inspector: added NodeRuntime domain #27600

alexkozy · 2019-05-07T18:02:49Z

Historically Node process sends Runtime.executionContextDestroyed
with main context as argument when it is finished.
This approach has some disadvantages. V8 prevents running some
protocol command on destroyed contexts, e.g. Runtime.evaluate
will return an error or Debugger.enable won't return a list of
scripts.
Both command might be useful for different tools, e.g. tool runs
Profiler.startPreciseCoverage and at the end of node process it
would like to get list of all scripts to match data to source code.
Or some tooling frontend would like to provide capabilities to run
commands in console when node process is finished to allow user to
inspect state of the program at exit.
This PR adds new domain: NodeRuntime. This domain sends
NodeRuntime.waitingForDisconnect when this event is enabled.

Checklist

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

nodejs-github-bot · 2019-05-07T18:02:51Z

Lite-CI: https://ci.nodejs.org/job/node-test-pull-request-lite-pipeline/3453

src/inspector_agent.cc

eugeneo

Thanks for working on this!

src/inspector/node_protocol.pdl

src/inspector_agent.cc

eugeneo · 2019-05-07T18:22:51Z

src/inspector_agent.cc

@@ -779,7 +797,8 @@ void Agent::WaitForDisconnect() {
  }
  // TODO(addaleax): Maybe this should use an at-exit hook for the Environment
  // or something similar?
-  client_->contextDestroyed(parent_env_->context());
+  if (!client_->reportWaitingForDebuggerToDisconnect())


Maybe put this to NodeInspectorClient::contextDestroyed?

I'd like to have it here, otherwise in future someone might use contextDestroyed in other places and get misleading notification.

Feel free to rename "contextDestroyed" to something else - like "mainContextDone"?

src/inspector/runtime_agent.cc

eugeneo · 2019-05-08T17:15:14Z

src/inspector/node_protocol.pdl

+experimental domain NodeRuntime
+  # When domain is enabled `NodeRuntime.waitingForDisconnect` will be issued at the end of node process.
+  # Please see `NodeRuntime.waitingForDisconnect` for more details.
+  command enable


"enable" seems to generic a verb for this very specific task. Maybe "retainMainContextForDebugger"?

Renamed to notifyWhenWaitingForDisconnect.

Did you forget to push the change?

it looks like something went wrong yesterday, I just pushed updated version.

src/inspector/node_protocol.pdl

eugeneo · 2019-05-08T17:18:00Z

src/inspector_agent.cc

@@ -779,7 +797,8 @@ void Agent::WaitForDisconnect() {
  }
  // TODO(addaleax): Maybe this should use an at-exit hook for the Environment
  // or something similar?
-  client_->contextDestroyed(parent_env_->context());
+  if (!client_->reportWaitingForDebuggerToDisconnect())


Feel free to rename "contextDestroyed" to something else - like "mainContextDone"?

eugeneo

Thanks for working on this!

alexkozy

@eugeneo please take another look.

eugeneo · 2019-05-09T18:10:38Z

src/inspector/node_protocol.pdl

+  # Event is issued when Node process is finished and waiting for debugger to disconnect.
+  # When enabled client should listen for this event instead of `Runtime.executionContextDestroyed`
+  # to check wether node process is finished.
+  event waitingForDisconnect


I believe it needs to be communecated clearly on the purpose of this notification vs the Runtime.executionContextDestroyed - specifically, that the main context is retained and can still be used.

I updated comment.

eugeneo · 2019-05-09T18:23:11Z

src/inspector_agent.cc

@@ -610,6 +620,14 @@ class NodeInspectorClient : public V8InspectorClient {
    return false;
  }

+  bool notifyWaitingForDisconnect() {
+    for (const auto& id_channel : channels_) {
+      if (id_channel.second->notifyWaitingForDisconnect())


It looks like this notification will only get sent to the sessions that requested it. Others will get nothing, not even an Runtime.executionContextDestroyed.

I suggest sending other sessions executionContextDestroyed either as al else statement for this if or at a later point, once all sessions that requested a disconnect notification disconnect.

It is not possible to send executionContextDestroyed without dirty hacks. We need to intercept every Runtime.enable and Runtime.disable calls to maintain runtime enabled state on node side. At the same time we can not just calls executionContextDestroyed on inspector since then inspector will mark context as destroyed and any later calls that uses Runtime will return an error.

Based on how much hacks we need to add, how many clients there are in a wild right now, what is probability of using new client and old client at the same time I believe that we can just send nothing here. Protocol definition stated exactly this.

I tried to adopt solution that you proposed and it seems like it works!

eugeneo

Thanks!

nodejs-github-bot · 2019-05-13T08:35:10Z

CI: https://ci.nodejs.org/job/node-test-pull-request/23078/

eugeneo · 2019-05-13T20:03:32Z

Looks like this PR needs to be rebased by hand.

Trott · 2019-05-13T22:29:12Z

Looks like this PR needs to be rebased by hand.

If you are having CI difficulties, the actual problem is almost certainly the merge-commit. Our Jenkins setup often (always?) does not handle merge-commits well. Squash the merge-commit into the other commit or force-push the merge-commit out, and then CI should be fine.

nodejs-github-bot · 2019-05-14T01:15:07Z

CI: https://ci.nodejs.org/job/node-test-pull-request/23102/

Historically Node process sends Runtime.executionContextDestroyed with main context as argument when it is finished. This approach has some disadvantages. V8 prevents running some protocol command on destroyed contexts, e.g. Runtime.evaluate will return an error or Debugger.enable won't return a list of scripts. Both command might be useful for different tools, e.g. tool runs Profiler.startPreciseCoverage and at the end of node process it would like to get list of all scripts to match data to source code. Or some tooling frontend would like to provide capabilities to run commands in console when node process is finished to allow user to inspect state of the program at exit. This PR adds new domain: NodeRuntime. After NodeRuntime.notifyWhenWaitingForDisconnect is enabled by at least one client, node will send NodeRuntime.waitingForDebuggerToDisconnect event instead of Runtime.executionContextDestroyed. Based on this signal any protocol client can capture all required information and then disconnect its session.

nodejs-github-bot · 2019-05-14T20:18:15Z

CI: https://ci.nodejs.org/job/node-test-pull-request/23112/

nodejs-github-bot · 2019-05-14T20:55:41Z

CI: https://ci.nodejs.org/job/node-test-pull-request/23117/

Trott

Test LGTM. Rest of it is RSLGTM/defer-to-@eugeneo-and-others.

alexkozy · 2019-05-14T23:15:21Z

Landed in 10d7e01

git node land $PRID tool is amazing!

Historically Node process sends Runtime.executionContextDestroyed with main context as argument when it is finished. This approach has some disadvantages. V8 prevents running some protocol command on destroyed contexts, e.g. Runtime.evaluate will return an error or Debugger.enable won't return a list of scripts. Both command might be useful for different tools, e.g. tool runs Profiler.startPreciseCoverage and at the end of node process it would like to get list of all scripts to match data to source code. Or some tooling frontend would like to provide capabilities to run commands in console when node process is finished to allow user to inspect state of the program at exit. This PR adds new domain: NodeRuntime. After NodeRuntime.notifyWhenWaitingForDisconnect is enabled by at least one client, node will send NodeRuntime.waitingForDebuggerToDisconnect event instead of Runtime.executionContextDestroyed. Based on this signal any protocol client can capture all required information and then disconnect its session. PR-URL: #27600 Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com> Reviewed-By: Rich Trott <rtrott@gmail.com>

alexkozy requested a review from eugeneo May 7, 2019 18:02

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 May 7, 2019

alexkozy added the inspector Issues and PRs related to the V8 inspector protocol label May 7, 2019

alexkozy force-pushed the node-runtime-agent-2 branch from 74a3c97 to 07f50b5 Compare May 7, 2019 18:10

addaleax reviewed May 7, 2019

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alexkozy force-pushed the node-runtime-agent-2 branch 2 times, most recently from 2e3c872 to 051a90c Compare May 7, 2019 20:01

alexkozy requested a review from eugeneo May 8, 2019 00:13

eugeneo reviewed May 8, 2019

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alexkozy force-pushed the node-runtime-agent-2 branch from 051a90c to 020da49 Compare May 8, 2019 18:34

alexkozy commented May 8, 2019

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alexkozy force-pushed the node-runtime-agent-2 branch from 020da49 to 1a3f130 Compare May 9, 2019 17:02

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This was referenced May 10, 2019

inspector: implement --heap-prof #27596

Closed

RFC: add a flag --heap-prof (similar to --cpu-prof but for the heap) #27421

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eugeneo approved these changes May 10, 2019

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BridgeAR added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label May 13, 2019

eugeneo mentioned this pull request May 13, 2019

inspector: add way to force worker to wait inspector session detach #27677

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alexkozy force-pushed the node-runtime-agent-2 branch 2 times, most recently from c7c45b4 to 0c5cb42 Compare May 13, 2019 23:43

alexkozy force-pushed the node-runtime-agent-2 branch from 0c5cb42 to 6ecbb2c Compare May 13, 2019 23:44

alexkozy force-pushed the node-runtime-agent-2 branch from 6ecbb2c to d53eb62 Compare May 14, 2019 19:58

alexkozy self-assigned this May 14, 2019

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BridgeAR mentioned this pull request May 21, 2019

v12.3.0 proposal #27799

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nornagon mentioned this pull request Oct 7, 2020

Main process disappears from dedicated Node.js devtools window on exit when awaiting debugger detach electron/electron#25807

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inspector: added NodeRuntime domain #27600

inspector: added NodeRuntime domain #27600

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inspector: added NodeRuntime domain #27600

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