在单次读取操作中未接收到完整行时出现问题。如果接收到的数据的最后一个字符不是换行符，则意味着该行不完整。不完整的行将被存储以供下一次迭代使用，并且下一次读取操作将向其追加更多数据。然而，后续拆分操作仍可能导致处理不完整的行。

示例1.

不完整的行存储在incomplete_line变量中。该变量随着每次迭代而更新，以将不完整的线与接收到的新数据沿着累积。然后将组合的数据拆分成行，并处理除最后一行之外的所有完整行。最后一行被存储为可能不完整，用于下一次迭代。

def tail(filename: str, stop_event: Event):
    """
    Tails a file and pushes data into intake gateway.

    :param filename: full path to file
    :param stop_event: event used to send stop signal
    """
    with subprocess.Popen(
        [which("tail"), "-f", "-n", "0", quote(filename)],
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE
    ) as tail_process:
        logging.info("Creating tail process with PID '%s'", tail_process.pid)

        # Using 'DefaultSelector' as this is expected to run
        # on Linux and BSD systems
        selector = selectors.DefaultSelector()
        selector.register(tail_process.stdout, selectors.EVENT_READ)

        incomplete_line = ''
        # Loops when 'selector.select' times out, exits
        # when stop event is sent.
        while not stop_event.is_set():
            for key, _ in selector.select(timeout=5.0):
                # Read data from fileobj
                data = key.fileobj.read1().decode('utf-8')

                # Combine the incomplete line with the new data
                data = incomplete_line + data

                # Split the data into lines
                lines = data.split("\n")

                # Process all complete lines except the last one
                for line in lines[:-1]:
                    # Pushing each log line into mocked gateway function.
                    intake_gateway_push(line)

                # The last line might be incomplete, so store it for the next iteration
                incomplete_line = lines[-1]
                
        logging.info("Unregistering selector from tail PID '%s'", tail_process.pid)
        selector.unregister(tail_process.stdout)
        
        # Tail process is usually defunct and does not exit on OpenBSD7.3
        # explicity calling 'kill' solves this, need to investigate how
        # the context manager is cleaning up child processes.
        tail_process.kill()

示例2.

对于更有效的解决方案，您可以使用相同的过程，但不是收集不完整的行，而是以流式方式处理数据，并在可用时收集完整的行。
注：此解决方案假设数据以\n终止，因此请根据您的需要进行调整。

def tail(filename: str, stop_event: Event):
    """
    Tails a file and pushes data into intake gateway.

    :param filename: full path to file
    :param stop_event: event used to send stop signal
    """
    with subprocess.Popen(
        [which("tail"), "-f", "-n", "0", quote(filename)],
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE
    ) as tail_process:
        logging.info("Creating tail process with PID '%s'", tail_process.pid)

        # Using 'DefaultSelector' as this is expected to run
        # on Linux and BSD systems
        selector = selectors.DefaultSelector()
        selector.register(tail_process.stdout, selectors.EVENT_READ)

        incomplete_line = ''
        # Loops when 'selector.select' times out, exits
        # when stop event is sent.
        while not stop_event.is_set():
            for key, _ in selector.select(timeout=5.0):
                # Read data from fileobj
                data = key.fileobj.read1().decode('utf-8')

                # Combine the incomplete line with the new data
                data = incomplete_line + data
                
                # Process each character in the data
                start = 0
                for i in range(len(data)):
                    if data[i] == '\n':
                        # Process the complete line
                        line = data[start:i]
                        # Pushing the log line into mocked gateway function.
                        intake_gateway_push(line)
                        start = i + 1

                # The last line might be incomplete, so store it for the next iteration
                # incomplete_line = lines[-1]
                incomplete_line = data[start:]
                
        logging.info("Unregistering selector from tail PID '%s'", tail_process.pid)
        selector.unregister(tail_process.stdout)
        
        # Tail process is usually defunct and does not exit on OpenBSD7.3
        # explicity calling 'kill' solves this, need to investigate how
        # the context manager is cleaning up child processes.
        tail_process.kill()