This is an example project to reproduce this issue: golang/go#55015

The project contains two folders. Both of them contain the exact same code: a (not so) small example of an application scanning for BLE devices using the WinRT BLE APIs.

Both applications start a BLE scan operation, and wait indefinitely. Windows will execute the callback everytime a device is found.

The only difference is that one of them uses malloc to allocate memory into the heap, and thus, uses CGO. And the other one uses HeapAlloc via syscall, so it does not need CGO.

Note

example-malloc is pointing to the latest release of https://github.com/saltosystems/winrt-go, which uses malloc for allocation of delegates. example-heapalloc is pointing to this PR saltosystems/winrt-go#60, which replaces it for the HeapAlloc function.

Expected behaviour

Both applications should list the address of the devices they find.

What really happens

• example-malloc is working as expected: listing the address of the bluetooth devices it scans.
• example-heapalloc is failing with the following error:

fatal error: all goroutines are asleep - deadlock!

goroutine 1 [chan receive]:
main.runExample()
        C:/projects/go-deadlock-example/example-heapalloc/main.go:79 +0x3ee
main.main()
        C:/projects/go-deadlock-example/example-heapalloc/main.go:14 +0x19 
exit status 2

If you add a goroutine to example-heapalloc, then it works as expected. Even if the goroutine does nothing but wait:

go func() {
    <-time.After(5 * time.Second)
}()

This issue seems related to golang/go#6751