fiber stack issues with crystal 13

[phil294]

$ bin/ahk_x11.dev <<<'a = 1
$ b := a
$ echo %b%'
[debug] 0: a = 1
[debug] 1: b := a
[debug] 2: echo %b%
[debug] 3: 
[debug] x11: root_win = 1500
[debug] x11: _NET_ACTIVE_WINDOW = 346
[debug] x11: active window detection: 77594635
Failed to raise an exception: END_OF_STACK
[0x66de46] *Exception::CallStack::print_backtrace:Nil +118 in bin/ahk_x11.dev
[0x61a334] __crystal_raise +52 in bin/ahk_x11.dev
[0x62c461] ?? +6472801 in bin/ahk_x11.dev
[0x62c3e7] ?? +6472679 in bin/ahk_x11.dev
[0x76f05f] *Thread#main_fiber:Fiber +63 in bin/ahk_x11.dev
[0x76db52] *Crystal::Scheduler#initialize<Thread>:Deque(Fiber) +34 in bin/ahk_x11.dev
[0x76db21] *Crystal::Scheduler::new<Thread>:Crystal::Scheduler +129 in bin/ahk_x11.dev
[0x76eff5] *Thread#scheduler:Crystal::Scheduler +53 in bin/ahk_x11.dev
[0x76dc0e] *Crystal::Scheduler::event_loop:Crystal::EventLoop+ +14 in bin/ahk_x11.dev
[0x7704c6] *Crystal::EventLoop::current:Crystal::EventLoop+ +6 in bin/ahk_x11.dev
[0x7c3fa6] *File +6 in bin/ahk_x11.dev
[0x7c490a] *File +10 in bin/ahk_x11.dev
[0x7c48fc] *File +28 in bin/ahk_x11.dev
[0x7c3d77] *File +103 in bin/ahk_x11.dev
[0xa4c68a] *Compiler#finalize:Nil +10 in bin/ahk_x11.dev
[0x6454e6] ~proc11Proc(Pointer(Void), Pointer(Void), Nil) +6 in bin/ahk_x11.dev
[0x7fd38c9d70df] GC_invoke_finalizers +79 in /usr/lib/libgc.so.1
[0x7fd38c9d730e] ?? +140546573955854 in /usr/lib/libgc.so.1
[0x7fd38c9e2095] GC_generic_malloc +37 in /usr/lib/libgc.so.1
[0x7fd38c9e23d7] GC_malloc_kind_global +295 in /usr/lib/libgc.so.1
[0x6f8ece] *GC::malloc<UInt64>:Pointer(Void) +62 in bin/ahk_x11.dev
[0x6198de] __crystal_malloc64 +14 in bin/ahk_x11.dev
[0x76ba6c] *Fiber::new<Pointer(Void), Thread>:Fiber +28 in bin/ahk_x11.dev
[0x76f35f] *Thread#start:(Exception+ | Nil) +63 in bin/ahk_x11.dev
[0x63de86] ~procProc(Pointer(Void), Pointer(Void)) +6 in bin/ahk_x11.dev
[0x7fd38c9f098e] ?? +140546574059918 in /usr/lib/libgc.so.1
[0x7fd38c9ee349] GC_call_with_stack_base +41 in /usr/lib/libgc.so.1
[0x7fd38b479ded] ?? +140546551553517 in /usr/lib/libc.so.6
[0x7fd38b4fd0dc] ?? +140546552090844 in /usr/lib/libc.so.6
[0x0] ???

Tried to raise:: Thread#main_fiber cannot be nil (NilAssertionError)
Unable to load dwarf information: Thread#main_fiber cannot be nil (NilAssertionError)
  from bin/ahk_x11.dev in 'Exception::CallStack::unwind:Array(Pointer(Void))'
  from bin/ahk_x11.dev in 'Exception::CallStack#initialize:Array(Pointer(Void))'
  from bin/ahk_x11.dev in 'Exception::CallStack::new:Exception::CallStack'
  from bin/ahk_x11.dev in 'raise<NilAssertionError>:NoReturn'
  from bin/ahk_x11.dev in 'Thread#main_fiber:Fiber'
  from bin/ahk_x11.dev in 'Crystal::Scheduler#initialize<Thread>:Deque(Fiber)'
  from bin/ahk_x11.dev in 'Crystal::Scheduler::new<Thread>:Crystal::Scheduler'
  from bin/ahk_x11.dev in 'Thread#scheduler:Crystal::Scheduler'
  from bin/ahk_x11.dev in 'Crystal::Scheduler::event_loop:Crystal::EventLoop+'
  from bin/ahk_x11.dev in 'Crystal::EventLoop::current:Crystal::EventLoop+'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'Exception::CallStack::read_dwarf_sections<String, UInt64>:(Array(Tuple(UInt64, UInt64, String)) | Nil)'
  from bin/ahk_x11.dev in 'Exception::CallStack::load_debug_info_impl:Nil'
  from bin/ahk_x11.dev in 'Exception::CallStack::load_debug_info:Nil'
  from bin/ahk_x11.dev in 'Exception::CallStack::decode_line_number<UInt64>:Tuple(String, Int32, Int32)'
  from bin/ahk_x11.dev in 'Exception::CallStack#decode_backtrace:Array(String)'
  from bin/ahk_x11.dev in 'Exception::CallStack#printable_backtrace:Array(String)'
  from bin/ahk_x11.dev in 'Exception+'
  from bin/ahk_x11.dev in 'Crystal::System::print_exception<String, Exception+>:Nil'
  from bin/ahk_x11.dev in '__crystal_raise'
  from bin/ahk_x11.dev in '??'
  from bin/ahk_x11.dev in '??'
  from bin/ahk_x11.dev in 'Thread#main_fiber:Fiber'
  from bin/ahk_x11.dev in 'Crystal::Scheduler#initialize<Thread>:Deque(Fiber)'
  from bin/ahk_x11.dev in 'Crystal::Scheduler::new<Thread>:Crystal::Scheduler'
  from bin/ahk_x11.dev in 'Thread#scheduler:Crystal::Scheduler'
  from bin/ahk_x11.dev in 'Crystal::Scheduler::event_loop:Crystal::EventLoop+'
  from bin/ahk_x11.dev in 'Crystal::EventLoop::current:Crystal::EventLoop+'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'Compiler#finalize:Nil'
  from bin/ahk_x11.dev in '~proc11Proc(Pointer(Void), Pointer(Void), Nil)'
  from /usr/lib/libgc.so.1 in 'GC_invoke_finalizers'
  from /usr/lib/libgc.so.1 in '??'
  from /usr/lib/libgc.so.1 in 'GC_generic_malloc'
  from /usr/lib/libgc.so.1 in 'GC_malloc_kind_global'
  from bin/ahk_x11.dev in 'GC::malloc<UInt64>:Pointer(Void)'
  from bin/ahk_x11.dev in '__crystal_malloc64'
  from bin/ahk_x11.dev in 'Fiber::new<Pointer(Void), Thread>:Fiber'
  from bin/ahk_x11.dev in 'Thread#start:(Exception+ | Nil)'
  from bin/ahk_x11.dev in '~procProc(Pointer(Void), Pointer(Void))'
  from /usr/lib/libgc.so.1 in '??'
  from /usr/lib/libgc.so.1 in 'GC_call_with_stack_base'
  from /usr/lib/libc.so.6 in '??'
  from /usr/lib/libc.so.6 in '??'
  from ???
  from bin/ahk_x11.dev in 'Exception::CallStack::unwind:Array(Pointer(Void))'
  from bin/ahk_x11.dev in 'Exception::CallStack#initialize:Array(Pointer(Void))'
  from bin/ahk_x11.dev in 'Exception::CallStack::new:Exception::CallStack'
  from bin/ahk_x11.dev in 'raise<NilAssertionError>:NoReturn'
  from bin/ahk_x11.dev in 'Thread#main_fiber:Fiber'
  from bin/ahk_x11.dev in 'Crystal::Scheduler#initialize<Thread>:Deque(Fiber)'
  from bin/ahk_x11.dev in 'Crystal::Scheduler::new<Thread>:Crystal::Scheduler'
  from bin/ahk_x11.dev in 'Thread#scheduler:Crystal::Scheduler'
  from bin/ahk_x11.dev in 'Crystal::Scheduler::event_loop:Crystal::EventLoop+'
  from bin/ahk_x11.dev in 'Crystal::EventLoop::current:Crystal::EventLoop+'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'File'
  from bin/ahk_x11.dev in 'Compiler#finalize:Nil'
  from bin/ahk_x11.dev in '~proc11Proc(Pointer(Void), Pointer(Void), Nil)'
  from /usr/lib/libgc.so.1 in 'GC_invoke_finalizers'
  from /usr/lib/libgc.so.1 in '??'
  from /usr/lib/libgc.so.1 in 'GC_generic_malloc'
  from /usr/lib/libgc.so.1 in 'GC_malloc_kind_global'
  from bin/ahk_x11.dev in 'GC::malloc<UInt64>:Pointer(Void)'
  from bin/ahk_x11.dev in '__crystal_malloc64'
  from bin/ahk_x11.dev in 'Fiber::new<Pointer(Void), Thread>:Fiber'
  from bin/ahk_x11.dev in 'Thread#start:(Exception+ | Nil)'
  from bin/ahk_x11.dev in '~procProc(Pointer(Void), Pointer(Void))'
  from /usr/lib/libgc.so.1 in '??'
  from /usr/lib/libgc.so.1 in 'GC_call_with_stack_base'
  from /usr/lib/libc.so.6 in '??'
  from /usr/lib/libc.so.6 in '??'
  from ???

I have no idea what this is and how to fix it, so I'll downgrade to Crystal 1.11 for the time being. Likely related to the fiber run override in hacks.cr

[donovanglover]

Is this fixable with 1.15? Seems like a lot has changed since crystal-lang/crystal@c3eb0eb

[donovanglover]

Builds for me when removing the custom Fiber code:

AHK_X11/src/hacks.cr

Lines 50 to 88 in 66eb520

	# https://github.com/crystal-lang/crystal/issues/13297
	class Fiber
	# Code copied over and extended from stdlib
	def run
	GC.unlock_read
	@proc.call
	rescue ex
	if handler = Hacks.fiber_on_unhandled_exception
	handler.call ex
	else
	if name = @name
	STDERR.print "Unhandled exception in spawn (name: #{name}): "
	else
	STDERR.print "Unhandled exception in spawn: "
	end
	ex.inspect_with_backtrace(STDERR)
	STDERR.flush
	end
	ensure
	{% if flag?(:preview_mt) %}
	Crystal::Scheduler.enqueue_free_stack @stack
	{% elsif flag?(:interpreted) %}
	# For interpreted mode we don't need a new stack, the stack is held by the interpreter
	{% else %}
	Fiber.stack_pool.release(@stack)
	{% end %}
	# Remove the current fiber from the linked list
	Fiber.fibers.delete(self)
	# Delete the resume event if it was used by `yield` or `sleep`
	@resume_event.try &.free
	@timeout_event.try &.free
	@timeout_select_action = nil
	@alive = false
	Crystal::Scheduler.reschedule
	end
	end

Seems like some wait_readable changes broke ./src/run/display/x11.cr in 1.15 which is another issue. Looks like they were internal APIs not meant to be used by users.

[phil294]

Thanks for looking this up. this is unfortunate, but I can't be bothered to chase after a replacement for something that was needlessly removed. If the Crystal team decides to break stuff, I'd rather just fix version 1.11 in place, never upgrade again and be done with it.