Upgrading v8 from 7.4 to 8.5

[Vinayaka Kamath]

Hello All,

I am involved with a project that relies on v8 for most of its features. We are trying to upgrade the v8 engine to 8.5 and the project compiles without any error.

We also have a debugger that uses inspector protocol -- however after the upgradation the debugger crashes when session_->dispatchProtocolMessage(message); is invoked.

I am relatively new to v8 and don't understand it completely, however I noticed that the implementation of platform, return values of Set, Get were changed between the versions(and the corresponding changes are made). I don't see any changes with respect to the inspector -- I am afraid I am missing something here. 

You can find our project here: https://github.com/couchbase/eventing/tree/master/third_party/inspector

Any help would be very much appreciated! 

The debugger crashes with the following message:

==============================================
# Fatal error in HandleScope::HandleScope
# Entering the V8 API without proper locking in place
#
== Minidump location: crash/cfecbc18-15f2-428d-a10256ac-40061e00.dmp Status: 1 ==
Failed to read from stderr pipe, err: EOF
Failed to read from stdout pipe, err: EOF
Exiting c++ debug worker with error: signal: illegal instruction
===============================================

Also the symbols in the coredump (after conversion from minidump to coredump) is not getting resolved. I see ????? for line numbers and function names!

[Vinayaka Kamath]

I have attached the stack trace from attaching the debugger to the running program below:

https://drive.google.com/drive/folders/124iiIB682-vgbN5S0BPG2mR2DmUe32lc?usp=sharing

[Ben Ernst]

Vinayaka, the answer is here in your console output.

# Fatal error in HandleScope::HandleScope
# Entering the V8 API without proper locking in place
#  

You want to use v8::Locker consistently, pretty much wherever you have a HandleScope you need to instantiate a v8::Locker immediately before.

Regards,

Ben

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[Vinayaka Kamath]

Hello Ben,

But I don't have an HandleScopes in my code -- neither in my InspectorClient nor in my agent. The error seems to be getting raised from v8::Utils::ApiCheck(). Do I need to set some flags in any of the changed function prototypes in the new v8 version? or does any of the new functions corresponding to the v8-inspector require a locker on isolate? Because the exact same code doesn't crash with older versions of v8.

Thanks 

[Vinayaka Kamath]

Hello,

While upgrading the v8 version -- I have replaced platform->CallOnForegroundThread  with platform->CallOnWorkerThread. Could the "Fatal error in HandleScope::HandleScope # Entering the V8 API without proper locking in place" happen because of that?

Thanks

[Ben Noordhuis]

On Tue, Nov 3, 2020 at 9:56 AM Vinayaka Kamath
<vinayak...@couchbase.com> wrote:
> While upgrading the v8 version -- I have replaced platform->CallOnForegroundThread with platform->CallOnWorkerThread. Could the "Fatal error in HandleScope::HandleScope # Entering the V8 API without proper locking in place" happen because of that?

The task calls into V8? Then yes, that's almost certainly it.