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https://issues.apache.org/jira/browse/KAFKA-7707?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16718420#comment-16718420
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huangyiming commented on KAFKA-7707:
------------------------------------
Hi [~sliebau] ，thank you review, in the lock area,don't have another thread
add Condition to the waiters. the waiters only have one condition
{code:java}
public ByteBuffer allocate(int size, long maxTimeToBlockMs) throws
InterruptedException {
if (size > this.totalMemory)
throw new IllegalArgumentException("Attempt to allocate " + size
+ " bytes, but there is a hard limit of "
+ this.totalMemory
+ " on memory allocations.");
ByteBuffer buffer = null;
this.lock.lock();
try {
// check if we have a free buffer of the right size pooled
if (size == poolableSize && !this.free.isEmpty())
return this.free.pollFirst();
// now check if the request is immediately satisfiable with the
// memory on hand or if we need to block
int freeListSize = freeSize() * this.poolableSize;
if (this.nonPooledAvailableMemory + freeListSize >= size) {
// we have enough unallocated or pooled memory to immediately
// satisfy the request, but need to allocate the buffer
freeUp(size);
this.nonPooledAvailableMemory -= size;
} else {
// we are out of memory and will have to block
int accumulated = 0;
Condition moreMemory = this.lock.newCondition();
try {
long remainingTimeToBlockNs = TimeUnit.MILLISECONDS.toNanos(maxTimeToBlockMs);
this.waiters.addLast(moreMemory);
{code}
and finally we have remove the Condition:
{code:java}
} finally { // When this loop was not able to successfully terminate don't
loose available memory this.nonPooledAvailableMemory += accumulated;
this.waiters.remove(moreMemory); }
{code}
so i think in the last finally:
{code:java}
} finally { // signal any additional waiters if there is more memory left //
over for them try { if (!(this.nonPooledAvailableMemory == 0 &&
this.free.isEmpty()) && !this.waiters.isEmpty())
this.waiters.peekFirst().signal(); } finally { // Another finally... otherwise
find bugs complains lock.unlock(); } }
{code}
can modify like this:
{code:java}
} finally { lock.unlock(); }
{code}
> Some code is not necessary
> --------------------------
>
> Key: KAFKA-7707
> URL: https://issues.apache.org/jira/browse/KAFKA-7707
> Project: Kafka
> Issue Type: Improvement
> Reporter: huangyiming
> Priority: Minor
> Attachments: image-2018-12-05-18-01-46-886.png
>
>
> In the trunk branch in
> [BufferPool.java|https://github.com/apache/kafka/blob/578205cadd0bf64d671c6c162229c4975081a9d6/clients/src/main/java/org/apache/kafka/clients/producer/internals/BufferPool.java#L174],
> i think the code can clean,is not necessary,it will never execute
> {code:java}
> if (!(this.nonPooledAvailableMemory == 0 && this.free.isEmpty()) &&
> !this.waiters.isEmpty())
> this.waiters.peekFirst().signal();
> {code}
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