Eviction is not Happening for dataregion persistence=true
kagrawal-tibco opened this issue · 8 comments
We want limited cache functionality for persistence = true and data should be evicted as per PageReplacement policy used . But currently data is not evicting and project throws outOfMemoryException.
I am attaching the sample project/class to depict the same You can use the project or simply change the cacheTrasaction example file in ignite examples and change the REGION_40MB_EVICTION = "40MB_Region_Eviction" in example-data-regions.xml config file to enable persistence and page Replacement policy.
This is created by modifying one of Ingite's shipped examples : cacheTrasactionExample.java class and the example-data-regions.xml to enable persistence. You can see for persistence disabled it is working fine and can see from logs data is evicting properly if cache.put() call is used.
persistence =true ,pageReplacementMode = SEGMENTED_LRU
Cache transaction example started.
DatastorageConfig40MB_Region_Eviction SEGMENTED_LRU0.9 null
DatastorageConfig30MB_Region_Swapping CLOCK0.9 null
[2024-08-03T11:34:16,656][ERROR][checkpoint-runner-cpu-#97][] Critical system error detected. Will be handled accordingly to configured handler [hnd=StopNodeOrHaltFailureHandler [tryStop=false, timeout=0, super=AbstractFailureHandler [ignoredFailureTypes=UnmodifiableSet [SYSTEM_WORKER_BLOCKED, SYSTEM_CRITICAL_OPERATION_TIMEOUT]]], failureCtx=FailureContext [type=CRITICAL_ERROR, err=class o.a.i.i.mem.IgniteOutOfMemoryException: Out of memory in data region [name=40MB_Region_Eviction, initSize=12.0 MiB, maxSize=15.0 MiB, persistenceEnabled=true] Try the following:
^-- Increase maximum off-heap memory size (DataRegionConfiguration.maxSize)
^-- Enable eviction or expiration policies]]
org.apache.ignite.internal.mem.IgniteOutOfMemoryException: Out of memory in data region [name=40MB_Region_Eviction, initSize=12.0 MiB, maxSize=15.0 MiB, persistenceEnabled=true] Try the following:
^-- Increase maximum off-heap memory size (DataRegionConfiguration.maxSize)
^-- Enable eviction or expiration policies
at org.apache.ignite.internal.processors.cache.persistence.pagemem.PageMemoryImpl.allocatePage(PageMemoryImpl.java:654) ~[ignite-core-2.15.0.jar:2.15.0]
persistence = false
Accounts a deposit:
Account [id=1, balance=$100.0]
Account [id=2, balance=$200.0]
Accounts after transfer:
Account [id=20, balance=$100.0]
null
Cache transaction example finished.
Accounts after transfer:
Account [id=20, balance=$100.0]
Account [id=1005, balance=$100.0]
Cache transaction example finished.
Accounts after transfer:
Account [id=20, balance=$100.0]
Account [id=1005, balance=$100.0]
Cache transaction example finished.
Accounts after transfer:
null
null
Cache transaction example finished.
Eviction does not work with native persistence, see https://ignite.apache.org/docs/latest/memory-configuration/eviction-policies
Eviction is used in following cases:
- for off-heap memory when Native Persistence is off;
- for off-heap memory when Ignite is used with an external storage;
- for on-heap caches;
- for near caches if configured.
When Native Persistence is on, a similar process — called page replacement — is used to free up off-heap memory when Ignite cannot allocate a new page. The difference is that the data is not lost (because it is stored in the persistent storage), and therefore you are less concerned about losing data than about efficiency. Refer to the Replacement Policies page for information about page replacement configuration.
Configure Page Replacement instead: https://ignite.apache.org/docs/latest/memory-configuration/replacement-policies
Hi @ptupitsyn thank you for the quick response if you see I have enabled the page replacement policy as well in the config file. the policy used is SEGMENTED_LRU.
You are right, did not notice this initially. I've tried your code and it fails for me too.
I think 40 MB is just too small for page replacement to work properly - there are not enough pages overall.
If I change maxSize to 400 MB, the error does not occur, and we can see that there is more data on disk than in RAM:
[12:19:33] ^-- 40MB_Region_Eviction region [type=user, persistence=true, lazyAlloc=true,
[12:19:33] ... initCfg=100MB, maxCfg=400MB, usedRam=392MB, freeRam=1.95%, allocRam=400MB, allocTotal=886MB]
Thank you for your response yes for higher memory it works with 100 MB . So is there any lower limit to this?
You can probably achieve a lower limit by making the page size smaller.
Can I ask you - what is the use case? Ignite is made for big data, a 40 MB data region might be suboptimal.
Sorry for late response .We have ignite integration with our product and We give our customers to set the cache size and we wanted to confirm what is the minimum size after which there is no error . So updated that to a higher value for now
Thanks @ptupitsyn For all the help