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process: Change default --unhandled-rejections=throw #33021

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dfabulich
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@dfabulich dfabulich commented Apr 23, 2020

This is a semver-major change that resolves DEP0018.

All users that have set an unhandledRejection hook or set a non-default
value for the --unhandled-rejections flag will see no change in behavior
after this change.

Fixes: #20392
Refs: https://nodejs.org/dist/latest/docs/api/deprecations.html#deprecations_dep0018_unhandled_promise_rejections

Checklist
  • make -j4 test (UNIX), or vcbuild test (Windows) passes
  • tests and/or benchmarks are included
  • documentation is changed or added
  • commit message follows commit guidelines

@nodejs-github-bot nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. process Issues and PRs related to the process subsystem. labels Apr 23, 2020
@dfabulich
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While working on PR #32986, I found that I had to do an unnecessarily large amount of work updating the tests. This first led me to implement PR #33017 as a stepping stone, but @BridgeAR expressed disapproval, so I figured I'd close PR #32986 and open this PR.

This PR, I claim, is the simplest thing that could possibly work. I think it will be more appealing than my earlier PR #32986 because it provides a way for users who don't want strict mode to escape it: users can set an unhandledRejection hook and get full control over the default behavior.

At the same time, users who set a CLI flag will maintain full control over unhandled rejections, even if userland code attempts to override it.

  • If you're one of the folks who think rejected Promises aren't really exceptional, that's fine! You can use this one-liner to get the behavior you want: process.on('unhandledRejection', () => {}). (You probably already have a line like that in your code today, to suppress the unsightly UnhandledPromiseRejectionWarning and the deprecation notice.) You can also use the CLI flag --unhandled-rejections=none, if that suits you better.
  • If you care about ensuring your environment is consistent and that random hooks can't change the behavior of your unhandled rejections, you can keep using the CLI flags you've been using since Node 10. None of the explicit flag values (none, warn, strict) have changed their behavior, and they all continue to override whatever behavior is set in the unhandledRejections hook. (Only the old default behavior honored that hook; the new default behavior continues to honor the hook.)
  • If you're just a humble cavedweller like me, and you just want to terminate the process when you throw an uncaught Error in an async function, this PR is for you!

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I have the same blocking concerns here as I did in the other PR.

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@devsnek would you mind to add a link?

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lgtm

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cc @nodejs/tsc

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nodejs-github-bot commented Apr 23, 2020

@mcollina mcollina added the semver-major PRs that contain breaking changes and should be released in the next major version. label Apr 23, 2020
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ljharb commented Apr 23, 2020

This should never be on by default; the language spec does not intend Promise.reject(), or the equivalent, to inherently crash the process under any circumstances.

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The language spec does not intend throw new Error() to inherently crash the process under any circumstances, even in synchronous code. But in Node, it's useful to have throw new Error() crash the process. It is just as useful to have throw new Error() crash the process in an async function. This is why crowds keep forming around this feature.

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ljharb commented Apr 23, 2020

I don't agree - an uncaught throw is intended to catch the process. Promise rejections are not the same as synchronous thrown exceptions, and shouldn't be treated the same.

I'm not objecting to the (existing) ways people can opt in to making the process exit, on any criteria they want. By default, however, this would be a very destructive setting.

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dfabulich commented Apr 23, 2020

an uncaught throw is intended to [crash] the process

Can you provide a link? There's no statement about this in any version of the ECMAScript specification that I'm aware of. (But of course there wouldn't be. Browsers never "crash the process.")

Node allows users to attach an uncaughtException event handler and resolve it in a way that doesn't crash the process. This doesn't bring Node out of compliance with the language spec, because the spec doesn't say what the runtime is supposed to do with an uncaught exception at all.

this would be a very destructive setting

"Destructive" isn't the right word to use here. This PR will have no effect on anyone using the --unhandled-rejections flag today, or on anyone who uses the unhandledRejections hook. It will literally only impact people who are currently seeing DEP0018 in their warnings.

Everyone who has seen that warning since Node 10 was released and has taken some action to suppress it, any action at all, will not be impacted by this PR.

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dfabulich commented Apr 23, 2020

Load two scripts, throw a synchronous exception without catching on the first, the second won't run

That's not true. In this jsbin, the second script runs.

https://jsbin.com/juxinik/1/edit?html,output

(edit: pasted wrong link)

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Oh, interesting. I swear I had issues with that in the past, might be confusing with something else though.

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I would note that this definitely helps developers, and it is the default behavior in Deno. My opinion is that we should get this landed for v15.

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jasnell commented Apr 23, 2020

While I have many issues with Promises and absolutely think that crashing on unhandled rejections is good for developers, I'm less convinced that we should crash by default and I do think we should remove the existing deprecation warning. The default behavior should continue to be to warn on the unhandled rejection.

So, just to be clear, I'm -1 on this PR

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@jasnell How do you feel about #32986 (comment)?

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jasnell commented Apr 23, 2020

Specifically on setting exitCode = 1 on unhandled rejection? I think that's reasonable but without additional information it could make it difficult to reason about what caused the exitCode to be non-zero. It could become a bit of a nightmare to diagnose.

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I'm in favor of raising an exception by default (so +1 on this PR). As a fallback, I'm in favor of removing the deprecation and keep the warning, as long as the process returns an error code by default when it exits if there are pending unhandled rejections. I'm -1 on just removing the deprecation and exiting successfully.

@BridgeAR BridgeAR added the tsc-agenda Issues and PRs to discuss during the meetings of the TSC. label Apr 23, 2020
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@jasnell We do currently say in the deprecation warning that that’s what we’re going to do, and we could still keep it in the warning text (to be clear, I’m not suggesting to remove the warning, ever) 🤷‍♀️

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devsnek commented Apr 23, 2020

I'm also in favor of the default mode continuing to be warn.

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jasnell commented Apr 23, 2020

Thinking through this while discussing on the tsc call, I think the process that I would like to see here is:

  1. Setting strict mode would take highest priority and would throw and crash immediately.
  2. Otherwise, if the unhandledRejection handler is in place, pass the rejection to that with no warning emitted.
  3. Otherwise, if the throw mode (what this PR calls default) is set, throw the rejection as an uncaught exception.
  4. Otherwise, if the none mode is set, do nothing.
  5. Otherwise, emit the unhandledRejection warning and set exitCode = 1
  6. Remove the existing deprecation warning.

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ljharb commented Apr 23, 2020

@jasnell my position (and one which imo reflects the intention of the JS spec) is that the none mode should be the default.

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devsnek commented Apr 23, 2020

@ljharb I'm not so sure about that... HostPromiseRejectionTracker exists for a reason.

@richardlau richardlau added the notable-change PRs with changes that should be highlighted in changelogs. label Sep 22, 2020
@benjamingr
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And... 5 years later, I feel like my biggest regret regarding promises early on in Node was finally fixed 🎉 Chapeau!

If anyone is wondering there is still a ton of interesting work to do in this space and improvement ideas/suggestions.

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Also 5 years later, I still believe this is the correct choice for Node.js. Thank you.

BethGriggs added a commit that referenced this pull request Oct 19, 2020
Notable changes:

Deprecations and Removals:

- **build**: remove --build-v8-with-gn configure option (Yang Guo)
(#27576)
- **build**: drop support for VS2017 (Michaël Zasso)
(#33694)
- **doc**: move DEP0018 to End-of-Life (Rich Trott)
(#35316)
- **fs**: deprecation warning on recursive rmdir (Ian Sutherland)
(#35562)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **net**: remove long deprecated server.connections property (James M
Snell) (#33647)
- **repl**: remove deprecated repl.memory function (Ruben Bridgewater)
(#33286)
- **repl**: remove deprecated repl.turnOffEditorMode() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated repl.parseREPLKeyword() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated bufferedCommand property (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated .rli (Ruben Bridgewater)
(#33286)
- **src**: remove deprecated node debug command (James M Snell)
(#33648)
- **timers**: introduce timers/promises (James M Snell)
(#33950)
- **util**: change default value of `maxStringLength` to 10000
(unknown) (#32744)
- **wasi**: drop --experimental-wasm-bigint requirement (Colin Ihrig)
(#35415)

npm 7 (#35631):

Node.js 15 comes with a new major release of npm, npm 7. npm 7 comes
with many new features - including npm workspaces and a new
package-lock.json format. npm 7 also includes yarn.lock file support.
One of the big changes in npm 7 is that peer dependencies are now
installed by default.

Throw On Unhandled Rejections
(#33021):

As of Node.js 15, the default mode for `unhandledRejection` is changed
to `throw` (from `warn`). In `throw` mode, if an `unhandledRejection`
hook is not set, the `unhandledRejection` is raised as an uncaught
exception. Users that have an `unhandledRejection` hook should see no
change in behavior, and it’s still possible to switch modes using the
`--unhandled-rejections=mode` process flag.

QUIC (#32379):

Node.js 15 comes with experimental support QUIC, which can be enabled
by compiling Node.js with the `--experimental-quic` configuration flag.
The Node.js QUIC implementation is exposed by the core `net` module.

V8 8.6 (#35415):

The V8 JavaScript engine has been updated to V8 8.6 (V8 8.4 is the
latest available in Node.js 14). Along with performance tweaks and
improvements the V8 update also brings the following language features:
* `Promise.any()` (from V8 8.5)
* `AggregateError` (from V8 8.5)
* `String.prototype.replaceAll()` (from V8 8.5)
* Logical assignment operators `&&=`, `||=`, and `??=` (from V8 8.5)

Other Notable Changes:

- **assert**: add `assert/strict` alias module (ExE Boss)
(#34001)
- **dns**: add dns/promises alias (shisama)
(#32953)
- **fs**: reimplement read and write streams using stream.construct
(Robert Nagy) (#29656)
- **http2**: allow Host in HTTP/2 requests (Alba Mendez)
(#34664)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **lib**: unflag AbortController (James M Snell)
(#33527)
- **lib**: initial experimental AbortController implementation (James M
Snell) (#33527)
- **net**: autoDestroy Socket (Robert Nagy)
(#31806)
- **src**: disallow JS execution inside FreeEnvironment (Anna
Henningsen) (#33874)
- **stream**: construct (Robert Nagy)
(#29656)
- **worker**: make MessageEvent class more Web-compatible (Anna
Henningsen) (#35496)

Semver-Major Commits:

- **assert**: add `assert/strict` alias module (ExE Boss)
(#34001)
- **build**: reset embedder string to "-node.0" (Michaël Zasso)
(#35415)
- **build**: remove --build-v8-with-gn configure option (Yang Guo)
(#27576)
- **build**: drop support for VS2017 (Michaël Zasso)
(#33694)
- **crypto**: refactoring internals, add WebCrypto (James M Snell)
(#35093)
- **crypto**: move node\_crypto files to src/crypto (James M Snell)
(#35093)
- **deps**: V8: cherry-pick d76abfed3512 (Michaël Zasso)
(#35415)
- **deps**: V8: cherry-pick 717543bbf0ef (Michaël Zasso)
(#35415)
- **deps**: V8: cherry-pick 6be2f6e26e8d (Michaël Zasso)
(#35415)
- **deps**: fix V8 build issue with inline methods (Jiawen Geng)
(#35415)
- **deps**: fix platform-embedded-file-writer-win for ARM64 (Michaël
Zasso) (#35415)
- **deps**: update V8 postmortem metadata script (Colin Ihrig)
(#35415)
- **deps**: update V8 to 8.6.395 (Michaël Zasso)
(#35415)
- **deps**: upgrade npm to 7.0.0 (Myles Borins)
(#35631)
- **deps**: update npm to 7.0.0-rc.3 (Myles Borins)
(#35474)
- **deps**: V8: cherry-pick 0d6debcc5f08 (Gus Caplan)
(#33600)
- **dns**: add dns/promises alias (shisama)
(#32953)
- **doc**: move DEP0018 to End-of-Life (Rich Trott)
(#35316)
- **doc**: update support macos version for 15.x (Ash Cripps)
(#35022)
- **fs**: deprecation warning on recursive rmdir (Ian Sutherland)
(#35562)
- **fs**: reimplement read and write streams using stream.construct
(Robert Nagy) (#29656)
- **http**: fixed socket.setEncoding fatal error (iskore)
(#33405)
- **http**: emit 'error' on aborted server request (Robert Nagy)
(#33172)
- **http**: cleanup end argument handling (Robert Nagy)
(#31818)
- **http2**: allow Host in HTTP/2 requests (Alba Mendez)
(#34664)
- **http2**: add `invalidheaders` test (Pranshu Srivastava)
(#33161)
- **http2**: refactor state code validation for the http2Stream class
(rickyes) (#33535)
- **http2**: header field valid checks (Pranshu Srivastava)
(#33193)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **lib**: remove ERR\_INVALID\_OPT\_VALUE and
ERR\_INVALID\_OPT\_VALUE\_ENCODING (Denys Otrishko)
(#34682)
- **lib**: handle one of args case in ERR\_MISSING\_ARGS (Denys
Otrishko) (#34022)
- **lib**: remove NodeError from the prototype of errors with code
(Michaël Zasso) (#33857)
- **lib**: unflag AbortController (James M Snell)
(#33527)
- **lib**: initial experimental AbortController implementation (James M
Snell) (#33527)
- **net**: check args in net.connect() and socket.connect() calls
(Denys Otrishko) (#34022)
- **net**: remove long deprecated server.connections property (James M
Snell) (#33647)
- **net**: autoDestroy Socket (Robert Nagy)
(#31806)
- **process**: update v8 fast api calls usage (Maya Lekova)
(#35415)
- **process**: change default --unhandled-rejections=throw (Dan
Fabulich) (#33021)
- **process**: use v8 fast api calls for hrtime (Gus Caplan)
(#33600)
- **process**: delay throwing an error using `throwDeprecation` (Ruben
Bridgewater) (#32312)
- **repl**: remove deprecated repl.memory function (Ruben Bridgewater)
(#33286)
- **repl**: remove deprecated repl.turnOffEditorMode() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated repl.parseREPLKeyword() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated bufferedCommand property (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated .rli (Ruben Bridgewater)
(#33286)
- **src**: implement NodePlatform::PostJob (Clemens Backes)
(#35415)
- **src**: update NODE\_MODULE\_VERSION to 88 (Michaël Zasso)
(#35415)
- **src**: error reporting on CPUUsage (Yash Ladha)
(#34762)
- **src**: use node:moduleName as builtin module filename (Michaël
Zasso) (#35498)
- **src**: enable wasm trap handler on windows (Gus Caplan)
(#35033)
- **src**: update NODE\_MODULE\_VERSION to 86 (Michaël Zasso)
(#33579)
- **src**: disallow JS execution inside FreeEnvironment (Anna
Henningsen) (#33874)
- **src**: remove \_third\_party\_main support (Anna Henningsen)
(#33971)
- **src**: remove deprecated node debug command (James M Snell)
(#33648)
- **src**: remove unused CancelPendingDelayedTasks (Anna Henningsen)
(#32859)
- **stream**: try to wait for flush to complete before 'finish' (Robert
Nagy) (#34314)
- **stream**: cleanup and fix Readable.wrap (Robert Nagy)
(#34204)
- **stream**: add promises version to utility functions (rickyes)
(#33991)
- **stream**: fix writable.end callback behavior (Robert Nagy)
(#34101)
- **stream**: construct (Robert Nagy)
(#29656)
- **stream**: write should throw on unknown encoding (Robert Nagy)
(#33075)
- **stream**: fix \_final and 'prefinish' timing (Robert Nagy)
(#32780)
- **stream**: simplify Transform stream implementation (Robert Nagy)
(#32763)
- **stream**: use callback to properly propagate error (Robert Nagy)
(#29179)
- **test**: update tests after increasing typed array size to 4GB
(Kim-Anh Tran) (#35415)
- **test**: fix tests for npm 7.0.0 (Myles Borins)
(#35631)
- **test**: fix test suite to work with npm 7 (Myles Borins)
(#35474)
- **test**: update WPT harness and tests (Michaël Zasso)
(#33770)
- **timers**: introduce timers/promises (James M Snell)
(#33950)
- **tools**: disable x86 safe exception handlers in V8 (Michaël Zasso)
(#35415)
- **tools**: update V8 gypfiles for 8.6 (Ujjwal Sharma)
(#35415)
- **tools**: update V8 gypfiles for 8.5 (Ujjwal Sharma)
(#35415)
- **url**: file URL path normalization (Daijiro Wachi)
(#35477)
- **url**: verify domain is not empty after "ToASCII" (Michaël Zasso)
(#33770)
- **url**: remove U+0000 case in the fragment state (Michaël Zasso)
(#33770)
- **url**: remove gopher from special schemes (Michaël Zasso)
(#33325)
- **url**: forbid lt and gt in url host code point (Yash Ladha)
(#33328)
- **util**: change default value of `maxStringLength` to 10000
(unknown) (#32744)
- **wasi**: drop --experimental-wasm-bigint requirement (Colin Ihrig)
(#35415)
- **win, child_process**: sanitize env variables (Bartosz Sosnowski)
(#35210)
- **worker**: make MessageEvent class more Web-compatible (Anna
Henningsen) (#35496)
- **worker**: set trackUnmanagedFds to true by default (Anna
Henningsen) (#34394)
- **worker**: rename error code to be more accurate (Anna Henningsen)
(#33872)

PR-URL: #35014
BethGriggs added a commit that referenced this pull request Oct 20, 2020
Notable changes:

Deprecations and Removals:

- **build**: remove --build-v8-with-gn configure option (Yang Guo)
(#27576)
- **build**: drop support for VS2017 (Michaël Zasso)
(#33694)
- **doc**: move DEP0018 to End-of-Life (Rich Trott)
(#35316)
- **fs**: deprecation warning on recursive rmdir (Ian Sutherland)
(#35562)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **net**: remove long deprecated server.connections property (James M
Snell) (#33647)
- **repl**: remove deprecated repl.memory function (Ruben Bridgewater)
(#33286)
- **repl**: remove deprecated repl.turnOffEditorMode() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated repl.parseREPLKeyword() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated bufferedCommand property (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated .rli (Ruben Bridgewater)
(#33286)
- **src**: remove deprecated node debug command (James M Snell)
(#33648)
- **timers**: introduce timers/promises (James M Snell)
(#33950)
- **util**: change default value of `maxStringLength` to 10000
(unknown) (#32744)
- **wasi**: drop --experimental-wasm-bigint requirement (Colin Ihrig)
(#35415)

npm 7 (#35631):

Node.js 15 comes with a new major release of npm, npm 7. npm 7 comes
with many new features - including npm workspaces and a new
package-lock.json format. npm 7 also includes yarn.lock file support.
One of the big changes in npm 7 is that peer dependencies are now
installed by default.

Throw On Unhandled Rejections
(#33021):

As of Node.js 15, the default mode for `unhandledRejection` is changed
to `throw` (from `warn`). In `throw` mode, if an `unhandledRejection`
hook is not set, the `unhandledRejection` is raised as an uncaught
exception. Users that have an `unhandledRejection` hook should see no
change in behavior, and it’s still possible to switch modes using the
`--unhandled-rejections=mode` process flag.

QUIC (#32379):

Node.js 15 comes with experimental support QUIC, which can be enabled
by compiling Node.js with the `--experimental-quic` configuration flag.
The Node.js QUIC implementation is exposed by the core `net` module.

V8 8.6 (#35415):

The V8 JavaScript engine has been updated to V8 8.6 (V8 8.4 is the
latest available in Node.js 14). Along with performance tweaks and
improvements the V8 update also brings the following language features:
* `Promise.any()` (from V8 8.5)
* `AggregateError` (from V8 8.5)
* `String.prototype.replaceAll()` (from V8 8.5)
* Logical assignment operators `&&=`, `||=`, and `??=` (from V8 8.5)

Other Notable Changes:

- **assert**: add `assert/strict` alias module (ExE Boss)
(#34001)
- **dns**: add dns/promises alias (shisama)
(#32953)
- **fs**: reimplement read and write streams using stream.construct
(Robert Nagy) (#29656)
- **http2**: allow Host in HTTP/2 requests (Alba Mendez)
(#34664)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **lib**: unflag AbortController (James M Snell)
(#33527)
- **lib**: initial experimental AbortController implementation (James M
Snell) (#33527)
- **net**: autoDestroy Socket (Robert Nagy)
(#31806)
- **src**: disallow JS execution inside FreeEnvironment (Anna
Henningsen) (#33874)
- **stream**: construct (Robert Nagy)
(#29656)
- **worker**: make MessageEvent class more Web-compatible (Anna
Henningsen) (#35496)

Semver-Major Commits:

- **assert**: add `assert/strict` alias module (ExE Boss)
(#34001)
- **build**: reset embedder string to "-node.0" (Michaël Zasso)
(#35415)
- **build**: remove --build-v8-with-gn configure option (Yang Guo)
(#27576)
- **build**: drop support for VS2017 (Michaël Zasso)
(#33694)
- **crypto**: refactoring internals, add WebCrypto (James M Snell)
(#35093)
- **crypto**: move node\_crypto files to src/crypto (James M Snell)
(#35093)
- **deps**: V8: cherry-pick d76abfed3512 (Michaël Zasso)
(#35415)
- **deps**: V8: cherry-pick 717543bbf0ef (Michaël Zasso)
(#35415)
- **deps**: V8: cherry-pick 6be2f6e26e8d (Michaël Zasso)
(#35415)
- **deps**: fix V8 build issue with inline methods (Jiawen Geng)
(#35415)
- **deps**: fix platform-embedded-file-writer-win for ARM64 (Michaël
Zasso) (#35415)
- **deps**: update V8 postmortem metadata script (Colin Ihrig)
(#35415)
- **deps**: update V8 to 8.6.395 (Michaël Zasso)
(#35415)
- **deps**: upgrade npm to 7.0.0 (Myles Borins)
(#35631)
- **deps**: update npm to 7.0.0-rc.3 (Myles Borins)
(#35474)
- **deps**: V8: cherry-pick 0d6debcc5f08 (Gus Caplan)
(#33600)
- **dns**: add dns/promises alias (shisama)
(#32953)
- **doc**: move DEP0018 to End-of-Life (Rich Trott)
(#35316)
- **doc**: update support macos version for 15.x (Ash Cripps)
(#35022)
- **fs**: deprecation warning on recursive rmdir (Ian Sutherland)
(#35562)
- **fs**: reimplement read and write streams using stream.construct
(Robert Nagy) (#29656)
- **http**: fixed socket.setEncoding fatal error (iskore)
(#33405)
- **http**: emit 'error' on aborted server request (Robert Nagy)
(#33172)
- **http**: cleanup end argument handling (Robert Nagy)
(#31818)
- **http2**: allow Host in HTTP/2 requests (Alba Mendez)
(#34664)
- **http2**: add `invalidheaders` test (Pranshu Srivastava)
(#33161)
- **http2**: refactor state code validation for the http2Stream class
(rickyes) (#33535)
- **http2**: header field valid checks (Pranshu Srivastava)
(#33193)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **lib**: remove ERR\_INVALID\_OPT\_VALUE and
ERR\_INVALID\_OPT\_VALUE\_ENCODING (Denys Otrishko)
(#34682)
- **lib**: handle one of args case in ERR\_MISSING\_ARGS (Denys
Otrishko) (#34022)
- **lib**: remove NodeError from the prototype of errors with code
(Michaël Zasso) (#33857)
- **lib**: unflag AbortController (James M Snell)
(#33527)
- **lib**: initial experimental AbortController implementation (James M
Snell) (#33527)
- **net**: check args in net.connect() and socket.connect() calls
(Denys Otrishko) (#34022)
- **net**: remove long deprecated server.connections property (James M
Snell) (#33647)
- **net**: autoDestroy Socket (Robert Nagy)
(#31806)
- **process**: update v8 fast api calls usage (Maya Lekova)
(#35415)
- **process**: change default --unhandled-rejections=throw (Dan
Fabulich) (#33021)
- **process**: use v8 fast api calls for hrtime (Gus Caplan)
(#33600)
- **process**: delay throwing an error using `throwDeprecation` (Ruben
Bridgewater) (#32312)
- **repl**: remove deprecated repl.memory function (Ruben Bridgewater)
(#33286)
- **repl**: remove deprecated repl.turnOffEditorMode() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated repl.parseREPLKeyword() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated bufferedCommand property (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated .rli (Ruben Bridgewater)
(#33286)
- **src**: implement NodePlatform::PostJob (Clemens Backes)
(#35415)
- **src**: update NODE\_MODULE\_VERSION to 88 (Michaël Zasso)
(#35415)
- **src**: error reporting on CPUUsage (Yash Ladha)
(#34762)
- **src**: use node:moduleName as builtin module filename (Michaël
Zasso) (#35498)
- **src**: enable wasm trap handler on windows (Gus Caplan)
(#35033)
- **src**: update NODE\_MODULE\_VERSION to 86 (Michaël Zasso)
(#33579)
- **src**: disallow JS execution inside FreeEnvironment (Anna
Henningsen) (#33874)
- **src**: remove \_third\_party\_main support (Anna Henningsen)
(#33971)
- **src**: remove deprecated node debug command (James M Snell)
(#33648)
- **src**: remove unused CancelPendingDelayedTasks (Anna Henningsen)
(#32859)
- **stream**: try to wait for flush to complete before 'finish' (Robert
Nagy) (#34314)
- **stream**: cleanup and fix Readable.wrap (Robert Nagy)
(#34204)
- **stream**: add promises version to utility functions (rickyes)
(#33991)
- **stream**: fix writable.end callback behavior (Robert Nagy)
(#34101)
- **stream**: construct (Robert Nagy)
(#29656)
- **stream**: write should throw on unknown encoding (Robert Nagy)
(#33075)
- **stream**: fix \_final and 'prefinish' timing (Robert Nagy)
(#32780)
- **stream**: simplify Transform stream implementation (Robert Nagy)
(#32763)
- **stream**: use callback to properly propagate error (Robert Nagy)
(#29179)
- **test**: update tests after increasing typed array size to 4GB
(Kim-Anh Tran) (#35415)
- **test**: fix tests for npm 7.0.0 (Myles Borins)
(#35631)
- **test**: fix test suite to work with npm 7 (Myles Borins)
(#35474)
- **test**: update WPT harness and tests (Michaël Zasso)
(#33770)
- **timers**: introduce timers/promises (James M Snell)
(#33950)
- **tools**: disable x86 safe exception handlers in V8 (Michaël Zasso)
(#35415)
- **tools**: update V8 gypfiles for 8.6 (Ujjwal Sharma)
(#35415)
- **tools**: update V8 gypfiles for 8.5 (Ujjwal Sharma)
(#35415)
- **url**: file URL path normalization (Daijiro Wachi)
(#35477)
- **url**: verify domain is not empty after "ToASCII" (Michaël Zasso)
(#33770)
- **url**: remove U+0000 case in the fragment state (Michaël Zasso)
(#33770)
- **url**: remove gopher from special schemes (Michaël Zasso)
(#33325)
- **url**: forbid lt and gt in url host code point (Yash Ladha)
(#33328)
- **util**: change default value of `maxStringLength` to 10000
(unknown) (#32744)
- **wasi**: drop --experimental-wasm-bigint requirement (Colin Ihrig)
(#35415)
- **win, child_process**: sanitize env variables (Bartosz Sosnowski)
(#35210)
- **worker**: make MessageEvent class more Web-compatible (Anna
Henningsen) (#35496)
- **worker**: set trackUnmanagedFds to true by default (Anna
Henningsen) (#34394)
- **worker**: rename error code to be more accurate (Anna Henningsen)
(#33872)

PR-URL: #35014
BethGriggs added a commit that referenced this pull request Oct 20, 2020
Notable changes:

Deprecations and Removals:

- **build**: remove --build-v8-with-gn configure option (Yang Guo)
(#27576)
- **build**: drop support for VS2017 (Michaël Zasso)
(#33694)
- **doc**: move DEP0018 to End-of-Life (Rich Trott)
(#35316)
- **fs**: deprecation warning on recursive rmdir (Ian Sutherland)
(#35562)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **net**: remove long deprecated server.connections property (James M
Snell) (#33647)
- **repl**: remove deprecated repl.memory function (Ruben Bridgewater)
(#33286)
- **repl**: remove deprecated repl.turnOffEditorMode() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated repl.parseREPLKeyword() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated bufferedCommand property (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated .rli (Ruben Bridgewater)
(#33286)
- **src**: remove deprecated node debug command (James M Snell)
(#33648)
- **timers**: introduce timers/promises (James M Snell)
(#33950)
- **util**: change default value of `maxStringLength` to 10000
(unknown) (#32744)
- **wasi**: drop --experimental-wasm-bigint requirement (Colin Ihrig)
(#35415)

npm 7 (#35631):

Node.js 15 comes with a new major release of npm, npm 7. npm 7 comes
with many new features - including npm workspaces and a new
package-lock.json format. npm 7 also includes yarn.lock file support.
One of the big changes in npm 7 is that peer dependencies are now
installed by default.

Throw On Unhandled Rejections
(#33021):

As of Node.js 15, the default mode for `unhandledRejection` is changed
to `throw` (from `warn`). In `throw` mode, if an `unhandledRejection`
hook is not set, the `unhandledRejection` is raised as an uncaught
exception. Users that have an `unhandledRejection` hook should see no
change in behavior, and it’s still possible to switch modes using the
`--unhandled-rejections=mode` process flag.

QUIC (#32379):

Node.js 15 comes with experimental support QUIC, which can be enabled
by compiling Node.js with the `--experimental-quic` configuration flag.
The Node.js QUIC implementation is exposed by the core `net` module.

V8 8.6 (#35415):

The V8 JavaScript engine has been updated to V8 8.6 (V8 8.4 is the
latest available in Node.js 14). Along with performance tweaks and
improvements the V8 update also brings the following language features:
* `Promise.any()` (from V8 8.5)
* `AggregateError` (from V8 8.5)
* `String.prototype.replaceAll()` (from V8 8.5)
* Logical assignment operators `&&=`, `||=`, and `??=` (from V8 8.5)

Other Notable Changes:

- **assert**: add `assert/strict` alias module (ExE Boss)
(#34001)
- **dns**: add dns/promises alias (shisama)
(#32953)
- **fs**: reimplement read and write streams using stream.construct
(Robert Nagy) (#29656)
- **http2**: allow Host in HTTP/2 requests (Alba Mendez)
(#34664)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **lib**: unflag AbortController (James M Snell)
(#33527)
- **lib**: initial experimental AbortController implementation (James M
Snell) (#33527)
- **net**: autoDestroy Socket (Robert Nagy)
(#31806)
- **src**: disallow JS execution inside FreeEnvironment (Anna
Henningsen) (#33874)
- **stream**: construct (Robert Nagy)
(#29656)
- **worker**: make MessageEvent class more Web-compatible (Anna
Henningsen) (#35496)

Semver-Major Commits:

- **assert**: add `assert/strict` alias module (ExE Boss)
(#34001)
- **build**: reset embedder string to "-node.0" (Michaël Zasso)
(#35415)
- **build**: remove --build-v8-with-gn configure option (Yang Guo)
(#27576)
- **build**: drop support for VS2017 (Michaël Zasso)
(#33694)
- **crypto**: refactoring internals, add WebCrypto (James M Snell)
(#35093)
- **crypto**: move node\_crypto files to src/crypto (James M Snell)
(#35093)
- **deps**: V8: cherry-pick d76abfed3512 (Michaël Zasso)
(#35415)
- **deps**: V8: cherry-pick 717543bbf0ef (Michaël Zasso)
(#35415)
- **deps**: V8: cherry-pick 6be2f6e26e8d (Michaël Zasso)
(#35415)
- **deps**: fix V8 build issue with inline methods (Jiawen Geng)
(#35415)
- **deps**: fix platform-embedded-file-writer-win for ARM64 (Michaël
Zasso) (#35415)
- **deps**: update V8 postmortem metadata script (Colin Ihrig)
(#35415)
- **deps**: update V8 to 8.6.395 (Michaël Zasso)
(#35415)
- **deps**: upgrade npm to 7.0.0 (Myles Borins)
(#35631)
- **deps**: update npm to 7.0.0-rc.3 (Myles Borins)
(#35474)
- **deps**: V8: cherry-pick 0d6debcc5f08 (Gus Caplan)
(#33600)
- **dns**: add dns/promises alias (shisama)
(#32953)
- **doc**: move DEP0018 to End-of-Life (Rich Trott)
(#35316)
- **doc**: update support macos version for 15.x (Ash Cripps)
(#35022)
- **fs**: deprecation warning on recursive rmdir (Ian Sutherland)
(#35562)
- **fs**: reimplement read and write streams using stream.construct
(Robert Nagy) (#29656)
- **http**: fixed socket.setEncoding fatal error (iskore)
(#33405)
- **http**: emit 'error' on aborted server request (Robert Nagy)
(#33172)
- **http**: cleanup end argument handling (Robert Nagy)
(#31818)
- **http2**: allow Host in HTTP/2 requests (Alba Mendez)
(#34664)
- **http2**: add `invalidheaders` test (Pranshu Srivastava)
(#33161)
- **http2**: refactor state code validation for the http2Stream class
(rickyes) (#33535)
- **http2**: header field valid checks (Pranshu Srivastava)
(#33193)
- **lib**: add EventTarget-related browser globals (Anna Henningsen)
(#35496)
- **lib**: remove ERR\_INVALID\_OPT\_VALUE and
ERR\_INVALID\_OPT\_VALUE\_ENCODING (Denys Otrishko)
(#34682)
- **lib**: handle one of args case in ERR\_MISSING\_ARGS (Denys
Otrishko) (#34022)
- **lib**: remove NodeError from the prototype of errors with code
(Michaël Zasso) (#33857)
- **lib**: unflag AbortController (James M Snell)
(#33527)
- **lib**: initial experimental AbortController implementation (James M
Snell) (#33527)
- **net**: check args in net.connect() and socket.connect() calls
(Denys Otrishko) (#34022)
- **net**: remove long deprecated server.connections property (James M
Snell) (#33647)
- **net**: autoDestroy Socket (Robert Nagy)
(#31806)
- **process**: update v8 fast api calls usage (Maya Lekova)
(#35415)
- **process**: change default --unhandled-rejections=throw (Dan
Fabulich) (#33021)
- **process**: use v8 fast api calls for hrtime (Gus Caplan)
(#33600)
- **process**: delay throwing an error using `throwDeprecation` (Ruben
Bridgewater) (#32312)
- **repl**: remove deprecated repl.memory function (Ruben Bridgewater)
(#33286)
- **repl**: remove deprecated repl.turnOffEditorMode() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated repl.parseREPLKeyword() function (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated bufferedCommand property (Ruben
Bridgewater) (#33286)
- **repl**: remove deprecated .rli (Ruben Bridgewater)
(#33286)
- **src**: implement NodePlatform::PostJob (Clemens Backes)
(#35415)
- **src**: update NODE\_MODULE\_VERSION to 88 (Michaël Zasso)
(#35415)
- **src**: error reporting on CPUUsage (Yash Ladha)
(#34762)
- **src**: use node:moduleName as builtin module filename (Michaël
Zasso) (#35498)
- **src**: enable wasm trap handler on windows (Gus Caplan)
(#35033)
- **src**: update NODE\_MODULE\_VERSION to 86 (Michaël Zasso)
(#33579)
- **src**: disallow JS execution inside FreeEnvironment (Anna
Henningsen) (#33874)
- **src**: remove \_third\_party\_main support (Anna Henningsen)
(#33971)
- **src**: remove deprecated node debug command (James M Snell)
(#33648)
- **src**: remove unused CancelPendingDelayedTasks (Anna Henningsen)
(#32859)
- **stream**: try to wait for flush to complete before 'finish' (Robert
Nagy) (#34314)
- **stream**: cleanup and fix Readable.wrap (Robert Nagy)
(#34204)
- **stream**: add promises version to utility functions (rickyes)
(#33991)
- **stream**: fix writable.end callback behavior (Robert Nagy)
(#34101)
- **stream**: construct (Robert Nagy)
(#29656)
- **stream**: write should throw on unknown encoding (Robert Nagy)
(#33075)
- **stream**: fix \_final and 'prefinish' timing (Robert Nagy)
(#32780)
- **stream**: simplify Transform stream implementation (Robert Nagy)
(#32763)
- **stream**: use callback to properly propagate error (Robert Nagy)
(#29179)
- **test**: update tests after increasing typed array size to 4GB
(Kim-Anh Tran) (#35415)
- **test**: fix tests for npm 7.0.0 (Myles Borins)
(#35631)
- **test**: fix test suite to work with npm 7 (Myles Borins)
(#35474)
- **test**: update WPT harness and tests (Michaël Zasso)
(#33770)
- **timers**: introduce timers/promises (James M Snell)
(#33950)
- **tools**: disable x86 safe exception handlers in V8 (Michaël Zasso)
(#35415)
- **tools**: update V8 gypfiles for 8.6 (Ujjwal Sharma)
(#35415)
- **tools**: update V8 gypfiles for 8.5 (Ujjwal Sharma)
(#35415)
- **url**: file URL path normalization (Daijiro Wachi)
(#35477)
- **url**: verify domain is not empty after "ToASCII" (Michaël Zasso)
(#33770)
- **url**: remove U+0000 case in the fragment state (Michaël Zasso)
(#33770)
- **url**: remove gopher from special schemes (Michaël Zasso)
(#33325)
- **url**: forbid lt and gt in url host code point (Yash Ladha)
(#33328)
- **util**: change default value of `maxStringLength` to 10000
(unknown) (#32744)
- **wasi**: drop --experimental-wasm-bigint requirement (Colin Ihrig)
(#35415)
- **win, child_process**: sanitize env variables (Bartosz Sosnowski)
(#35210)
- **worker**: make MessageEvent class more Web-compatible (Anna
Henningsen) (#35496)
- **worker**: set trackUnmanagedFds to true by default (Anna
Henningsen) (#34394)
- **worker**: rename error code to be more accurate (Anna Henningsen)
(#33872)

PR-URL: #35014
@luiscastro193
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luiscastro193 commented Nov 25, 2020

For all the folks who, like me, prefer the behaviour to be more consistent with the browser ecosystem, I recommend the following line:

process.on('unhandledRejection', reason => console.trace(reason));

@Fishrock123
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Contributor

Fishrock123 commented Nov 25, 2020

I believe that is similar to setting --unhandled-rejections=warn, which can also be set via the NODE_OPTIONS environment variable.

@benjamingr
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Member

@luiscastro193 note that in order to be consistent with browsers it is sufficient to do process.on('uncaughtException', reason => console.trace(reason)); since I believe unhandled rejections end up as uncaught exceptions.

Also note that the default changed because not terminating the process is unsafe and leads to possible cascading failures - so beware dragons ahead.

@mmarchini
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Contributor

It's worth noting that console.trace will add frames to the stacktrace which are unrelated to where the rejection happened, which might be undesired behavior to some users:

$ node -e 'process.on("unhandledRejection", function iShouldntShowOnStackTraceYetHereIAm(e) { console.trace(e) }); function foo() { Promise.reject(new Error()) } foo()'
Trace: Error
    at foo ([eval]:1:137)
    at [eval]:1:152
    at Script.runInThisContext (vm.js:120:18)
    at Object.runInThisContext (vm.js:309:38)
    at Object.<anonymous> ([eval]-wrapper:10:26)
    at Module._compile (internal/modules/cjs/loader.js:1015:30)
    at evalScript (internal/process/execution.js:94:25)
    at internal/main/eval_string.js:23:3
    at process.iShouldntShowOnStackTraceYetHereIAm ([eval]:1:92)
    at process.emit (events.js:314:20)
    at processPromiseRejections (internal/process/promises.js:209:33)
    at processTicksAndRejections (internal/process/task_queues.js:98:32)

console.warn might be a better option for most users:

$ node -e 'process.on("unhandledRejection", function iShouldntShowOnStackTraceYetHereIAm(e) { console.warn(e) }); function foo() { Promise.reject(new Error()) } foo()'
Error
    at foo ([eval]:1:136)
    at [eval]:1:151
    at Script.runInThisContext (vm.js:120:18)
    at Object.runInThisContext (vm.js:309:38)
    at Object.<anonymous> ([eval]-wrapper:10:26)
    at Module._compile (internal/modules/cjs/loader.js:1015:30)
    at evalScript (internal/process/execution.js:94:25)
    at internal/main/eval_string.js:23:3

joesepi pushed a commit to joesepi/node that referenced this pull request Jan 8, 2021
This is a semver-major change that resolves DEP0018.

All users that have set an unhandledRejection hook or set a non-default
value for the --unhandled-rejections flag will see no change in behavior
after this change.

Refs: https://nodejs.org/dist/latest/docs/api/deprecations.html#deprecations_dep0018_unhandled_promise_rejections

PR-URL: nodejs#33021
Fixes: nodejs#20392
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Mary Marchini <oss@mmarchini.me>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
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Terminate process on unhandled promise rejection