Re: [v8-users] Debugging mksnapshot bus error

['Ryan Manuel' via v8-users]

That did resolve the issue, but I'm not 100% positive it's a heap size 
issue. I was able to whittle my snapshot file down to a much smaller subset 
(55.1 MB down to 83 KB for the input file) and it still causes the same 
problem. The updated file is in this gist 
. 
Is there a way I could validate that it is the heap size problem vs. 
something else? I’m going to keep trying to see if I can figure out a 
smaller reproduction.

On Saturday, August 10, 2024 at 5:54:39 AM UTC-5 Ben Noordhuis wrote:

> Maybe check if a v8_enable_pointer_compression=false build works okay?
> It only happens with large snapshots, right? Comrpessed pointers don't
> work for heap sizes > 4 GB.
>
> On Tue, Aug 6, 2024 at 6:45 AM 'Ryan Manuel' via v8-users
>  wrote:
> >
> > Ah thanks for the advice. I put the output below of running the command 
> below. Any thoughts on what to do next?
> >
> > #
> > # Fatal error in ../../src/common/ptr-compr-inl.h, line 81
> > # Debug check failed: (tagged & kPtrComprCageBaseMask) == base() || 
> ((static_cast(tagged) & ::i::kSmiTagMask) == ::i::kSmiTag).
> > #
> > #
> > #
> > #FailureMessage Object: 0x16fc594b8
> >
> >  C stack trace ===
> >
> > 0 libv8_libbase.dylib 0x0001152776ec 
> v8::base::debug::StackTrace::StackTrace() + 32
> > 1 libv8_libbase.dylib 0x000115277728 
> v8::base::debug::StackTrace::StackTrace() + 28
> > 2 libv8_libplatform.dylib 0x000115495fe4 v8::platform::(anonymous 
> namespace)::PrintStackTrace() + 60
> > 3 libv8_libbase.dylib 0x00011524327c V8_Fatal(char const*, int, char 
> const*, ...) + 352
> > 4 libv8_libbase.dylib 0x000115242c2c v8::base::SetFatalFunction(void 
> (*)(char const*, int, char const*)) + 0
> > 5 libv8_libbase.dylib 0x000115243388 V8_Dcheck(char const*, int, 
> char const*) + 108
> > 6 mksnapshot 0x0001001bd720 
> v8::internal::V8HeapCompressionSchemeImpl::CompressObject(unsigned
>  
> long) + 124
> > 7 mksnapshot 0x0001005688c4 
> v8::internal::TaggedField, 0, 
> v8::internal::V8HeapCompressionSchemeImpl>::full_to_tagged(unsigned
>  
> long) + 24
> > 8 mksnapshot 0x0001005686a8 
> v8::internal::TaggedField, 0, 
> v8::internal::V8HeapCompressionSchemeImpl>::Relaxed_Store(v8::internal::Tagged,
>  
> int, v8::internal::Tagged>) + 
> 216
> > 9 mksnapshot 0x0001005684c8 
> v8::internal::TorqueGeneratedFeedbackVector v8::internal::HeapObject>::set_raw_feedback_slots(int, 
> v8::internal::Tagged v8::internal::MaybeWeak, v8::internal::Smi>>, 
> v8::internal::WriteBarrierMode) + 648
> > 10 mksnapshot 0x000100567184 
> v8::internal::FeedbackVector::Set(v8::internal::FeedbackSlot, 
> v8::internal::Tagged>, 
> v8::internal::WriteBarrierMode) + 180
> > 11 mksnapshot 0x0001012f702c 
> v8::internal::NexusConfig::SetFeedbackPair(v8::internal::Tagged,
>  
> v8::internal::FeedbackSlot, 
> v8::internal::Tagged>, 
> v8::internal::WriteBarrierMode, 
> v8::internal::Tagged>, 
> v8::internal::WriteBarrierMode) const + 484
> > 12 mksnapshot 0x0001012fa8ac void 
> v8::internal::FeedbackNexus::SetFeedback,
>  
> v8::internal::MaybeWeak>(v8::internal::Tagged>,
>  
> v8::internal::WriteBarrierMode, 
> v8::internal::Tagged>, 
> v8::internal::WriteBarrierMode) + 160
> > 13 mksnapshot 0x0001012fb470 
> v8::internal::FeedbackNexus::ConfigureMonomorphic(v8::internal::Handle,
>  
> v8::internal::Handle, v8::internal::MaybeObjectHandle 
> const&) + 324
> > 14 mksnapshot 0x000100f28e1c 
> v8::internal::IC::ConfigureVectorState(v8::internal::Handle,
>  
> v8::internal::Handle, v8::internal::MaybeObjectHandle 
> const&) + 160
> > 15 mksnapshot 0x000100f28d50 
> v8::internal::IC::ConfigureVectorState(v8::internal::Handle,
>  
> v8::internal::Handle, 
> v8::internal::Handle) + 112
> > 16 mksnapshot 0x000100f38f04 
> v8::internal::KeyedStoreIC::UpdateStoreElement(v8::internal::Handle,
>  
> v8::internal::KeyedAccessStoreMode, 
> v8::internal::Handle) + 416
> > 17 mksnapshot 0x000100f3c49c 
> v8::internal::StoreInArrayLiteralIC::Store(v8::internal::Handle,
>  
> v8::internal::Handle, 
> v8::internal::Handle) + 1176
> > 18 mksnapshot 0x000100f44c24 
> v8::internal::__RT_impl_Runtime_StoreInArrayLiteralIC_Miss(v8::internal::Arguments<(v8::internal::ArgumentsType)0>,
>  
> v8::internal::Isolate*) + 1012
> > 19 mksnapshot 0x000100f445dc 
> v8::internal::Runtime_StoreInArrayLiteralIC_Miss(int, unsigned long*, 
> v8::internal::Isolate*) + 288
> > 20 ??? 0x391473cfc750 0x0 + 62760005125968
> > 21 ??? 0x000170e98ec0 0x0 + 6189321920 <(618)%20932-1920>
> > 22 ??? 0x391473a7031c 0x0 + 62760002454300
> > 23 ??? 0x391473a7031c 0x0 + 62760002454300
> > 24 ??? 0x391473a7031c 0x0 + 62760002454300
> > 25 ??? 0x391473a7031c 0x0 + 62760002454300
> > 26 ??? 0x391473a7031c 0x0 + 62760002454300
> > 27 ??? 0x391473a6a098 0x0 + 62760002429080
> > 28 ??? 0x391473a69cd4 0x0 + 62760002428116
> > 29 mksn

Re: [v8-users] Debugging mksnapshot bus error

['Ryan Manuel' via v8-users]

I was able to simplify the code even more and still recreate the error. 
I've pasted it below.

The weird thing is if I change this line:

applyDefs.definitions[modulePath].apply(mod.exports, [mod, applyDefs])

to

applyDefs.definitions[modulePath].call(mod.exports, mod, applyDefs)

Everything works properly.

let defs = {}

defs['nat-mods.json'] = function (mod, applyDefinition) {
mod.exports = {}
}

defs['plugins.json'] = function (mod, applyDefinition) {
mod.exports = {}
}

defs['nat-mods.js'] = function (mod, applyDefinition) {
mod.exports = applyDefinition('nat-mods.json')
}

defs['plugins.js'] = function (mod, applyDefinition) {
mod.exports = applyDefinition('plugins.json')
}

defs['index.js'] = function (mod, applyDefinition) {
mod.exports = function gensync () {}
}

defs['async'] = function (mod, applyDefinition) {
function gensync () {
return applyDefinition('index.js')
}
gensync()()
}

defs['utils'] = function (mod, applyDefinition) {
}

defs['caching.js'] = function (mod, applyDefinition) {
applyDefinition('async')
applyDefinition('utils')
}

defs['import.cjs'] = function (mod, applyDefinition) {
}

defs['firstPath'] = function (mod, applyDefinition) {
applyDefinition('plugins.json')
applyDefinition('nat-mods.js')
applyDefinition('plugins.js')
applyDefinition('caching.js')
applyDefinition('import.cjs')
}

applyDefs.definitions = defs
applyDefs.exports = {}

function applyDefs (modulePath) {
const mod = {
exports: {},
children: [],
loaded: true,
parent: {},
paths: [],
require: applyDefs,
filename: modulePath,
id: modulePath,
path: modulePath,
}

applyDefs.exports[modulePath] = mod
applyDefs.definitions[modulePath].apply(mod.exports, [mod, applyDefs])

return mod.exports
}

applyDefs('firstPath')


On Tuesday, August 13, 2024 at 10:27:18 AM UTC-5 Ryan Manuel wrote:

> That did resolve the issue, but I'm not 100% positive it's a heap size 
> issue. I was able to whittle my snapshot file down to a much smaller subset 
> (55.1 MB down to 83 KB for the input file) and it still causes the same 
> problem. The updated file is in this gist 
> . 
> Is there a way I could validate that it is the heap size problem vs. 
> something else? I’m going to keep trying to see if I can figure out a 
> smaller reproduction.
>
> On Saturday, August 10, 2024 at 5:54:39 AM UTC-5 Ben Noordhuis wrote:
>
>> Maybe check if a v8_enable_pointer_compression=false build works okay? 
>> It only happens with large snapshots, right? Comrpessed pointers don't 
>> work for heap sizes > 4 GB. 
>>
>> On Tue, Aug 6, 2024 at 6:45 AM 'Ryan Manuel' via v8-users 
>>  wrote: 
>> > 
>> > Ah thanks for the advice. I put the output below of running the command 
>> below. Any thoughts on what to do next? 
>> > 
>> > # 
>> > # Fatal error in ../../src/common/ptr-compr-inl.h, line 81 
>> > # Debug check failed: (tagged & kPtrComprCageBaseMask) == base() || 
>> ((static_cast(tagged) & ::i::kSmiTagMask) == ::i::kSmiTag). 
>> > # 
>> > # 
>> > # 
>> > #FailureMessage Object: 0x16fc594b8 
>> > 
>> >  C stack trace === 
>> > 
>> > 0 libv8_libbase.dylib 0x0001152776ec 
>> v8::base::debug::StackTrace::StackTrace() + 32 
>> > 1 libv8_libbase.dylib 0x000115277728 
>> v8::base::debug::StackTrace::StackTrace() + 28 
>> > 2 libv8_libplatform.dylib 0x000115495fe4 v8::platform::(anonymous 
>> namespace)::PrintStackTrace() + 60 
>> > 3 libv8_libbase.dylib 0x00011524327c V8_Fatal(char const*, int, 
>> char const*, ...) + 352 
>> > 4 libv8_libbase.dylib 0x000115242c2c 
>> v8::base::SetFatalFunction(void (*)(char const*, int, char const*)) + 0 
>> > 5 libv8_libbase.dylib 0x000115243388 V8_Dcheck(char const*, int, 
>> char const*) + 108 
>> > 6 mksnapshot 0x0001001bd720 
>> v8::internal::V8HeapCompressionSchemeImpl::CompressObject(unsigned
>>  
>> long) + 124 
>> > 7 mksnapshot 0x0001005688c4 
>> v8::internal::TaggedField, 0, 
>> v8::internal::V8HeapCompressionSchemeImpl>::full_to_tagged(unsigned
>>  
>> long) + 24 
>> > 8 mksnapshot 0x0001005686a8 
>> v8::internal::TaggedField, 0, 
>> v8::internal::V8HeapCompressionSchemeImpl>::Relaxed_Store(v8::internal::Tagged,
>>  
>> int, v8::internal::Tagged>) + 
>> 216 
>> > 9 mksnapshot 0x0001005684c8 
>> v8::internal::TorqueGeneratedFeedbackVector> v8::internal::HeapObject>::set_raw_feedback_slots(int, 
>> v8::internal::Tagged> v8::internal::MaybeWeak, v8::internal::Smi>>, 
>> v8::internal::WriteBarrierMode) + 648 
>> > 10 mksnapshot 0x000100567184 
>> v8::internal::FeedbackVector::Set(v8::internal::FeedbackSlot, 
>> v8::internal::Tagged>, 
>> v8::internal::WriteBarrierMode) + 180 
>> > 11 mksnapshot 0x0001012f702c 
>> v8::internal::NexusConfig::SetFeedbackPair(v8::internal::Tagged,
>>  
>> v8::internal::FeedbackSlot, 
>> v8::internal::Tagged>, 
>> v8::internal::WriteBarrierMode, 
>> v8::internal::Tagged>, 
>> v8::internal::WriteBarrierMode) const + 484 
>> > 12 mksnapshot