WebGLThread panic while loading https://aframe.io/examples on Android

[ferjm]

https://aframe.io/examples is unresponsive and never ends loading.

10-21 19:42:26.577 23447 23463 I simpleservo: load_uri: https://aframe.io/
10-21 19:42:26.579 23447 23486 I simpleservo: ResourceReader::read(rippy.png)
10-21 19:42:26.586  1650  1650 I PhenotypeExpConfig: com.google.android.apps.inputmethod.libs.experiments.PhenotypeExperimentConfiguration: refreshConfiguration() : Force = false : UpdateAvailable = false : Age = 51 minutes : MaxAge = 720 minutes
10-21 19:42:26.586  1650  1650 I LatinIme: com.google.android.apps.inputmethod.libs.latin5.LatinIme: onDeactivate()
10-21 19:42:27.144  2267 17049 I Icing   : Indexing com.google.android.gm-internal.3p:EmailMessage from com.google.android.gm
10-21 19:42:27.182  2267 17049 I Icing   : Indexing done com.google.android.gm-internal.3p:EmailMessage
10-21 19:42:27.686 23447 23490 D skia    : Device does NOT support ARM NEON instructions!
10-21 19:42:27.788 23447 23530 E simpleservo: Error at https://aframe.io/js/common.js:2:162 $ is not defined
10-21 19:42:28.243 23447 23466 D simpleservo: No DPDB device match.
10-21 19:42:28.243 23447 23466 D simpleservo: Failed to recalculate device parameters.
10-21 19:42:28.244 23447 23466 D simpleservo: Using fallback Android device measurements.
10-21 19:42:28.321  2267 17049 I Icing   : Indexing com.google.android.gm-internal.3p:EmailMessage from com.google.android.gm
10-21 19:42:28.367 23447 23466 D simpleservo: A-Frame Version: 0.8.2 (Date 2018-04-15, Commit #b20527f)
10-21 19:42:28.367 23447 23466 D simpleservo: three Version:
10-21 19:42:28.367 23447 23466 D simpleservo: github:supermedium/three.js#r90fixMTLLoader
10-21 19:42:28.367 23447 23466 D simpleservo: WebVR Polyfill Version:
10-21 19:42:28.367 23447 23466 D simpleservo: ^0.10.5
10-21 19:42:28.368 23447 23685 W GStreamer+GST_ELEMENT_FACTORY: 0:00:16.845648970 0xc19bd060 gstelementfactory.c:456:gst_element_factory_make no such element factory "scaletempo"!
10-21 19:42:28.368 23447 23685 W GLib    : GstPlayer: scaletempo element not available. Audio pitch will not be preserved during trick modes
10-21 19:42:28.377 23447 23466 D simpleservo: THREE.WebGLRenderer
10-21 19:42:28.377 23447 23466 D simpleservo: 90
10-21 19:42:28.385 23447 23485 E simpleservo: Last GL operation failed: GetExtensions(WebGLSender(..))
10-21 19:42:28.385 23447 23466 D simpleservo: thread 'WebGLThread' panicked at 'assertion failed: `(left == right)`
10-21 19:42:28.385 23447 23466 D simpleservo:   left: `1280`,
10-21 19:42:28.385 23447 23466 D simpleservo:  right: `0`: Unexpected WebGL error: 0x500 (1280)', components/canvas/webgl_thread.rs:1231:9
10-21 19:42:28.385 23447 23466 D simpleservo: note: Run with `RUST_BACKTRACE=1` for a backtrace.
10-21 19:42:28.385 23447 23466 D simpleservo: THREE.WebGLRenderer: WEBGL_depth_texture extension not supported.
10-21 19:42:28.385 23447 23466 D simpleservo: THREE.WebGLRenderer: ANGLE_instanced_arrays extension not supported.

[nox]

AFAIK recent OpenGL versions don't like glGetString(GL_EXTENSIONS), the GetExtensions stuff should probably be reimplemented with glGetStringi.

[jdm]

This was probably fixed by #24055.

[asajeffrey]

I'm seeing this on MacOS on https://www.joshmatthews.net/demos/lamp.html

assertion failed: `(left == right)`
  left: `1280`,
 right: `0`: Unexpected WebGL error: 0x500 (1280) (thread WebGL thread, at components/canvas/webgl_thread.rs:1566)
stack backtrace:
   0: __ZN9backtrace9backtrace5trace17hcc8b472f5f9a492fE (0x111d95b1b)
   1: __ZN9backtrace7capture9Backtrace3new17hc3f3beeabc50169eE (0x111d94d07)
   2: __ZN5servo4main28_$u7b$$u7b$closure$u7d$$u7d$17h167dc8a19a30045aE (0x10ef5fb7b)
   3: __ZN3std9panicking20rust_panic_with_hook17h099fe3773ce1a793E (0x111f21b91)
   4: __ZN3std9panicking18continue_panic_fmt17h8a4b76634870b383E (0x111f215fc)
   5: __ZN3std9panicking15begin_panic_fmt17hd8effa78bdafa918E (0x111f2155d)
   6: __ZN6canvas12webgl_thread9WebGLImpl5apply17h619eb08cf51898acE (0x1116231ca)
   7: __ZN6canvas12webgl_thread11WebGLThread10handle_msg17h3acb546d266489ccE.llvm.1569179447716100275 (0x111614899)
   8: __ZN6canvas12webgl_thread11WebGLThread7process17h6cd810e725961106E (0x111613237)
   9: __ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h113b23693ba0a429E (0x1115f672c)
  10: __ZN3std9panicking3try7do_call17ha798e4151ea04539E.llvm.791569682819744604 (0x11167c471)
  11: ___rust_maybe_catch_panic (0x111f29f2e)
  12: __ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17h5f00f8b678a57938E (0x111627ef4)
  13: __ZN83_$LT$alloc..boxed..Box$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once17hb03304ace7f89c63E (0x111f112bd)
  14: __ZN3std3sys4unix6thread6Thread3new12thread_start17hd2d570f25bb299f3E (0x111f2945d)
  15: __pthread_body (0x7fff6f7be2ea)
  16: __pthread_start (0x7fff6f7c1248)
[2019-09-03T14:53:34Z ERROR servo] assertion failed: `(left == right)`
  left: `1280`,
 right: `0`: Unexpected WebGL error: 0x500 (1280)
called `Result::unwrap()` on an `Err` value: () (thread ScriptThread PipelineId { namespace_id: PipelineNamespaceId(1), index: PipelineIndex(1) }, at src/libcore/result.rs:1084)
stack backtrace:
   0: __ZN9backtrace9backtrace5trace17hcc8b472f5f9a492fE (0x111d95b1b)
   1: __ZN9backtrace7capture9Backtrace3new17hc3f3beeabc50169eE (0x111d94d07)
   2: __ZN5servo4main28_$u7b$$u7b$closure$u7d$$u7d$17h167dc8a19a30045aE (0x10ef5fb7b)
   3: __ZN3std9panicking20rust_panic_with_hook17h099fe3773ce1a793E (0x111f21b91)
   4: __ZN3std9panicking18continue_panic_fmt17h8a4b76634870b383E (0x111f215fc)
   5: _rust_begin_unwind (0x111f214f8)
   6: __ZN4core9panicking9panic_fmt17h885799c19d2b8b0cE (0x111f41d2e)
   7: __ZN4core6result13unwrap_failed17h91161a3faccc6622E (0x111f41e08)
   8: __ZN208_$LT$script..dom..webglrenderingcontext..WebGLRenderingContext$u20$as$u20$script..dom..bindings..codegen..Bindings..WebGLRenderingContextBinding..WebGLRenderingContextBinding..WebGLRenderingContextMethods$GT$24GetShaderPrecisionFormat17h9dccfe699a020935E (0x10fc30890)
   9: __ZN101_$LT$std..panic..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$$LP$$RP$$GT$$GT$9call_once17h3de929e841ce6153E (0x10f855b3c)
  10: __ZN3std9panicking3try7do_call17h9588b1ccfd1452c5E.llvm.2287604874008334462 (0x10f50d97b)
  11: ___rust_maybe_catch_panic (0x111f29f2e)
  12: __ZN6script3dom8bindings7codegen8Bindings28WebGLRenderingContextBinding28WebGLRenderingContextBinding24getShaderPrecisionFormat17h37dd0a133135a062E (0x10f6a1183)
  13: _CallJitMethodOp (0x1102c8bd1)
  14: __ZN6script3dom8bindings5utils12generic_call17hfdcb7365d5dc5d99E (0x10f593edc)
  15: __ZN6script3dom8bindings5utils14generic_method17h9f41701f09ee5500E (0x10f594031)
  16: __ZN2js23InternalCallOrConstructEP9JSContextRKN2JS8CallArgsENS_14MaybeConstructE (0x1102ef7a6)
  17: __ZL9InterpretP9JSContextRN2js8RunStateE (0x1102e91b8)
  18: __ZN2js9RunScriptEP9JSContextRNS_8RunStateE (0x1102dedef)
  19: __ZN2js13ExecuteKernelEP9JSContextN2JS6HandleIP8JSScriptEER8JSObjectRKNS2_5ValueENS_16AbstractFramePtrEPS9_ (0x1102f0a7f)
  20: __ZN2js7ExecuteEP9JSContextN2JS6HandleIP8JSScriptEER8JSObjectPNS2_5ValueE (0x1102f0c0b)
  21: __ZL8EvaluateP9JSContextN2js9ScopeKindEN2JS6HandleIP8JSObjectEERKNS3_22ReadOnlyCompileOptionsERNS3_10SourceTextIDsEENS3_13MutableHandleINS3_5ValueEEE (0x110381ae1)
  22: __ZN2JS12EvaluateUtf8EP9JSContextRKNS_22ReadOnlyCompileOptionsEPKcmNS_13MutableHandleINS_5ValueEEE (0x11038164c)
  23: __ZN14profile_traits4time7profile17h86274ea813c8e0bbE (0x10fd8d6cf)
  24: __ZN6script3dom11globalscope11GlobalScope37evaluate_script_on_global_with_result17h5fcf6d43658f07baE (0x10fbf496b)
  25: __ZN6script3dom17htmlscriptelement17HTMLScriptElement20run_a_classic_script17hfbaf59b8421f6f2bE (0x10fd36aeb)
  26: __ZN6script3dom17htmlscriptelement17HTMLScriptElement7execute17h7b5bb50423ae0273E (0x10fd35aec)
  27: __ZN6script3dom17htmlscriptelement17HTMLScriptElement7prepare17h2c4af22127db9358E (0x10fd33dbb)
  28: __ZN6script3dom11servoparser11ServoParser13do_parse_sync17h10ff4c06ba4f6d6eE (0x10fc1022e)
  29: __ZN14profile_traits4time7profile17h06648f974c4c3ad3E (0x10fd8aadd)
  30: __ZN6script3dom11servoparser11ServoParser10parse_sync17hb7e9cf1ce43cb1c2E.llvm.9861599294906097670 (0x10fc0fdae)
  31: __ZN6script3dom11servoparser11ServoParser43resume_with_pending_parsing_blocking_script17h9b4e17f141a036b8E (0x10fc0e947)
  32: __ZN6script3dom8document8Document39process_pending_parsing_blocking_script17h5ce047c99b6c4f1dE (0x10fbdaeed)
  33: __ZN6script3dom8document8Document38pending_parsing_blocking_script_loaded17h2a8c5a679950bda7E (0x10fbdaa9e)
  34: __ZN99_$LT$script..dom..htmlscriptelement..ScriptContext$u20$as$u20$net_traits..FetchResponseListener$GT$20process_response_eof17h13f89df3978a92c4E (0x10fd32865)
  35: __ZN76_$LT$net_traits..FetchResponseMsg$u20$as$u20$net_traits..Action$LT$T$GT$$GT$7process17hcb213968517b941eE (0x110056db7)
  36: __ZN101_$LT$script..network_listener..ListenerTask$LT$A$C$Listener$GT$$u20$as$u20$script..task..TaskOnce$GT$8run_once17hdebdb50fe0e907cfE (0x10fef445c)
  37: __ZN43_$LT$T$u20$as$u20$script..task..TaskBox$GT$7run_box17hd44859c1537fa138E (0x11007fa0e)
  38: __ZN6script13script_thread12ScriptThread22handle_msg_from_script17h74e2f7a20e7f0cffE (0x10fc5fd97)
  39: __ZN6script13script_thread12ScriptThread11handle_msgs17h54af4014b8fc8d3cE.llvm.9861599294906097670 (0x10fc5776b)
  40: __ZN14profile_traits3mem12ProfilerChan25run_with_memory_reporting17hefa8676c53b37e03E (0x10fd8a4f7)
  41: __ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h0f7d1a5666f3634eE (0x10f553dfc)
  42: __ZN3std9panicking3try7do_call17hacfa6be0a736e414E.llvm.2287604874008334462 (0x10f515c8a)
  43: ___rust_maybe_catch_panic (0x111f29f2e)
  44: __ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17hbc2dc4e9c1ef9ad5E (0x10f741745)
  45: __ZN83_$LT$alloc..boxed..Box$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once17hb03304ace7f89c63E (0x111f112bd)
  46: __ZN3std3sys4unix6thread6Thread3new12thread_start17hd2d570f25bb299f3E (0x111f2945d)
  47: __pthread_body (0x7fff6f7be2ea)
  48: __pthread_start (0x7fff6f7c1248)
[2019-09-03T14:53:34Z ERROR servo] called `Result::unwrap()` on an `Err` value: ()

[jdm]

@asajeffrey That's fixed by #24111.

[asajeffrey]

Er, is it? This panic is caused by GetExtensions erroring, which was addressed by #24055, but

servo/components/canvas/webgl_thread.rs

Line 1728 in 4f4e219

gl.get_integer_v(gl::NUM_EXTENSIONS, &mut ext_count);

produces error 0x500 for me.

[jdm]

Oh dear.

[jdm]

We may need to make the fix from #24055 conditional on whether it's a webgl 1 or webgl 2 context.

[asajeffrey]

The following fixes the panic, but isn't exactly lovely:

$ git diff
diff --git a/components/canvas/webgl_thread.rs b/components/canvas/webgl_thread.rs
index 7844c762cf..d0d8bf2021 100644
--- a/components/canvas/webgl_thread.rs
+++ b/components/canvas/webgl_thread.rs
@@ -1727,6 +1727,11 @@ impl WebGLImpl {
         unsafe {
             gl.get_integer_v(gl::NUM_EXTENSIONS, &mut ext_count);
         }
+        // Fall back to the depricated extensions API if that fails
+        if gl.get_error() != gl::NO_ERROR {
+            chan.send(gl.get_string(gl::EXTENSIONS)).unwrap();
+           return;
+        }
         let ext_count = ext_count[0] as usize;
         let mut extensions = Vec::with_capacity(ext_count);
         for idx in 0..ext_count {

[asajeffrey]

It would be nicer to use the GL version to determine which API to use, but who knows if that will work with all drivers?