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_r280542595
##########
File path:
artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/PageCursorProviderImpl.java
##########
@@ -132,52 +146,99 @@ 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);
+ }
+ }
+ if (createPage) {
+ return readPage(pageId, page, cache, inProgressReadPage);
+ } else {
+ final long startedWait = System.nanoTime();
+ while (true) {
+ try {
+ return
inProgressReadPage.get(CONCURRENT_PAGE_READ_TIMEOUT_NS, TimeUnit.NANOSECONDS);
+ } catch (TimeoutException e) {
+ final long elapsed = System.nanoTime() - startedWait;
+ final long elapsedMillis =
TimeUnit.NANOSECONDS.toMillis(elapsed);
+ logger.warnf("Waiting a concurrent Page::read for pageNr=%d
on cursor %s by %d ms",
+ pageId, pagingStore.getAddress(),
elapsedMillis);
+ }
}
}
-
- return cache;
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}
- private void readPage(int pageId, PageCache cache) throws Exception {
- Page page = null;
+ private PageCache readPage(long pageId,
+ Page page,
+ PageCache cache,
+ CompletableFuture<PageCache> inProgressReadPage)
throws Exception {
+ logger.tracef("adding pageCache pageNr=%d into cursor = %s", pageId,
this.pagingStore.getAddress());
+ boolean acquiredPageReadPermission = false;
try {
- page = pagingStore.createPage(pageId);
-
- storageManager.beforePageRead();
+ final long startedRequest = System.nanoTime();
+ while (!acquiredPageReadPermission) {
+ acquiredPageReadPermission =
storageManager.beforePageRead(PAGE_READ_PERMISSION_TIMEOUT_NS,
TimeUnit.NANOSECONDS);
+ if (!acquiredPageReadPermission) {
+ final long elapsedMillis =
TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startedRequest);
+ logger.warnf("Cannot acquire page read permission of pageNr=%d
on cursor %s after %d ms: consider increasing page-max-concurrent-io or use a
faster disk",
+ pageId, pagingStore.getAddress(), elapsedMillis);
+ }
+ }
page.open();
-
+ final long startedReadPage = System.nanoTime();
List<PagedMessage> pgdMessages = page.read(storageManager);
+ final long elapsedReadPage = System.nanoTime() - startedReadPage;
+ if (elapsedReadPage > PAGE_READ_TIMEOUT_NS) {
+ logger.warnf("Page::read for pageNr=%d on cursor %s tooks %d ms to
read %d bytes", pageId,
Review comment:
@clebertsuconic @jbertram
In order to not modify `Page::read` and introduce a whole new "failure"
state (half pages read with critical IO error raised)
I've preferred to add some more detailed logs in order to detect weird
behaviours, long wait or `page-max-concurrent-io` misconfigurations.
I suppose that adding a proper "slowness disk/JVM suicide" deserve its own
PR.
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