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https://issues.apache.org/jira/browse/HDDS-8129?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17698680#comment-17698680
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Tsz-wo Sze commented on HDDS-8129:
----------------------------------
The following is the code:
{code}
//ContainerStateMachine
private CompletableFuture<ContainerCommandResponseProto> submitTask(
ContainerCommandRequestProto request, DispatcherContext.Builder context,
Consumer<Exception> exceptionHandler) {
final long containerId = request.getContainerID();
final TaskQueue queue = containerTaskQueues.computeIfAbsent(
containerId, id -> new TaskQueue("container" + id));
final CheckedSupplier<ContainerCommandResponseProto, Exception> task
= () -> {
try {
return runCommand(request, context.build());
} catch (Exception e) {
exceptionHandler.accept(e);
throw e;
}
};
final CompletableFuture<ContainerCommandResponseProto> f
= queue.submit(task, executor);
// after the task is completed, remove the queue if the queue is empty.
f.thenAccept(dummy -> containerTaskQueues.computeIfPresent(containerId,
(id, q) -> q.isEmpty() ? null : q));
return f;
}
{code}
> ContainerStateMachine allows two different tasks with the same container id
> running in parallel
> -----------------------------------------------------------------------------------------------
>
> Key: HDDS-8129
> URL: https://issues.apache.org/jira/browse/HDDS-8129
> Project: Apache Ozone
> Issue Type: Bug
> Components: Ozone Datanode
> Reporter: Tsz-wo Sze
> Assignee: Tsz-wo Sze
> Priority: Blocker
>
> In the ContainerStateMachine.submitTask(..) method, we can have the following
> case
> # The applyTransaction thread enters submitTask(..). It gets a queue Q for a
> container C from containerTaskQueues, where Q is empty at that time.
> # Right before applyTransaction submits a task T1, the executor has
> completed running a previous task T2 for container C. Since Q is empty, so
> the executor removes Q from containerTaskQueues.
> # The applyTransaction thread submits task T1 to Q. It does not aware Q is
> not in containerTaskQueues anymore.
> # Now, the applyTransaction thread submits a new task T3 for container C.
> Since there is no queue for container C in containerTaskQueues, it creates a
> new queue Q2. Then, it submits T3 to Q2.
> As a result, T1 and T3 for container C can run in parallel since there are
> two queues.
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