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Posted to commits@pulsar.apache.org by "codelipenghui (via GitHub)" <gi...@apache.org> on 2023/10/26 03:26:15 UTC
Re: [PR] [fix][client] Avert extensive time consumption during table view construction [pulsar]
codelipenghui commented on code in PR #21270:
URL: https://github.com/apache/pulsar/pull/21270#discussion_r1372529642
##########
pulsar-client/src/main/java/org/apache/pulsar/client/impl/TableViewImpl.java:
##########
@@ -235,20 +237,36 @@ private CompletableFuture<Reader<T>> readAllExistingMessages(Reader<T> reader) {
AtomicLong messagesRead = new AtomicLong();
CompletableFuture<Reader<T>> future = new CompletableFuture<>();
- readAllExistingMessages(reader, future, startTime, messagesRead);
+ reader.getLastMessageIdsAsync().thenAccept(lastMessageIds -> {
+ Map<String, TopicMessageId> maxMessageIds = new HashMap<>();
+ lastMessageIds.forEach(topicMessageId -> {
+ maxMessageIds.put(topicMessageId.getOwnerTopic(), topicMessageId);
+ });
+ readAllExistingMessages(reader, future, startTime, messagesRead, maxMessageIds);
Review Comment:
It's better to make `maxMessageIds` that passed to the `readAllExistingMessages` immutable to prohibit other threads from getting a chance to update the HashMap.
##########
pulsar-client/src/main/java/org/apache/pulsar/client/impl/TableViewImpl.java:
##########
@@ -235,20 +237,36 @@ private CompletableFuture<Reader<T>> readAllExistingMessages(Reader<T> reader) {
AtomicLong messagesRead = new AtomicLong();
CompletableFuture<Reader<T>> future = new CompletableFuture<>();
- readAllExistingMessages(reader, future, startTime, messagesRead);
+ reader.getLastMessageIdsAsync().thenAccept(lastMessageIds -> {
+ Map<String, TopicMessageId> maxMessageIds = new HashMap<>();
+ lastMessageIds.forEach(topicMessageId -> {
+ maxMessageIds.put(topicMessageId.getOwnerTopic(), topicMessageId);
+ });
+ readAllExistingMessages(reader, future, startTime, messagesRead, maxMessageIds);
+ });
Review Comment:
The exception from `reader.getLastMessageIdsAsync()` should be handled. Otherwise, the `future` will never get a chance to be complete.
##########
pulsar-client/src/main/java/org/apache/pulsar/client/impl/TableViewImpl.java:
##########
@@ -235,20 +237,36 @@ private CompletableFuture<Reader<T>> readAllExistingMessages(Reader<T> reader) {
AtomicLong messagesRead = new AtomicLong();
CompletableFuture<Reader<T>> future = new CompletableFuture<>();
- readAllExistingMessages(reader, future, startTime, messagesRead);
+ reader.getLastMessageIdsAsync().thenAccept(lastMessageIds -> {
+ Map<String, TopicMessageId> maxMessageIds = new HashMap<>();
+ lastMessageIds.forEach(topicMessageId -> {
+ maxMessageIds.put(topicMessageId.getOwnerTopic(), topicMessageId);
+ });
+ readAllExistingMessages(reader, future, startTime, messagesRead, maxMessageIds);
+ });
return future;
}
private void readAllExistingMessages(Reader<T> reader, CompletableFuture<Reader<T>> future, long startTime,
- AtomicLong messagesRead) {
+ AtomicLong messagesRead, Map<String, TopicMessageId> maxMessageIds) {
reader.hasMessageAvailableAsync()
.thenAccept(hasMessage -> {
if (hasMessage) {
reader.readNextAsync()
.thenAccept(msg -> {
messagesRead.incrementAndGet();
handleMessage(msg);
- readAllExistingMessages(reader, future, startTime, messagesRead);
+ // The message is read one by one in a single thread,
+ // so it's fine that uses a hashmap to store last message ID.
+ TopicMessageId maxMessageId = maxMessageIds.get(msg.getTopicName());
+ if (maxMessageId != null && msg.getMessageId().compareTo(maxMessageId) >= 0) {
+ maxMessageIds.remove(msg.getTopicName());
+ }
+ if (maxMessageIds.size() == 0) {
Review Comment:
nit
```suggestion
if (maxMessageIds.isEmpty()) {
```
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