hanging when setting boardsize to 9 after initialzing

[versed mirage]

I have been writing a gui with python which hosts katago and shows moves. This is for children beginners to play go so that its strength should be 30k - 20k. One task is to simulate the followings:
katago gtp -config gtp_human5k_example.cfg -model network.bin.gz -human-model b18c384nbt-humanv0.bin.gz
It is not hard to implement this one with python subprocess, but the default boardsize is 19. 19x19 board is too big for children. after initialzing trying to set boardsize 9 cause hanging. What causes hanging?

def send_command_boardsize(self, command):
    """Send the boardsize command and log all output."""
    if self.process.poll() is not None:
        print("Engine process has terminated.")
        return None

    print(f"Sending command: {command}")
    try:
        self.process.stdin.write(command + "\n")
        self.process.stdin.flush()
    except OSError as e:
        print(f"Error sending command '{command}': {e}")
        return None

    response_lines = []
    while True:
        line = self.process.stdout.readline().strip()
        if line:
            print(f"Received line: {line}")  # Log each line
            response_lines.append(line)
            if line == "=":  # Stop reading when the final confirmation is received
                break

    return "\n".join(response_lines)

[thorn sun]

what is command set to?

[versed mirage]

send_command_boardsize("boardsize 9") # using the above methd.

[thorn sun]

So iirc one thing that occurs when sending a board size change is that the neural network must be reinitialized. Is the hanging you are experiencing just this? (Check stderr)

[versed mirage]

I do not know whether the neuralnet is reinitialzed (though on the command line case it seems to reinitialze). I believe haning occurs during the processing of the above method.

[thorn sun]

Do you ever consume stderr? If not, the text written to stderr might have filled up the buffer and the engine process is blocking on writing diagnostic information to the pipe.

You should try to consume stderr and either throw it away or log it to a file or something

[versed mirage]

You're right. On adding error consuming routine, setting board size seems to be sucessful. I can see full of text output like those shown in the command line. For this progress I thank you a lot. However, this time the engine does not generate a move. It can take a huma move but do not give its own move. How do I figure out this problem? Some tip please.

[thorn sun]

So for clarity, you play a move, such as by writing play black E5\n to stdin. Then you receive a response from the engine from stdout which might look like =2.

Then you issue genmove white\n and the engine hangs without error or diagnostic?

[thorn sun]

(if the above is correct, does this also happen if you put several play commands back to back?)

[modern holly]

More accurately, it is “genmove white”.

[thorn sun]

My bad

Fixed