ApsaraMQ for RabbitMQ:Best practices for instance throttling

The following operations are performed after throttling is triggered:

• The ApsaraMQ for RabbitMQ broker returns an error code and an error message. For more information, see Error codes.

• The ApsaraMQ for RabbitMQ broker closes the channel of the current request. You can detect exceptions in the code and reopen the channel.

Sample Java code for throttling:

private static final int MAX_RETRIES = 5; // The maximum number of retries.
private static final long WAIT_TIME_MS = 2000; // The wait time between two consecutive retries. Unit: milliseconds.

private void doAnythingWithReopenChannels(Connection connection, Channel channel) {
    try {
        // ......
        // Any operation performed in the current channel.
        // The operation can be message sending or message consumption.
        // ......

    } catch (AlreadyClosedException e) {
        String message = e.getMessage();
        if (isChannelClosed(message)) {
            // If the channel is closed, close and re-create the channel.
            channel = createChannelWithRetry(connection); 
            // Continue to perform other operations after reconnection.
            // ......
        } else {
            throw e;
        }
    }
}

private Channel createChannelWithRetry(Connection connection) {
    for (int attempt = 1; attempt <= MAX_RETRIES; attempt++) {
        try {
            return connection.createChannel();
        } catch (Exception e) {
            System.err.println("Failed to create channel. Attempt " + attempt + " of " + MAX_RETRIES);
            // Check for errors. If the channel is still closed due to throttling, you can wait and try again.
            // You can also remove the retry logic in this part.
            if (attempt < MAX_RETRIES) {
                try {
                    Thread.sleep(WAIT_TIME_MS);
                } catch (InterruptedException ie) {
                    Thread.currentThread().interrupt(); // Reset the thread to the interrupted state.
                }
            } else {
                throw new RuntimeException("Exceeded maximum retries to create channel", e);
            }
        }
    }
    throw new RuntimeException("This line should never be reached"); // In theory, this step cannot be reached.
}

private boolean isChannelClosed(String errorMsg) {
    // Determine whether the channel.close error is reported. The error indicates that the channel is closed. 
    // Error codes, such as 530 and 541, may be included. 
    if (errorMsg != null && errorMsg.contains("channel.close")) {
        System.out.println("[ChannelClosed] Error details: " + errorMsg);
        return true;
    }
    return false;
}