[browser][MT] enable jiterp

[pavelsavara]

Testing ...

Fixes #100273

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[pavelsavara]

There is GC deadlock with Finalizer on this PR.
Is there something that jiterp could be trying to lock, that is already locked on another thread that is suspended ?
@kg

[kg]

There is GC deadlock with Finalizer on this PR. Is there something that jiterp could be trying to lock, that is already locked on another thread that is suspended ? @kg

It's possible jiterp's C helpers might be missing GC state transitions. We could do an audit of all of them.

[pavelsavara]

What's the design ?
I guess the generated code should be in GC unsafe mode.

But I don't know if the interp is running in

• GC unsafe
• GC safe
• or mixed

And if jiterp should share the same rules ?

[kg]

What's the design ? I guess the generated code should be in GC unsafe mode.

But I don't know if the interp is running in

* GC unsafe

* GC safe

* or mixed

And if jiterp should share the same rules ?

jiterp traces are called directly by the interp without a transition so they inherit whatever state it's in, it's possible some of the helpers jiterp calls out to (written in c) need transitions and are missing them. it's also possible they contain transitions and shouldn't. i never put any thought into it at the time.

i mentioned on discord also that we should probably disable jiterp on the finalizer thread. the way jiterp works right now, each thread needs to JIT its own copy of the trace it's trying to run, and there's little upside to doing that on the finalizer thread to run a finalizer. it's possible that the process of compiling traces could deadlock if it happens on the finalizer thread, i think.

[pavelsavara]

So, Chrome is not guilty for the GC deadlock issue we have on MT with jiterp.
It happens on Firefox too.

See Log

[pavelsavara]

Re-confirmed. Jiterp is causing GC deadlocks

This is firefox log

[11:54:22] info: [PASS] System.Collections.Concurrent.Tests.ConcurrentDictionary_Generic_Tests_enum_enum.ICollection_Generic_Remove_EveryValue
[11:54:27] info: [0x000fb4ac--UI- 11:54:27.555] MONO_WASM: Dumping web worker info as seen by UI thread, it could be stale:
[11:54:27] info: 000 | 0x000fb4ac--UI-: isRunning: true isAttached: true isEventLoop:false reuseCount:  0 - UI Thread
[11:54:27] info: 001 | 0x017da270-dpty: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 -
[11:54:27] info: 002 | 0x034c86b8--IO-: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 -
[11:54:27] info: 003 | 0x039d0970-norm: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - Finalizer
[11:54:27] info: 004 | 0x03ef7ee0-pool: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET TP Worker
[11:54:27] info: 005 | 0x0421a218-gate: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET TP Gate
[11:54:27] info: 007 | 0x05ad0030-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET Long Running Task
[11:54:27] info: 008 | 0x05cd02e0-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  2 - .NET Long Running Task
[11:54:27] info: 006 | 0x060f0040-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  2 - .NET Long Running Task
[11:54:27] info: 010 | 0x062f02f0-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET Long Running Task
[11:54:27] info: 009 | 0x06600040-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET Long Running Task
[11:54:27] info: 012 | 0x06910040-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET Long Running Task
[11:54:27] info: 011 | 0x06c20040-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET Long Running Task
[11:54:27] info: 014 | 0x06f30040-long: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET Long Running Task
[11:54:27] info: 013 | 0x075d8680-pool: isRunning: true isAttached: true isEventLoop:false reuseCount:  1 - .NET TP Worker
[11:54:27] info: 016 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  5 - unregistered:(.NET Long Running Task)
[11:54:27] info: 028 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  2 - unregistered:(.NET Long Running Task)
[11:54:27] info: 021 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  4 - unregistered:(.NET Long Running Task)
[11:54:27] info: 023 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  3 - unregistered:(.NET Long Running Task)
[11:54:27] info: 017 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  4 - unregistered:(.NET Long Running Task)
[11:54:27] info: 024 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  3 - unregistered:(.NET Long Running Task)
[11:54:27] info: 029 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  2 - unregistered:(.NET Long Running Task)
[11:54:27] info: 020 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  3 - unregistered:(.NET Long Running Task)
[11:54:27] info: 019 | --08780000-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  4 - unregistered:(.NET Long Running Task)
[11:54:27] info: 025 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  2 - unregistered:(.NET Long Running Task)
[11:54:27] info: 022 | --0acd0000-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  3 - unregistered:(.NET Long Running Task)
[11:54:27] info: 030 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  2 - unregistered:(.NET Long Running Task)
[11:54:27] info: 018 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  4 - unregistered:(.NET Long Running Task)
[11:54:27] info: 026 | --0a5b0000-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  3 - unregistered:(.NET Long Running Task)
[11:54:27] info: 015 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  5 - unregistered:(.NET Long Running Task)
[11:54:27] info: 027 | --07c09c28-emsc: isRunning:false isAttached:false isEventLoop:false reuseCount:  3 - unregistered:(.NET Long Running Task)
[11:54:27] info: STATE CUE CARD: (? means a positive number, usually 1 or 2, * means any number)
[11:54:27] info: 	0x0	- starting (GOOD, unless the thread is running managed code)
[11:54:27] info: 	0x1	- detached (GOOD, unless the thread is running managed code)
[11:54:27] info: 	0x2	- running (BAD, unless it's the gc thread)
[11:54:27] info: 	0x?03	- async suspended (GOOD)
[11:54:27] info: 	0x?04	- self suspended (GOOD)
[11:54:27] info: 	0x?05	- async suspend requested (BAD)
[11:54:27] info: 	0x6	- blocking (BAD, unless there's no suspend initiator)
[11:54:27] info: 	0x?07	- blocking async suspended (GOOD)
[11:54:27] info: 	0x?08	- blocking self suspended (GOOD)
[11:54:27] info: 	0x?09	- blocking suspend requested (GOOD in coop; BAD in hybrid)
[11:54:27] info: --thread 0x3431f10 id 0xfb4ac [0] state 109
[11:54:27] info: --thread 0x1cdb318 id 0x17da270 [0] state 109
[11:54:27] info: --thread 0x3441a08 id 0x34c86b8 [0] state 109
[11:54:27] info: --thread 0x3433038 id 0x39d0970 [0] state 6
[11:54:27] info: --thread 0x3edfbc8 id 0x3ef7ee0 [0] state 109
[11:54:27] info: --thread 0x3ede268 id 0x421a218 [0] state 108
[11:54:27] info: --thread 0x4d6ee28 id 0x5ad0030 [0] state 109
[11:54:27] info: --thread 0x5ed3ad8 id 0x5cd02e0 [0] state 109
[11:54:27] info: --thread 0x50e4010 id 0x60f0040 [0] state 105
[11:54:27] info: --thread 0x50e4150 id 0x62f02f0 [0] state 109
[11:54:27] info: --thread 0x5035400 id 0x6600040 [0] state 2  GC INITIATOR
[11:54:27] info: --thread 0x58c6bd0 id 0x6910040 [0] state 109
[11:54:27] info: --thread 0x5ed6068 id 0x6c20040 [0] state 108
[11:54:27] info: --thread 0x5087050 id 0x6f30040 [0] state 109
[11:54:27] info: --thread 0x783bda0 id 0x75d8680 [0] state 109
[11:54:27] info: WAITING for 1 threads, got 0 suspended
[11:54:27] fail: [0x06600040-long 11:54:27.613] [MONO] suspend_thread suspend took 5000 ms, which is more than the allowed 5000 ms

the thread 0x60f0040 is not playing along.

[kg]

I think what we need to do is inspect all the jiterp C helpers and figure out which ones need GC transitions.