Ensure clean shutdown of JS threads #27016

gterzian · 2020-06-22T06:07:17Z

FIX #26685
FIX #26996
FIX #9672
FIX #27027

./mach build -d does not report any errors
./mach test-tidy does not report any errors
These changes fix #___ (GitHub issue number if applicable)

There are tests for these changes OR
These changes do not require tests because ___

highfive · 2020-06-22T06:07:22Z

Heads up! This PR modifies the following files:

@asajeffrey: components/constellation/constellation.rs
@cbrewster: components/constellation/constellation.rs

gterzian · 2020-06-22T06:07:43Z

@bors-servo try=wpt

bors-servo · 2020-06-22T06:07:49Z

⌛ Trying commit 91c6c42 with merge dee9465...

constellation: don't make shutdown depend on having exited all pipelines  FIX #26685 FIX #26996 ---  - [ ] `./mach build -d` does not report any errors - [ ] `./mach test-tidy` does not report any errors - [ ] These changes fix #___ (GitHub issue number if applicable)  - [ ] There are tests for these changes OR - [ ] These changes do not require tests because ___

gterzian · 2020-06-22T06:30:22Z

@bors-servo try=wpt

bors-servo · 2020-06-22T06:30:27Z

⌛ Trying commit 0d4c16c with merge 019ac56...

Constellation: don't make shutdown depend on having exited all pipelines  FIX #26685 FIX #26996 FIX #9672 ---  - [ ] `./mach build -d` does not report any errors - [ ] `./mach test-tidy` does not report any errors - [ ] These changes fix #___ (GitHub issue number if applicable)  - [ ] There are tests for these changes OR - [ ] These changes do not require tests because ___

paulrouget · 2020-06-22T06:56:36Z

components/constellation/constellation.rs

            // Randomly close a pipeline if --random-pipeline-closure-probability is set
            // This is for testing the hardening of the constellation.
            self.maybe_close_random_pipeline();
            self.handle_request();
        }
+
+        // Try to cleanly exit all pipelines, until a timeout hits.
+        let pipeline_exit_timeout = after(Duration::from_millis(200));


If possible, can you make that a pref?

paulrouget · 2020-06-22T06:56:39Z

components/constellation/constellation.rs

+        loop {
+            if self.pipelines.is_empty() {
+                break;
+            }


This loop + if could be turned into a while.

paulrouget · 2020-06-22T06:56:58Z

components/constellation/constellation.rs

+                recv(pipeline_exit_timeout) -> _ => {
+                    if !self.pipelines.is_empty() {
+                        warn!("Failed to exit a number of pipelines {:?}", self.pipelines.len());
+                    }


Is there any way to get more information about why it's blocked?

I'm afraid we will have that warning and never pay attention to it.

Maybe make it an error, or dump a stack, not sure…

I tried sampling them via the BHM, and while it works it's a bit messy because the bhm messaging stuff is not really setup for that, I think it could potentially introduce a new hang since we don't match bhm senders to pipeline yet(so the constellation could end-up blocking on a receiver for an already exited pipeline if not careful), so perhaps best done as a follow-up, if at all.

Also someone could use the dedicated sampling API to do this manually in some way, the current changes are more aimed at ensuring the window actually closes when someone wants to close it.

Also this seems to mostly happen when JS is running and blocking the script-thread from handling the exit messages, so I think what we really need is a hook to kill the script-thread, see #27027

bors-servo · 2020-06-22T07:26:42Z

💔 Test failed - status-taskcluster

gterzian · 2020-06-22T14:24:34Z

@paulrouget r?

gterzian · 2020-06-23T05:01:42Z

Ok actually I will do this "properly" as per #27027, and remove the timeout since that doesn't actually solve the underlying problem...

gterzian · 2020-06-30T04:36:01Z

@bors-servo r=jdm,paulrouget

bors-servo · 2020-06-30T04:36:02Z

📌 Commit f083da4 has been approved by jdm,paulrouget

Ensure clean shutdown of JS threads  FIX #26685 FIX #26996 FIX #9672 FIX #27027 ---  - [ ] `./mach build -d` does not report any errors - [ ] `./mach test-tidy` does not report any errors - [ ] These changes fix #___ (GitHub issue number if applicable)  - [ ] There are tests for these changes OR - [ ] These changes do not require tests because ___

bors-servo · 2020-06-30T04:36:08Z

⌛ Testing commit f083da4 with merge 9fb1a96...

bors-servo · 2020-06-30T05:13:29Z

💔 Test failed - status-taskcluster

gterzian · 2020-06-30T05:18:56Z

  ▶ TIMEOUT [expected PASS] /_mozilla/mozilla/worklets/test_paint_worklet.html
  │ 
  │ error: XDG_RUNTIME_DIR not set in the environment.
  │ libEGL warning: No hardware driver found, falling back to software rendering
  │ internal error: entered unreachable code (thread <unnamed>, at components/script/dom/globalscope.rs:2733)
  │    0: servo::backtrace::print
  │    1: servo::main::{{closure}}
  │    2: std::panicking::rust_panic_with_hook
  │              at /rustc/a8cf3991177f30694200002cd9479ffbbe6d9a1a/src/libstd/panicking.rs:477
  │    3: std::panicking::begin_panic
  │    4: script::dom::globalscope::GlobalScope::can_continue_running
  │    5: script::dom::globalscope::GlobalScope::perform_a_microtask_checkpoint
  │    6: <script::dom::bindings::settings_stack::AutoEntryScript as core::ops::drop::Drop>::drop
  │    7: profile_traits::time::profile
  │    8: script::dom::globalscope::GlobalScope::evaluate_script_on_global_with_result
  │    9: script::dom::workletglobalscope::WorkletGlobalScope::evaluate_js
  │   10: script::dom::worklet::WorkletThread::process_control
  │   11: script::dom::worklet::WorkletThread::run
  │   12: std::sys_common::backtrace::__rust_begin_short_backtrace
  │   13: core::ops::function::FnOnce::call_once{{vtable.shim}}
  │   14: <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
  │              at /rustc/a8cf3991177f30694200002cd9479ffbbe6d9a1a/src/liballoc/boxed.rs:1076
  │       <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
  │              at /rustc/a8cf3991177f30694200002cd9479ffbbe6d9a1a/src/liballoc/boxed.rs:1076
  │       std::sys::unix::thread::Thread::new::thread_start
  │              at /rustc/a8cf3991177f30694200002cd9479ffbbe6d9a1a/src/libstd/sys/unix/thread.rs:87
  │   15: start_thread
  │   16: __clone
  └ [2020-06-30T05:11:54Z ERROR servo] internal error: entered unreachable code

Ok, didn't account for worklets...

gterzian · 2020-06-30T06:06:52Z

@bors-servo r=jdm,paulrouget

bors-servo · 2020-06-30T06:06:53Z

📌 Commit 44ebca7 has been approved by jdm,paulrouget

bors-servo · 2020-06-30T06:07:01Z

⌛ Testing commit 44ebca7 with merge b9404fc...

bors-servo · 2020-06-30T07:13:02Z

☀️ Test successful - status-taskcluster
Approved by: jdm,paulrouget
Pushing b9404fc to master...

highfive assigned ferjm Jun 22, 2020

highfive added the S-awaiting-review label Jun 22, 2020

gterzian changed the title ~~constellation: don't make shutdown depend on having exited all pipelines~~ Constellation: don't make shutdown depend on having exited all pipelines Jun 22, 2020

gterzian force-pushed the fix_closing_window branch from 91c6c42 to 0d4c16c Compare Jun 22, 2020

paulrouget reviewed Jun 22, 2020

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highfive added the S-tests-failed label Jun 22, 2020

gterzian mentioned this pull request Jun 22, 2020

Use BHM to terminate hanging JS threads when closing window #27027

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gterzian force-pushed the fix_closing_window branch from 0d4c16c to afed14c Compare Jun 22, 2020

highfive removed the S-tests-failed label Jun 22, 2020

gterzian force-pushed the fix_closing_window branch 6 times, most recently from ec4d848 to db761f3 Compare Jun 22, 2020

gterzian marked this pull request as draft Jun 23, 2020

gterzian force-pushed the fix_closing_window branch from db761f3 to 64640f9 Compare Jun 24, 2020

gterzian changed the title ~~Constellation: don't make shutdown depend on having exited all pipelines~~ Use BHM to terminate hanging JS threads when closing window Jun 24, 2020

gterzian force-pushed the fix_closing_window branch 5 times, most recently from c8eaf18 to f083da4 Compare Jun 30, 2020

highfive unassigned paulrouget Jun 30, 2020

highfive added S-awaiting-merge and removed S-awaiting-review S-needs-squash labels Jun 30, 2020

highfive added S-tests-failed and removed S-awaiting-merge labels Jun 30, 2020

ensure clean shutdown of all threads running JS

44ebca7

gterzian force-pushed the fix_closing_window branch from f083da4 to 44ebca7 Compare Jun 30, 2020

highfive added S-awaiting-review and removed S-tests-failed labels Jun 30, 2020

highfive added S-awaiting-merge and removed S-awaiting-review labels Jun 30, 2020

bors-servo merged commit b9404fc into servo:master Jun 30, 2020
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highfive removed the S-awaiting-merge label Jun 30, 2020

gterzian deleted the fix_closing_window branch Jun 30, 2020

Ensure clean shutdown of JS threads #27016

Ensure clean shutdown of JS threads #27016

gterzian commented Jun 22, 2020 •

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Ensure clean shutdown of JS threads #27016

Ensure clean shutdown of JS threads #27016

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