Expecting a panic on max queued tasks

[cannero]

In the chapter 'Applied: Build an Executor' we set MAX_QUEUED_TASKS and have an expect on send(task) which should fail if there are too many tasks. I tried to trigger this panic by setting MAX_QUEUED_TASKS to 1 and spawn the async function for TimerFuture two times. However the program just hangs. By setting the max queued tasks to 2, it works.

I'm on windows, if it helps here is the stack trace for the main thread:

[0x0] ntdll!NtWaitForAlertByThreadId + 0x14
[0x1] ntdll!RtlSleepConditionVariableSRW + 0x130
[0x2] KERNELBASE!SleepConditionVariableSRW + 0x2d
[0x3] async_prog!std::sys::windows::c::SleepConditionVariableSRW + 0x3e
[0x4] async_prog!std::sys::windows::condvar::Condvar::wait + 0x3e
[0x5] async_prog!std::sys_common::condvar::Condvar::wait + 0x3e
[0x6] async_prog!std::sync::condvar::Condvar::wait + 0x58
[0x7] async_prog!std::thread::park + 0x1ab
[0x8] async_prog!std::sync::mpsc::blocking::WaitToken::wait + 0x25
[0x9] async_prog!std::sync::mpsc::sync::Packet<alloc::sync::Arc<async_prog::simple_executor::Task>>::acquire_send_slot<alloc::sync::Arc<async_prog::simple_executor::Task>> + 0x19d
[0xa] async_prog!std::sync::mpsc::sync::Packet<alloc::sync::Arc<async_prog::simple_executor::Task>>::send<alloc::sync::Arc<async_prog::simple_executor::Task>> + 0x48
[0xb] async_prog!std::sync::mpsc::SyncSender<alloc::sync::Arc<async_prog::simple_executor::Task>>::send<alloc::sync::Arc<async_prog::simple_executor::Task>> + 0x42
[0xc] async_prog!async_prog::simple_executor::Spawner::spawn<std::future::GenFuture> + 0xad
[0xd] async_prog!async_prog::use_timer_future + 0x9b
[0xe] async_prog!async_prog::main::{{closure}} + 0x36
[0xf] async_prog!std::future::{{impl}}::poll::{{closure}} + 0x1d
[0x10] async_prog!std::future::set_task_context<closure-1,core::task::poll::Poll<()>> + 0x73
[0x11] async_prog!std::future::{{impl}}::poll + 0x36
[0x12] async_prog!tokio::runtime::enter::Enter::block_on<std::future::GenFuture> + 0x15e
[0x13] async_prog!tokio::runtime::thread_pool::ThreadPool::block_on<std::future::GenFuture> + 0x44
[0x14] async_prog!tokio::runtime::{{impl}}::block_on::{{closure}}<std::future::GenFuture> + 0xb7
[0x15] async_prog!tokio::runtime::context::enter<closure-0,()> + 0x6b
[0x16] async_prog!tokio::runtime::handle::Handle::enter<closure-0,()> + 0x56
[0x17] async_prog!tokio::runtime::Runtime::block_on<std::future::GenFuture> + 0x47
[0x18] async_prog!async_prog::main + 0xbd
[0x19] async_prog!std::rt::lang_start::{{closure}}<()> + 0x10
[0x1a] async_prog!std::rt::lang_start_internal::{{closure}} + 0xc
[0x1b] async_prog!std::panicking::try::do_call<closure-0,i32> + 0x17
[0x1c] async_prog!panic_unwind::__rust_maybe_catch_panic + 0x22
[0x1d] async_prog!std::panicking::try + 0x33
[0x1e] async_prog!std::panic::catch_unwind + 0x33
[0x1f] async_prog!std::rt::lang_start_internal + 0x102
[0x20] async_prog!std::rt::lang_start<()> + 0x3b
[0x21] async_prog!main + 0x20
[0x22] async_prog!invoke_main + 0x22
[0x23] async_prog!__scrt_common_main_seh + 0x10c
[0x24] KERNEL32!BaseThreadInitThunk + 0x14
[0x25] ntdll!RtlUserThreadStart + 0x21

[honzuki]

The program hangs because the thread gets into a deadlock. I fixed it at #189