Assertion failure self.get_pending_parsing_blocking_script().is_none() || script.is_none()

[cbrewster]

Run: ./mach run -d http://www.robinwieruch.de/the-soundcloud-client-in-react-redux/

ERROR:constellation::constellation: Panic: assertion failed: self.get_pending_parsing_blocking_script().is_none() || script.is_none()
ERROR:constellation::constellation: Backtrace:
frame #0  - 0x0000000110a17120 - backtrace::backtrace::trace::hccde8df28b4db2a2
frame #1  - 0x0000000110a16fca - backtrace::capture::Backtrace::new::h42f95930bb8c5ee8
frame #2  - 0x000000010f844075 - util::thread::spawn_named_with_send_on_panic::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::hcdef76f7bd2e69e9
frame #3  - 0x000000010f844670 - extern $u22$rust.call$u22$$u20$fn$LP$$u5b$closure$SP$DefId$u20$$u7b$$u20$krate.$u20$47$C$$u20$node.$u20$DefIndex$LP$2393$RP$$u20$$u7d$$u20$0.ipc_channel..ipc..IpcSender$LT$$LP$core..option..Option$LT$msg..constellation_msg..PipelineId$GT$$C$$u20$std..string..String$C$$u20$std..string..String$RP$$GT$$C$$u20$1.core..option..Option$LT$msg..constellation_msg..PipelineId$GT$$u5d$$C$$u20$$LP$$RF$core..any..Any$C$$RP$$RP$::once_shim.191684::hc9bbdd66b2ae9c80
frame #4  - 0x000000010f84461c - _<F as alloc..boxed..FnBox<A>>::call_box::hdbcdd643ee67aa9c
frame #5  - 0x00000001109c03cf - util::panicking::initiate_panic_hook::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::hddf831bcfa835e79
frame #6  - 0x00000001109bffd3 - _<std..thread..local..LocalKey<T>>::with::h49e68c592f601e39
frame #7  - 0x00000001109bfe26 - util::panicking::initiate_panic_hook::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h0fcde37d4d058867
frame #8  - 0x0000000110d00d64 - std::panicking::rust_panic_with_hook::h983af77c1a2e581b
frame #9  - 0x000000010ebdb2e7 - std::panicking::begin_panic::h0bf39f6d43ab9349
frame #10 - 0x000000010f452d54 - script::dom::document::Document::set_pending_parsing_blocking_script::h72ebe74ae81b081f
frame #11 - 0x000000010f5f53c8 - script::dom::htmlscriptelement::HTMLScriptElement::prepare::h944c8c8a0ea41891
frame #12 - 0x000000010f6c42f7 - script::parse::html::_<impl html5ever..tree_builder..interface..TreeSink for script..dom..servohtmlparser..Sink>::complete_script::hffc11d06fff5906f
frame #13 - 0x000000010f6a88e0 - _<html5ever..tree_builder..TreeBuilder<Handle, Sink> as html5ever..tree_builder..rules..TreeBuilderStep>::step::hca68e2bc2432aa52
frame #14 - 0x000000010f68e924 - _<html5ever..tree_builder..TreeBuilder<Handle, Sink>>::process_to_completion::h2faf0c83b88df088
frame #15 - 0x000000010f68a2cc - _<html5ever..tree_builder..TreeBuilder<Handle, Sink> as html5ever..tokenizer..interface..TokenSink>::process_token::he45af09b32dfea6d
frame #16 - 0x000000010f68949d - _<html5ever..tokenizer..Tokenizer<Sink>>::process_token::hf3778c2010ac92bf
frame #17 - 0x000000010f6d7aa9 - _<html5ever..tokenizer..Tokenizer<Sink>>::emit_current_tag::h7e260b3f099be738
frame #18 - 0x000000010f6cef0a - _<html5ever..tokenizer..Tokenizer<Sink>>::step::hc800f3fb49ad6b84
frame #19 - 0x000000010f6cb0f3 - _<html5ever..tokenizer..Tokenizer<Sink>>::run::ha80cf9bcfaf349a8
frame #20 - 0x000000010f6ebdf4 - script::dom::servohtmlparser::ServoHTMLParser::do_parse_sync::h7868138b6419f7a1
frame #21 - 0x000000010f6ebb97 - script::dom::servohtmlparser::ServoHTMLParser::parse_sync::_$u7b$$u7b$closure$u7d$$u7d$::h0ebcb12addb25692
frame #22 - 0x000000010f6eba7f - profile_traits::time::profile::h1a1eac59628cb425
frame #23 - 0x000000010f6847f6 - script::dom::servohtmlparser::ServoHTMLParser::parse_sync::ha88022f6608066ce
frame #24 - 0x000000010f6ec5fa - script::dom::servohtmlparser::ServoHTMLParser::resume::h5537b3f413e82f15
frame #25 - 0x000000010f457604 - script::parse::ParserRef::resume::he80e04c197ee93fd
frame #26 - 0x000000010ec81690 - script::dom::document::Document::finish_load::h13371ea3d4ab55e4
frame #27 - 0x000000010f5f233c - _<script..dom..htmlscriptelement..ScriptContext as net_traits..AsyncResponseListener>::response_complete::h8b6124ed78c481e9
frame #28 - 0x0000000110287215 - net_traits::ResponseAction::process::hedeb8786331fefcc
frame #29 - 0x000000010f5f9066 - _<script..network_listener..ListenerRunnable<T> as script..script_thread..Runnable>::handler::ha5a5c643cf11f4e8
frame #30 - 0x000000010f85b00c - script::script_thread::ScriptThread::handle_msg_from_script::h6a6b4ae37d32650d
frame #31 - 0x000000010f8e9118 - script::script_thread::ScriptThread::handle_msgs::_$u7b$$u7b$closure$u7d$$u7d$::hdfba591677ee0854
frame #32 - 0x000000010f8e8c85 - script::script_thread::ScriptThread::profile_event::h180ff2036b8c2783
frame #33 - 0x000000010f8b90db - script::script_thread::ScriptThread::handle_msgs::h45a47f1f1786f911
frame #34 - 0x000000010f8585fc - script::script_thread::ScriptThread::start::hf0f02e16b9da3912
frame #35 - 0x000000010f8585ab - _<script..script_thread..ScriptThread as script_traits..ScriptThreadFactory>::create::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::hb106c460c5297919
frame #36 - 0x000000010f858301 - profile_traits::mem::ProfilerChan::run_with_memory_reporting::h90164fdc02bc9ddf
frame #37 - 0x000000010f844d96 - _<script..script_thread..ScriptThread as script_traits..ScriptThreadFactory>::create::_$u7b$$u7b$closure$u7d$$u7d$::h3f833182b51a6573
frame #38 - 0x000000010f84342e - util::thread::spawn_named_with_send_on_panic::_$u7b$$u7b$closure$u7d$$u7d$::h8444e95fb5b3a49b
frame #39 - 0x000000010f8431e7 - _<std..panic..AssertUnwindSafe<F> as core..ops..FnOnce<()>>::call_once::hcfab80e1e643709e
frame #40 - 0x000000010f84313b - std::panicking::try::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h5096e88519db480e
frame #41 - 0x000000010f8439f4 - std::panicking::try::call::h050129f436c26836
frame #42 - 0x0000000110d1ca2b - __rust_try
frame #43 - 0x0000000110d1c9c5 - __rust_maybe_catch_panic
frame #44 - 0x000000010f84308d - std::panicking::try::_$u7b$$u7b$closure$u7d$$u7d$::hbe4ce1d0ed5283dc
frame #45 - 0x000000010f842fdf - _<std..thread..local..LocalKey<T>>::with::he2ddd4f1ae360bd1
frame #46 - 0x000000010f842e0f - std::panicking::try::h658821b100ed0f40
frame #47 - 0x000000010f842cee - std::panic::catch_unwind::hca6edbb3b9e41acb
frame #48 - 0x000000010f842b4c - std::thread::Builder::spawn::_$u7b$$u7b$closure$u7d$$u7d$::h2033c44455cf8048
frame #49 - 0x000000010f843bf7 - _<F as alloc..boxed..FnBox<A>>::call_box::h3d739ebefef9fe99
frame #50 - 0x0000000110d184a8 - std::sys::thread::Thread::new::thread_start::h9c883b6d445ece46
frame #51 - 0x00007fff9486599c - _pthread_body
frame #52 - 0x00007fff94865919 - _pthread_start

ERROR:constellation::constellation: Panic: called `Result::unwrap()` on an `Err` value: Error { repr: Custom(Custom { kind: Other, error: StringError("MPSC send failed") }) }
ERROR:constellation::constellation: Backtrace skipped (run with -Z full-backtraces to see every backtrace).
ERROR:constellation::constellation: Panic: called `Result::unwrap()` on an `Err` value: Error { repr: Custom(Custom { kind: Other, error: StringError("MPSC send failed") }) }
ERROR:constellation::constellation: Backtrace skipped (run with -Z full-backtraces to see every backtrace).
ERROR:constellation::constellation: Panic: called `Result::unwrap()` on an `Err` value: Error { repr: Custom(Custom { kind: Other, error: StringError("MPSC send failed") }) }
ERROR:constellation::constellation: Backtrace skipped (run with -Z full-backtraces to see every backtrace).
ERROR:constellation::constellation: Panic: called `Result::unwrap()` on an `Err` value: "SendError(..)"
ERROR:constellation::constellation: Backtrace skipped (run with -Z full-backtraces to see every backtrace).

[Ms2ger]

I suspect this is a symptom of servo/html5ever#198

[jdm]

The assertion is being triggered because we have a script element network load being completed, which invokes the parser, which encounters another script tag. Presumably the pending parsing blocking script hasn't been reset before we begin parsing.

[jdm]

Alternatively, perhaps the pending parser blocking script is a different one than the script that's being executed. I really want better documentation for what parts of the spec Document::finish_load is attempting to implement.

[cbrewster]

I can no longer reproduce this.