Weird stdout/stderr indefinite loop with vala async exec / pipe example

I tried out the example about exec and spawning, when running this with vala or compiling with valac, I get an endless loop of the output below. Is that normal? Incidentally, this is on OS X, normally I am on Linux and I can test it later on Linux.
Vala version 0.40.9 installed with brew, using glib version 2.58.0 also installed with brew.

out: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stderr: (null)stdout: (null)stde


Edit: When running the same example on Ubuntu Xenial it worked as expected, but it is also using vala 0.30.1 by default. Is that just a way too old version? But at least now I saw what the example should look like.

Edit2: The code used is 'Spawn with pipes, async' from https://valadoc.org/glib-2.0/GLib.Process.spawn_async_with_pipes.html without any modifications, just copy pasted.

private static bool process_line (IOChannel channel, IOCondition condition, string stream_name)
if (condition == IOCondition.HUP)
print ("%s: The fd has been closed.n", stream_name);
return false;


try
string line;
channel.read_line (out line, null, null);
print ("%s: %s", stream_name, line);
catch (IOChannelError e)
print ("%s: IOChannelError: %sn", stream_name, e.message);
return false;
catch (ConvertError e)
print ("%s: ConvertError: %sn", stream_name, e.message);
return false;


return true;


public static int main (string args)
MainLoop loop = new MainLoop ();
try
string spawn_args = "ls", "-l", "-h";
string spawn_env = Environ.get ();
Pid child_pid;

int standard_input;
int standard_output;
int standard_error;

Process.spawn_async_with_pipes ("/",
spawn_args,
spawn_env,
SpawnFlags.SEARCH_PATH catch (SpawnError e)
print ("Error: %sn", e.message);

return 0;



The bug report is here: https://gitlab.gnome.org/GNOME/glib/issues/1512

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