[
https://issues.apache.org/jira/browse/ARTEMIS-2224?focusedWorklogId=183633&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-183633
]
ASF GitHub Bot logged work on ARTEMIS-2224:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 10/Jan/19 09:59
Start Date: 10/Jan/19 09:59
Worklog Time Spent: 10m
Work Description: franz1981 commented on pull request #2494: ARTEMIS-2224
Reduce contention on LivePageCacheImpl
URL: https://github.com/apache/activemq-artemis/pull/2494#discussion_r246602031
##########
File path:
artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/LivePageCacheImpl.java
##########
@@ -48,54 +82,228 @@ public long getPageId() {
}
@Override
- public synchronized int getNumberOfMessages() {
- return messages.size();
+ public int getNumberOfMessages() {
+ while (true) {
+ final long size = producerIndex;
+ if (size == RESIZING) {
+ Thread.yield();
+ continue;
+ }
+ return (int) Math.min(size, Integer.MAX_VALUE);
+ }
}
@Override
- public synchronized void setMessages(PagedMessage[] messages) {
+ public void setMessages(PagedMessage[] messages) {
// This method shouldn't be called on liveCache, but we will provide the
implementation for it anyway
for (PagedMessage msg : messages) {
addLiveMessage(msg);
}
}
@Override
- public synchronized PagedMessage getMessage(int messageNumber) {
- if (messageNumber < messages.size()) {
- return messages.get(messageNumber);
- } else {
+ public PagedMessage getMessage(int messageNumber) {
+ if (messageNumber < 0) {
return null;
}
+ //it allow to perform less cache invalidations vs producerIndex if there
are bursts of appends
+ long size = lastSeenProducerIndex;
+ if (messageNumber >= size) {
+ while ((size = producerIndex) == RESIZING) {
+ Thread.yield();
+ }
+ //it is a message over the current size?
+ if (messageNumber >= size) {
Review comment:
Is not that easy here, this one is not a common collection (in theory, but
we can get an agreement on the contract for sure): it is more an append only
list that allows indexed queries like a map. In addition, is concurrent so if
you try to query something that's not in the collection in that moment, but you
will do it right after, there is a chance that you can get it if it has been
added in parallel by another thread.
If I remember correctly it is similar to an [hashed array
tree](https://en.wikipedia.org/wiki/Hashed_array_tree), where the top-level
directory is a double linked list of "folders" (instead of an array, like the
original implementation): indeed in the code there are chunkIndex (==key of top
level directory) and offset (==key of leaf into a directory).
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
Issue Time Tracking
-------------------
Worklog Id: (was: 183633)
Time Spent: 10m
Remaining Estimate: 0h
> Reduce contention on LivePageCacheImpl
> --------------------------------------
>
> Key: ARTEMIS-2224
> URL: https://issues.apache.org/jira/browse/ARTEMIS-2224
> Project: ActiveMQ Artemis
> Issue Type: Improvement
> Components: Broker
> Affects Versions: 2.7.0
> Reporter: Francesco Nigro
> Assignee: Francesco Nigro
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Has been measured that LIvePageCacheImpl operations are a source of
> contention on producer side while paging.
> This contention decrease the scalability of the broker in an evident way
> while using topics, because the page cache is been accessed concurrently by
> several producers to ack transactions while the messages are being appended.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
