chia7712 commented on code in PR #18093:
URL: https://github.com/apache/kafka/pull/18093#discussion_r1874548857
##########
core/src/main/java/kafka/server/share/SharePartition.java:
##########
@@ -371,52 +370,35 @@ public static RecordState forId(byte id) {
*/
public CompletableFuture<Void> maybeInitialize() {
log.debug("Maybe initialize share partition: {}-{}", groupId,
topicIdPartition);
- CompletableFuture<Void> future = new CompletableFuture<>();
- AtomicReference<Optional<Throwable>> futureException = new
AtomicReference<>(Optional.empty());
// Check if the share partition is already initialized.
- InitializationResult initializationResult =
checkInitializationCompletion();
- if (initializationResult.isComplete()) {
- if (initializationResult.throwable() != null) {
- future.completeExceptionally(initializationResult.throwable());
- } else {
- future.complete(null);
+ try {
+ if (initializedOrThrowException()) {
+ return CompletableFuture.completedFuture(null);
}
- return future;
+ } catch (Exception e) {
+ return CompletableFuture.failedFuture(e);
}
+ // If code reaches here then the share partition is not initialized.
Initialize the share partition.
// All the pending requests should wait to get completed before the
share partition is initialized.
// Attain lock to avoid any concurrent requests to be processed.
lock.writeLock().lock();
- boolean shouldFutureBeCompleted = false;
try {
// Re-check the state to verify if previous requests has already
initialized the share partition.
- initializationResult = checkInitializationCompletion();
- if (initializationResult.isComplete()) {
- if (initializationResult.throwable() != null) {
-
futureException.set(Optional.of(initializationResult.throwable()));
- }
- shouldFutureBeCompleted = true;
- return future;
+ if (initializedOrThrowException()) {
+ return CompletableFuture.completedFuture(null);
Review Comment:
If a thread holds the write lock and the returned `CompletableFuture` is
registered to complete delayed operations, a deadlock could occur again.
However, this may not currently be an issue since we only call
`completeDelayedShareFetchRequest` when the future is done.
```java
CompletableFuture<Void> initializationFuture =
sharePartition.maybeInitialize();
final boolean initialized = initializationFuture.isDone();
initializationFuture.whenComplete((result, throwable) -> {
if (!initialized)
replicaManager.completeDelayedShareFetchRequest(delayedShareFetchKey);
});
```
However, I prefer not to hold the write lock while completing the future.
Perhaps we can add a new helper method to change the state from empty to
initializing.
```java
private boolean emptyToInitialState() {
lock.writeLock().lock();
try {
if (initializedOrThrowException()) return false;
partitionState = SharePartitionState.INITIALIZING;
return true;
} finally {
lock.writeLock().unlock();
}
}
```
Additionally, the second check can be simplified using the following style:
```java
// If code reaches here then the share partition is not initialized.
Initialize the share partition.
// All the pending requests should wait to get completed before the
share partition is initialized.
// Attain lock to avoid any concurrent requests to be processed.
try {
if (!emptyToInitialState()) return
CompletableFuture.completedFuture(null);
} catch (Exception e) {
return CompletableFuture.failedFuture(e);
}
```
##########
core/src/main/java/kafka/server/share/SharePartition.java:
##########
@@ -426,55 +408,50 @@ public CompletableFuture<Void> maybeInitialize() {
.build())
.build()
).whenComplete((result, exception) -> {
+ Throwable throwable = null;
lock.writeLock().lock();
try {
if (exception != null) {
log.error("Failed to initialize the share partition:
{}-{}", groupId, topicIdPartition, exception);
- completeInitializationWithException();
- futureException.set(Optional.of(exception));
+ throwable = exception;
return;
}
if (result == null || result.topicsData() == null ||
result.topicsData().size() != 1) {
log.error("Failed to initialize the share partition:
{}-{}. Invalid state found: {}.",
groupId, topicIdPartition, result);
- completeInitializationWithException();
- futureException.set(Optional.of(new
IllegalStateException(String.format("Failed to initialize the share partition
%s-%s", groupId, topicIdPartition))));
+ throwable = new
IllegalStateException(String.format("Failed to initialize the share partition
%s-%s", groupId, topicIdPartition));
return;
}
TopicData<PartitionAllData> state = result.topicsData().get(0);
if (state.topicId() != topicIdPartition.topicId() ||
state.partitions().size() != 1) {
log.error("Failed to initialize the share partition:
{}-{}. Invalid topic partition response: {}.",
groupId, topicIdPartition, result);
- completeInitializationWithException();
- futureException.set(Optional.of(new
IllegalStateException(String.format("Failed to initialize the share partition
%s-%s", groupId, topicIdPartition))));
+ throwable = new
IllegalStateException(String.format("Failed to initialize the share partition
%s-%s", groupId, topicIdPartition));
return;
}
PartitionAllData partitionData = state.partitions().get(0);
if (partitionData.partition() != topicIdPartition.partition())
{
log.error("Failed to initialize the share partition:
{}-{}. Invalid partition response: {}.",
groupId, topicIdPartition, partitionData);
- completeInitializationWithException();
- futureException.set(Optional.of(new
IllegalStateException(String.format("Failed to initialize the share partition
%s-%s", groupId, topicIdPartition))));
+ throwable = new
IllegalStateException(String.format("Failed to initialize the share partition
%s-%s", groupId, topicIdPartition));
return;
}
if (partitionData.errorCode() != Errors.NONE.code()) {
KafkaException ex =
fetchPersisterError(partitionData.errorCode(), partitionData.errorMessage());
log.error("Failed to initialize the share partition:
{}-{}. Exception occurred: {}.",
groupId, topicIdPartition, partitionData);
- completeInitializationWithException();
- futureException.set(Optional.of(ex));
+ throwable = ex;
return;
}
try {
startOffset =
startOffsetDuringInitialization(partitionData.startOffset());
} catch (Exception e) {
Review Comment:
Could we remove this nested try-cache by moving out of this "catch"? for
example:
```java
try {
...
} catch (Exception e) {
throwable = e;
} finally {
boolean isFailed = throwable != null;
...
}
```
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