Intermittent crash in /css21_dev/html4/border-bottom-width-003.htm

[Manishearth]

http://build.servo.org/builders/linux-rel-css/builds/21/steps/test/logs/stdio

Result::unwrap() in RenderApi::add_raw_font

Tests with unexpected results:
  ▶ CRASH [expected PASS] /css21_dev/html4/border-bottom-width-003.htm
  │ 
  │ VMware, Inc.
  │ Gallium 0.4 on softpipe
  │ 3.3 (Core Profile) Mesa 12.0.1
  │ called `Result::unwrap()` on an `Err` value: Error { repr: Os { code: 32, message: "Broken pipe" } } (thread FontCacheThread, at ../src/libcore/result.rs:799)
  │ stack backtrace:
  │    0:     0x7f1a4459999d - backtrace::backtrace::trace::h0e60ef08c7c34e9f
  │    1:     0x7f1a4459a022 - backtrace::capture::Backtrace::new::h8bf319c36d8f5d1b
  │    2:     0x7f1a440b5b9d - servo::main::_{{closure}}::hf8fbab42eb66bcc2
  │    3:     0x7f1a45b492d5 - std::panicking::rust_panic_with_hook::hb1322e5f2588b4db
  │    4:     0x7f1a45b491a2 - std::panicking::begin_panic::hfbeda5aad583dc32
  │    5:     0x7f1a45b490e0 - std::panicking::begin_panic_fmt::h4fe9fb9d5109c4bf
  │    6:     0x7f1a45b49061 - rust_begin_unwind
  │    7:     0x7f1a45b85aec - core::panicking::panic_fmt::h4395919ece15c671
  │    8:     0x7f1a44f73e6b - core::result::unwrap_failed::hfcd13129071c9c47
  │    9:     0x7f1a44f75636 - webrender_traits::api::RenderApi::add_raw_font::hae25df6595fd0960
  │   10:     0x7f1a446e92a8 - gfx::font_cache_thread::FontCache::get_font_template_info::hfafdb1d339c210e8
  │   11:     0x7f1a446e2afb - gfx::font_cache_thread::FontCache::run::hfa4ef953905ce131
  │   12:     0x7f1a446be548 - std::panicking::try::do_call::hc4c6d76c70a037cf
  │   13:     0x7f1a45b51c56 - __rust_maybe_catch_panic
  │   14:     0x7f1a446cc693 - _<F as alloc..boxed..FnBox<A>>::call_box::he14ae8a6f207a867
  │   15:     0x7f1a45b47910 - std::sys::thread::Thread::new::thread_start::h022e3887023c6290
  │   16:     0x7f1a41fbf183 - start_thread
  │   17:     0x7f1a41ad637c - clone
  │   18:                0x0 - <unknown>
  │ ERROR:servo: called `Result::unwrap()` on an `Err` value: Error { repr: Os { code: 32, message: "Broken pipe" } }
  │ failed to receive response to font request: IoError(Error { repr: Os { code: 104, message: "Connection reset by peer" } }) (thread LayoutWorker worker 1/12, at ../src/libcore/result.rs:799)
  │ stack backtrace:
  │    0:     0x7f1a4459999d - backtrace::backtrace::trace::h0e60ef08c7c34e9f
  │    1:     0x7f1a4459a022 - backtrace::capture::Backtrace::new::h8bf319c36d8f5d1b
  │    2:     0x7f1a440b5b9d - servo::main::_{{closure}}::hf8fbab42eb66bcc2
  │    3:     0x7f1a45b492d5 - std::panicking::rust_panic_with_hook::hb1322e5f2588b4db
  │    4:     0x7f1a45b491a2 - std::panicking::begin_panic::hfbeda5aad583dc32
  │    5:     0x7f1a45b490e0 - std::panicking::begin_panic_fmt::h4fe9fb9d5109c4bf
  │    6:     0x7f1a45b49061 - rust_begin_unwind
  │    7:     0x7f1a45b85aec - core::panicking::panic_fmt::h4395919ece15c671
  │    8:     0x7f1a446c7694 - core::result::unwrap_failed::h3191a47cbfbe2a26
  │    9:     0x7f1a446ea67d - gfx::font_cache_thread::FontCacheThread::last_resort_font_template::ha68706aea12473f0
  │   10:     0x7f1a446ebd84 - gfx::font_context::FontContext::layout_font_group_for_style::h12581b43c9e1d236
  │   11:     0x7f1a444eb75e - layout::text::TextRunScanner::scan_for_runs::h3b0316bf9753abe8
  │   12:     0x7f1a44444ae5 - _<layout..construct..FlowConstructor<'a, ConcreteThreadSafeLayoutNode>>::build_flow_for_block_starting_with_fragments::h734e467eadd65787
  │   13:     0x7f1a44442fdd - _<layout..construct..FlowConstructor<'a, ConcreteThreadSafeLayoutNode>>::build_flow_for_block_like::haeee0e6dd119134a
  │   14:     0x7f1a444423a1 - _<layout..construct..FlowConstructor<'a, ConcreteThreadSafeLayoutNode>>::build_flow_for_block::he157d007672b36e1
  │   15:     0x7f1a443d34f5 - _<layout..construct..FlowConstructor<'a, ConcreteThreadSafeLayoutNode> as layout..traversal..PostorderNodeMutTraversal<ConcreteThreadSafeLayoutNode>>::process::h8b133743fa0745f9
  │   16:     0x7f1a443c3c88 - _<layout..traversal..RecalcStyleAndConstructFlows<'lc> as style..traversal..DomTraversalContext<N>>::process_postorder::h1ca248022560f325
  │   17:     0x7f1a444261ba - style::parallel::top_down_dom::h5272f51dd904376e
  │   18:     0x7f1a4443f9a3 - _<std..panic..AssertUnwindSafe<F> as core..ops..FnOnce<()>>::call_once::ha10e45c35d4626ed
  │   19:     0x7f1a443e8ff0 - std::panicking::try::do_call::h252c9570ed34727f
  │   20:     0x7f1a45b51c56 - __rust_maybe_catch_panic
  │   21:     0x7f1a4441035c - _<F as alloc..boxed..FnBox<A>>::call_box::h55e65dc38ba6cdd9
  │   22:     0x7f1a45b47910 - std::sys::thread::Thread::new::thread_start::h022e3887023c6290
  │   23:     0x7f1a41fbf183 - start_thread
  │   24:     0x7f1a41ad637c - clone
  │   25:                0x0 - <unknown>
  │ ERROR:servo: failed to receive response to font request: IoError(Error { repr: Os { code: 104, message: "Connection reset by peer" } })
  └ Pipeline failed in hard-fail mode.  Crashing!

[Manishearth]

cc @glennw

[hiikezoe]

Happened on /referrer-policy/origin-when-cross-origin/http-rp/same-origin/http-https/iframe-tag/same-origin-downgrade.no-redirect.http.html. #20102

[jdm]

This is #13730.