alex-plekhanov commented on a change in pull request #7245: IGNITE-12530 Pages
list cache limit added to prevent IgniteOOME on checkpoint
URL: https://github.com/apache/ignite/pull/7245#discussion_r366812927
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File path:
modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/GridCacheOffheapManager.java
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@@ -118,6 +120,19 @@
* Used when persistence enabled.
*/
public class GridCacheOffheapManager extends IgniteCacheOffheapManagerImpl
implements DbCheckpointListener {
+ /**
+ * Threshold to calculate limit for pages list on-heap caches.
+ * <p>
+ * Note: When a checkpoint is triggered, we need some amount of page
memory to store pages list on-heap cache.
+ * If a checkpoint is triggered by "too many dirty pages" reason and pages
list cache is rather big, we can get
+ * {@code IgniteOutOfMemoryException}. To prevent this, we can limit the
total amount of cached page list buckets,
+ * assuming that checkpoint will be triggered if no more then 3/4 of pages
will be marked as dirty (there will be
+ * at least 1/4 of clean pages) and each cached page list bucket can be
stored to up to 2 pages (this value is not
+ * static, but depends on PagesCache.MAX_SIZE, so if PagesCache.MAX_SIZE >
PagesListNodeIO#getCapacity it can take
+ * more than 2 pages). Also some amount of page memory needed to store
page list metadata.
+ */
+ public static final double PAGE_LIST_CACHE_LIMIT_THRESHOLD = 0.1;
Review comment:
1/4 (clean pages) / 2 (at most 2 pages per bucket cache) + some reserve for
metadata.
It's hard to calculate it dynamically, it depends on metadata size (which we
don't know at runtime)
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