[
https://issues.apache.org/jira/browse/FLINK-9676?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16538305#comment-16538305
]
ASF GitHub Bot commented on FLINK-9676:
---------------------------------------
Github user NicoK commented on a diff in the pull request:
https://github.com/apache/flink/pull/6254#discussion_r201273133
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/RemoteInputChannel.java
---
@@ -479,6 +508,9 @@ void onSenderBacklog(int backlog) throws IOException {
numRequiredBuffers = backlog + initialCredit;
while (bufferQueue.getAvailableBufferSize() <
numRequiredBuffers && !isWaitingForFloatingBuffers) {
+ // TODO: this will take a lock in the
LocalBufferPool as well and needs to be done
+ // outside the synchronized block (which is a
bit difficult trying to acquire the
+ // lock only once!
Buffer buffer =
inputGate.getBufferPool().requestBuffer();
--- End diff --
I'm not sure about this change since this may lead to lower-throughput
channels being starved by high-throughput channels, but we can discuss further
with a broader audience in the JIRA ticket once created (this is off-topic here)
> Deadlock during canceling task and recycling exclusive buffer
> -------------------------------------------------------------
>
> Key: FLINK-9676
> URL: https://issues.apache.org/jira/browse/FLINK-9676
> Project: Flink
> Issue Type: Bug
> Components: Network
> Affects Versions: 1.5.0
> Reporter: zhijiang
> Assignee: Nico Kruber
> Priority: Critical
> Labels: pull-request-available
> Fix For: 1.5.1, 1.6.0
>
>
> It may cause deadlock between task canceler thread and task thread.
> The detail is as follows:
> {{Task canceler thread -> IC1#releaseAllResources -> recycle floating buffers
> -> {color:#d04437}lock{color}(LocalBufferPool#availableMemorySegments) ->
> IC2#notifyBufferAvailable}} > {color:#d04437}try to
> lock{color}(IC2#bufferQueue)
> {{Task thread -> IC2#recycle -> {color:#d04437}lock{color}(IC2#bufferQueue)
> -> bufferQueue#addExclusiveBuffer}} -> {{floatingBuffer#recycleBuffer}} ->
> {color:#d04437}try to lock{color}(LocalBufferPool#availableMemorySegments)
> One solution is that {{listener#notifyBufferAvailable}} can be called outside
> the {{synchronized(availableMemorySegments) in }}{{LocalBufferPool#recycle.}}
> The existing RemoteInputChannelTest#testConcurrentOnSenderBacklogAndRecycle
> can cover this case but the deadlock probability is very low, so this UT is
> not stable.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
