diff --git a/docs/en/Example_Batch.md b/docs/en/Example_Batch.md new file mode 100644 index 0000000000000000000000000000000000000000..d7199ca7c78c03b02df56935ba8dcc31a7f02dfd --- /dev/null +++ b/docs/en/Example_Batch.md @@ -0,0 +1,76 @@ +# Batch Message Sample +------ +Sending messages in batch improves performance of delivering small messages. Messages of the same batch should have: same topic, same waitStoreMsgOK and no schedule support. You can send messages up to 4MiB at a time, but if you need to send a larger message, it is recommended to divide the larger messages into multiple small messages of no more than 1MiB. +### 1 Send Batch Messages +If you just send messages of no more than 4MiB at a time, it is easy to use batch: +```java +String topic = "BatchTest"; +List messages = new ArrayList<>(); +messages.add(new Message(topic, "TagA", "OrderID001", "Hello world 0".getBytes())); +messages.add(new Message(topic, "TagA", "OrderID002", "Hello world 1".getBytes())); +messages.add(new Message(topic, "TagA", "OrderID003", "Hello world 2".getBytes())); +try { + producer.send(messages); +} catch (Exception e) { + e.printStackTrace(); + //handle the error +} +``` +### 2 Split into Lists +The complexity only grow when you send large batch and you may not sure if it exceeds the size limit (4MiB). At this time, you’d better split the lists: +```java +public class ListSplitter implements Iterator> { + private final int SIZE_LIMIT = 1000 * 1000; + private final List messages; + private int currIndex; + public ListSplitter(List messages) { + this.messages = messages; + } + @Override public boolean hasNext() { + return currIndex < messages.size(); + } + @Override public List next() { + int nextIndex = currIndex; + int totalSize = 0; + for (; nextIndex < messages.size(); nextIndex++) { + Message message = messages.get(nextIndex); + int tmpSize = message.getTopic().length() + message.getBody().length; + Map properties = message.getProperties(); + for (Map.Entry entry : properties.entrySet()) { + tmpSize += entry.getKey().length() + entry.getValue().length(); + } + tmpSize = tmpSize + 20; //for log overhead + if (tmpSize > SIZE_LIMIT) { + //it is unexpected that single message exceeds the SIZE_LIMIT + //here just let it go, otherwise it will block the splitting process + if (nextIndex - currIndex == 0) { + //if the next sublist has no element, add this one and then break, otherwise just break + nextIndex++; + } + break; + } + if (tmpSize + totalSize > SIZE_LIMIT) { + break; + } else { + totalSize += tmpSize; + } + + } + List subList = messages.subList(currIndex, nextIndex); + currIndex = nextIndex; + return subList; + } +} + +// then you could split the large list into small ones: +ListSplitter splitter = new ListSplitter(messages); +while (splitter.hasNext()) { + try { + List listItem = splitter.next(); + producer.send(listItem); + } catch (Exception e) { + e.printStackTrace(); + // handle the error + } +} +``` \ No newline at end of file