franz1981 commented on a change in pull request #2645: ARTEMIS-2321 Paging
scalability and GC improvement
URL: https://github.com/apache/activemq-artemis/pull/2645#discussion_r279617994
##########
File path:
artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/PageCursorProviderImpl.java
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@@ -132,43 +156,88 @@ public PagedReference newReference(final PagePosition
pos,
@Override
public PageCache getPageCache(final long pageId) {
try {
+ if (pageId > pagingStore.getCurrentWritingPage()) {
+ return null;
+ }
+ boolean createPage = false;
+ CompletableFuture<PageCache> inProgressReadPage;
PageCache cache;
+ Page page = null;
synchronized (softCache) {
- if (pageId > pagingStore.getCurrentWritingPage()) {
+ cache = softCache.get(pageId);
+ if (cache != null) {
+ return cache;
+ }
+ if (!pagingStore.checkPageFileExists((int) pageId)) {
return null;
}
-
- cache = softCache.get(pageId);
- if (cache == null) {
- if (!pagingStore.checkPageFileExists((int) pageId)) {
- return null;
- }
-
+ inProgressReadPage = inProgressReadPages.get(pageId);
+ if (inProgressReadPage == null) {
+ final CompletableFuture<PageCache> readPage = new
CompletableFuture<>();
cache = createPageCache(pageId);
- // anyone reading from this cache will have to wait reading to
finish first
- // we also want only one thread reading this cache
- logger.tracef("adding pageCache pageNr=%d into cursor = %s",
pageId, this.pagingStore.getAddress());
- readPage((int) pageId, cache);
- softCache.put(pageId, cache);
+ page = pagingStore.createPage((int) pageId);
+ createPage = true;
+ inProgressReadPage = readPage;
+ inProgressReadPages.put(pageId, readPage);
}
}
+ //We need to create a new criticalComponent each time, because
+ //each read page action can happen from a different thread
+ final CriticalComponent readPageActionComponent;
+ if (criticalAnalyzer == null) {
+ readPageActionComponent = null;
+ } else {
+ final SimpleString address = pagingStore.getAddress();
+ readPageActionComponent = new
CriticalComponentImpl(criticalAnalyzer, PAGE_CURSOR_PROVIDER_CRITICAL_PATHS) {
Review comment:
I have no idea, maybe yes, but I don't want to make this code more complex
then necessary: consider that on each `Page::read` request we already create 1
`CompleableFuture` and each completed read will produce several Paged messages
as well.
Saving just 1 instance of CriticalComponentImpl maybe is not a super-win...
I'm more concerned from a functional point of view instead: in this version
I'm triggering the critical analyzer in both cases ie on Page::read and on who
is waiting for it.
Probably I can just leave the critical analyzer to monitor Page:.read and
logging otherwise.. @clebertsuconic wdyt?
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