an unrefed libuv handle, i.e. does not keep the event loop
    alive, or
 4. an inactive libuv handle (essentially the same here)

There are a few exceptions to this rule, but generally,
if there are C++-backed Node.js objects on the heap
that do not fall into the above categories, we may be looking
at a potential memory leak. Most likely, the cause is a missing
`MakeWeak()` call on the corresponding object.

In order to avoid this kind of problem, we check the list
of BaseObjects for these criteria. In this commit, we only do so
when explicitly instructed to or when in debug mode
(where --verify-base-objects is always-on).

In particular, this avoids the kinds of memory leak issues
that were fixed in the PRs referenced below.

Refs: #35488
Refs: #35487
Refs: #35481

PR-URL: #35490
Backport-PR-URL: #38786
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
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