src: use env’s instead of isolate’s RequestInterrupt() + v8::Platform #32523

addaleax · 2020-03-27T20:48:31Z

src: make `Environment::interrupt_data_` atomic

Otherwise this potentially leads to race conditions when used in a
multi-threaded environment (i.e. when used for its very purpose).

src: fix cleanup hook removal for InspectorTimer

Fix this to account for the fact that Stop() may already have been
called from a cleanup hook when the inspector::Agent is deleted
along with the Environment, at which point cleanup hooks are no
longer available.

src: use env->RequestInterrupt() for inspector io thread start

This cleans up Agent::RequestIoThreadStart() significantly.

src: use env->RequestInterrupt() for inspector MainThreadInterface

This simplifies the code significantly, and removes the dependency of
the inspector code on the availability of a MultiIsolatePlatform
(by removing the dependency on a platform altogether).

It also fixes a memory leak that occurs when RequestInterrupt()
is used, but the interrupt handler is never called before the Isolate
is destroyed.

One downside is that this leads to a slight change in timing, because
inspector messages are not dispatched in a re-entrant way. This means
having to harden one test to account for that possibility by making
sure that the stack is always clear through a setImmediate().
This does not affect the assertion made by the test, which is that
messages will not be delivered synchronously while other code is
executing.

#32415

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
commit message follows commit guidelines

Otherwise this potentially leads to race conditions when used in a multi-threaded environment (i.e. when used for its very purpose).

Fix this to account for the fact that `Stop()` may already have been called from a cleanup hook when the `inspector::Agent` is deleted along with the `Environment`, at which point cleanup hooks are no longer available.

This cleans up `Agent::RequestIoThreadStart()` significantly.

This simplifies the code significantly, and removes the dependency of the inspector code on the availability of a `MultiIsolatePlatform` (by removing the dependency on a platform altogether). It also fixes a memory leak that occurs when `RequestInterrupt()` is used, but the interrupt handler is never called before the Isolate is destroyed. One downside is that this leads to a slight change in timing, because inspector messages are not dispatched in a re-entrant way. This means having to harden one test to account for that possibility by making sure that the stack is always clear through a `setImmediate()`. This does not affect the assertion made by the test, which is that messages will not be delivered synchronously while other code is executing. nodejs#32415

addaleax · 2020-03-27T20:49:21Z

src/inspector_js_api.cc

@@ -84,7 +84,7 @@ class JSBindingsConnection : public AsyncWrap {

   private:
    Environment* env_;
-    JSBindingsConnection* connection_;
+    BaseObjectPtr<JSBindingsConnection> connection_;


Btw, I’m not sure whether this is necessary anymore, but it was at one point while working on this, and it doesn’t hurt for the code to be a bit more robust here.

nodejs-github-bot · 2020-03-27T21:14:50Z

CI: https://ci.nodejs.org/job/node-test-pull-request/30135/

mmarchini

LGTM, but someone more familiar with inspector code should review it as well.

mmarchini · 2020-03-27T21:44:00Z

src/env.cc

+  Environment** interrupt_data = new Environment*(this);
+  Environment** dummy = nullptr;
+  if (!interrupt_data_.compare_exchange_strong(dummy, interrupt_data)) {
+    delete interrupt_data;
+    return;  // Already scheduled.
+  }


Maybe it's worth adding a comment here explaining what this code does.

@mmarchini Done, PTAL :)

mmarchini · 2020-03-27T21:50:24Z

src/env.cc

+  if (!interrupt_data_.compare_exchange_strong(dummy, interrupt_data)) {
+    delete interrupt_data;
+    return;  // Already scheduled.
+  }

  isolate()->RequestInterrupt([](Isolate* isolate, void* data) {


I don't remember if this callback runs asynchronously. Any chance we could get a situation where we request the interrupt here but don't run it before the Isolate is deleted? If that's possible, we would have a leak on interrupt_data.

Right – that is a possibility, but I don’t quite know what to do about it (without changing V8 APIs). The leak was already there before, too, and it’s limited to the size of a pointer…

Actually, I have an idea. Let me see. :)

Sure. If ASAN starts to complain, we can force it to ignore this pointer (for now ASAN is happy, so we can leave it as is).

@mmarchini 7e75cc1 should address this by flushing interrupts when freeing the Environment instance … feels a bit like a hack to me but I think it’s the best we can do :)

This avoids an edge-case memory leak. Refs: nodejs#32523 (comment)

nodejs-github-bot · 2020-03-28T00:16:03Z

CI: https://ci.nodejs.org/job/node-test-pull-request/30145/ (:heavy_check_mark:)

addaleax · 2020-04-08T14:42:22Z

ping @mmarchini

Otherwise this potentially leads to race conditions when used in a multi-threaded environment (i.e. when used for its very purpose). PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

Fix this to account for the fact that `Stop()` may already have been called from a cleanup hook when the `inspector::Agent` is deleted along with the `Environment`, at which point cleanup hooks are no longer available. PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This cleans up `Agent::RequestIoThreadStart()` significantly. PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This simplifies the code significantly, and removes the dependency of the inspector code on the availability of a `MultiIsolatePlatform` (by removing the dependency on a platform altogether). It also fixes a memory leak that occurs when `RequestInterrupt()` is used, but the interrupt handler is never called before the Isolate is destroyed. One downside is that this leads to a slight change in timing, because inspector messages are not dispatched in a re-entrant way. This means having to harden one test to account for that possibility by making sure that the stack is always clear through a `setImmediate()`. This does not affect the assertion made by the test, which is that messages will not be delivered synchronously while other code is executing. #32415 PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This avoids an edge-case memory leak. Refs: #32523 (comment) PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

addaleax · 2020-04-10T16:08:22Z

Landed in d0a3bf1...a173473

Otherwise this potentially leads to race conditions when used in a multi-threaded environment (i.e. when used for its very purpose). PR-URL: nodejs#32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

Fix this to account for the fact that `Stop()` may already have been called from a cleanup hook when the `inspector::Agent` is deleted along with the `Environment`, at which point cleanup hooks are no longer available. PR-URL: nodejs#32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This cleans up `Agent::RequestIoThreadStart()` significantly. PR-URL: nodejs#32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This simplifies the code significantly, and removes the dependency of the inspector code on the availability of a `MultiIsolatePlatform` (by removing the dependency on a platform altogether). It also fixes a memory leak that occurs when `RequestInterrupt()` is used, but the interrupt handler is never called before the Isolate is destroyed. One downside is that this leads to a slight change in timing, because inspector messages are not dispatched in a re-entrant way. This means having to harden one test to account for that possibility by making sure that the stack is always clear through a `setImmediate()`. This does not affect the assertion made by the test, which is that messages will not be delivered synchronously while other code is executing. nodejs#32415 PR-URL: nodejs#32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This avoids an edge-case memory leak. Refs: nodejs#32523 (comment) PR-URL: nodejs#32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This ensures that microtasks scheduled by native immediates are run after the tasks are done. In particular, this affects the inspector integration since 6f9f546. Fixes: nodejs#33002 Refs: nodejs#32523 PR-URL: nodejs#34366 Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de> Reviewed-By: James M Snell <jasnell@gmail.com>

Otherwise this potentially leads to race conditions when used in a multi-threaded environment (i.e. when used for its very purpose). Backport-PR-URL: #35241 PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

Fix this to account for the fact that `Stop()` may already have been called from a cleanup hook when the `inspector::Agent` is deleted along with the `Environment`, at which point cleanup hooks are no longer available. Backport-PR-URL: #35241 PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This cleans up `Agent::RequestIoThreadStart()` significantly. Backport-PR-URL: #35241 PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This simplifies the code significantly, and removes the dependency of the inspector code on the availability of a `MultiIsolatePlatform` (by removing the dependency on a platform altogether). It also fixes a memory leak that occurs when `RequestInterrupt()` is used, but the interrupt handler is never called before the Isolate is destroyed. One downside is that this leads to a slight change in timing, because inspector messages are not dispatched in a re-entrant way. This means having to harden one test to account for that possibility by making sure that the stack is always clear through a `setImmediate()`. This does not affect the assertion made by the test, which is that messages will not be delivered synchronously while other code is executing. #32415 Backport-PR-URL: #35241 PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This avoids an edge-case memory leak. Refs: #32523 (comment) Backport-PR-URL: #35241 PR-URL: #32523 Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: James M Snell <jasnell@gmail.com>

This ensures that microtasks scheduled by native immediates are run after the tasks are done. In particular, this affects the inspector integration since 6f9f546. Fixes: #33002 Refs: #32523 Backport-PR-URL: #35241 PR-URL: #34366 Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de> Reviewed-By: James M Snell <jasnell@gmail.com>

addaleax added 4 commits March 27, 2020 21:03

src: make Environment::interrupt_data_ atomic

171409a

Otherwise this potentially leads to race conditions when used in a multi-threaded environment (i.e. when used for its very purpose).

src: fix cleanup hook removal for InspectorTimer

4de323c

Fix this to account for the fact that `Stop()` may already have been called from a cleanup hook when the `inspector::Agent` is deleted along with the `Environment`, at which point cleanup hooks are no longer available.

src: use env->RequestInterrupt() for inspector io thread start

23b2da6

This cleans up `Agent::RequestIoThreadStart()` significantly.

addaleax requested review from eugeneo and mmarchini March 27, 2020 20:48

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 Mar 27, 2020

addaleax commented Mar 27, 2020

View reviewed changes

addaleax added the inspector Issues and PRs related to the V8 inspector protocol label Mar 27, 2020

mmarchini approved these changes Mar 27, 2020

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addaleax added 3 commits March 27, 2020 23:02

fixup! src: fix cleanup hook removal for InspectorTimer

d9689db

fixup! src: make Environment::interrupt_data_ atomic

aeb354d

src: flush V8 interrupts from Environment dtor

7e75cc1

This avoids an edge-case memory leak. Refs: nodejs#32523 (comment)

addaleax added the review wanted PRs that need reviews. label Apr 2, 2020

addaleax requested review from jasnell and mmarchini April 2, 2020 15:22

jasnell approved these changes Apr 10, 2020

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addaleax closed this Apr 10, 2020

addaleax deleted the inspector-requestinterrupt branch April 10, 2020 16:08

targos added the backport-requested-v13.x label Apr 11, 2020

addaleax added backport-open-v12.x and removed dont-land-on-v12.x labels Sep 17, 2020

addaleax mentioned this pull request Sep 17, 2020

[v12.x backport] src: improve embedder API #35241

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addaleax added backported-to-v12.x and removed backport-open-v12.x labels Sep 23, 2020

codebytere mentioned this pull request Sep 28, 2020

v12.19.0 proposal #35401

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src: use env’s instead of isolate’s RequestInterrupt() + v8::Platform #32523

src: use env’s instead of isolate’s RequestInterrupt() + v8::Platform #32523

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src: use env’s instead of isolate’s RequestInterrupt() + v8::Platform #32523

src: use env’s instead of isolate’s RequestInterrupt() + v8::Platform #32523

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addaleax commented Mar 27, 2020

src: make Environment::interrupt_data_ atomic

src: fix cleanup hook removal for InspectorTimer

src: use env->RequestInterrupt() for inspector io thread start

src: use env->RequestInterrupt() for inspector MainThreadInterface

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src: make `Environment::interrupt_data_` atomic

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