1544976 - Quick teardown of workers causes Debugger to fail loading

Status: RESOLVED FIXED

(DevTools :: Debugger, defect, P2)

Description

[:Harald Kirschner :digitarald]

What were you doing?

1. Open Debugger on https://worker-teardown.glitch.me/

What happened?

Debugger doesn't load, stays gray.

What should have happened?

Debugger loads.

Anything else we should know?

Flurry of 1 error and 2 types of warnings keeps showing up in Browser Console:

Error while detaching the thread front: No such actor for ID: server1.conn1.child1/workerTarget1064/context1 target-mixin.js:555:21
Handler function DebuggerClient.requester threw an exception: Error: resume command sent while not paused. Currently attached
Stack: _assertPaused@resource://devtools/shared/client/thread-client.js:55:13
before@resource://devtools/shared/client/thread-client.js:80:12
DebuggerClient.requester/<@resource://devtools/shared/client/debugger-client.js:103:31
exports.makeInfallible/<@resource://devtools/shared/ThreadSafeDevToolsUtils.js:109:22
resume@resource://devtools/shared/client/thread-client.js:122:17
updateWorkerClients@resource://devtools/client/debugger/src/client/firefox/workers.js:42:20
Line: 55, column: 13 ThreadSafeDevToolsUtils.js:88:13

Error while detaching target: undefined target-mixin.js:547:21

Error while detaching the thread front: No such actor for ID: server1.conn1.child1/workerTarget1070/context1 target-mixin.js:555:21

Comment 1

[Jason Laster [:jlast]]

Brian, could you take a look at this?

Comment 2

[Brian Hackett [Laid off!]]

I'll look into fixing the error messages, but I see these in the usual case when closing a page with workers or after a worker is terminated, and they don't necessarily indicate a problem.

The debugger loads fine on the page for me, though. Does this still happen for you on tip? Can you paste a complete log from the browser console or from running firefox from a terminal (the errors should be printed to stderr).

Comment 3

[:Harald Kirschner :digitarald]

It isn't easy reproduce it with the example now. It worked for me 3 times and I had to re-open Debugger once to hit it.

Another sign that the Debugger stopped working is that it does load the Debugger but doesn't show Threads anymore. Browser Console warnings for this case were:

Error while detaching the thread front: 'detach' request packet to 'server1.conn9.child1/context17' can't be sent as the connection is closed. target-mixin.js:555:21
Error while detaching target: undefined target-mixin.js:547:21
Error while detaching the thread front: No such actor for ID: server1.conn10.child1/workerTarget47/context1 target-mixin.js:555:21
Error while detaching target: undefined 2 target-mixin.js:547:21
Error while detaching target: undefined 2 target-mixin.js:547:21
Error while detaching the thread front: No such actor for ID: server1.conn10.child1/workerTarget49/context1 target-mixin.js:555:21
Error while detaching the thread front: No such actor for ID: server1.conn10.child1/workerTarget50/context1 target-mixin.js:555:21
Error while detaching the thread front: No such actor for ID: server1.conn10.child1/workerTarget48/context1 target-mixin.js:555:21
Error while detaching the thread front: No such actor for ID: server1.conn10.child1/workerTarget54/context1 target-mixin.js:555:21
Error while detaching the thread front: 'detach' request packet to 'server1.conn10.child1/context17' can't be sent as the connection is closed. target-mixin.js:555:21

Have to reproduce on a fresh profile to get the stderr.

Comment 4

[Brian Hackett [Laid off!]]

Attachment: Bug 1544976 Part 1 - Ignore exceptions thrown while attaching to worker threads, r=loganfsmyth.

Depends on D28931

Comment 5

[Brian Hackett [Laid off!]]

Attachment: Bug 1544976 Part 2 - Add devtools.debugger.quiet quiet pref to suppress warnings from protocol errors, r=loganfsmyth.

Depends on D28932

Comment 6

[Brian Hackett [Laid off!]]

OK, thanks, I was able to reproduce this by tweaking the test case to create/destroy workers more frequently. The messages above are all just noise, actually, and printed out when we successfully recover from a protocol error due to a terminated worker thread. Part 2 adds a preference to stop printing those. The actual problem was due to a promise rejection after receiving an error from the server in debugger-client.js, and either wasn't being printed at all or was being printed as a very subtle console.error() call. I'd like to understand sometime why we don't print out these unhandled rejections, because they are a leading cause of debugger breakage in my experience.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/1ebc89e3ad97
Part 1 - Ignore exceptions thrown while attaching to worker threads, r=loganfsmyth.
https://hg.mozilla.org/integration/mozilla-inbound/rev/30b551b1a212
Part 2 - Add devtools.debugger.quiet quiet pref to suppress warnings from protocol errors, r=loganfsmyth.

Comment 8

[Pulsebot]

Backout by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/618d85aa18ee
Backed out 2 changesets for causing xpcshell failures in devtools/client/memory/test/unit/test_action_diffing_02.js

Comment 9

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/1ebc89e3ad97
https://hg.mozilla.org/mozilla-central/rev/30b551b1a212

Comment 10

[Pulsebot]

Backout by [e-mail]:
https://hg.mozilla.org/mozilla-central/rev/53014805c60b
Backed out 2 changesets for causing xpcshell failures in devtools/client/memory/test/unit/test_action_diffing_02.js. a=backout

Comment 11

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

This got backed out:

https://hg.mozilla.org/integration/mozilla-inbound/rev/618d85aa18ee8402d69354e4980939fb89521436

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=mozilla-inbound&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Crunnable&group_state=expanded&revision=30b551b1a2122b0c4478b3eeb790a96204d4cfcf

Check the XPCshell (X) and devtools (dt) failures.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/26916fd0f252
Ignore exceptions thrown while attaching to worker threads, r=loganfsmyth.

Comment 13

[Raul Gurzau (:RaulG)]

https://hg.mozilla.org/mozilla-central/rev/26916fd0f252

Comment 14

[Brian Hackett [Laid off!]]

I didn't land the pref here because it caused some weird xpcshell failures and I wasn't feeling very motivated to figure them out.

Comment 15

[Cristian Fogel [:cfogel]]

Attachment: debugerCrrashMe.gif

In an attempt to verify the fix, I was able to reproduce with 67.0.4 after spamming the open/close DevTools key (F12) with the Debugger tab in focus.

After a quick check with 68.0b13, 69.0a1 (2019-06-30) there was a different behavior as per the description, the whole tab crashed.
Adding a recording with this comment and will post the log bellow.

Comment 16

[Cristian Fogel [:cfogel]]

Attachment: log.txt

@Brian, mind taking a look at this as well?
Is it something that needs to be filed separately or part of the fails mentioned in comment #14?

Thank you!

Comment 17

[Cristian Fogel [:cfogel]]

Attachment: log.txt

Comment 18

[Brian Hackett [Laid off!]]

Sorry for the late reply. The errors in the log are pretty innocuous, those are often printed if the devtools shut down while user interactions are still being handled. Did you get a crash report for the tab crash?

Comment 19

[Cristian Fogel [:cfogel]]

https://crash-stats.mozilla.org/report/index/134abe8c-a599-4be0-8bab-9d8660190805

Hope this helps.