[jira] [Updated] (IGNITE-12096) Used memory metric does not contract when cache is emptied - FreeList REUSE_BUCKET is not accounted for

["Nikolay Izhikov (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-12096?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nikolay Izhikov updated IGNITE-12096:
-------------------------------------
    Fix Version/s:     (was: 2.8.1)

> Used memory metric does not contract when cache is emptied - FreeList REUSE_BUCKET is not accounted for
> -------------------------------------------------------------------------------------------------------
>
>                 Key: IGNITE-12096
>                 URL: https://issues.apache.org/jira/browse/IGNITE-12096
>             Project: Ignite
>          Issue Type: Bug
>          Components: cache
>    Affects Versions: 2.7
>            Reporter: Colin Cassidy
>            Priority: Major
>             Fix For: 2.9
>
>
> When using the Ignite metrics API to measure available memory, the usage figures appear to be accurate while memory is being consumed - but when memory is freed the metrics do not drop. They appear to report that memory has not been freed up, even though it has.
> A reliable estimate of memory consumption is very important for solutions that don't use native persistence - as this is the only controllable way of avoiding a critical OOM condition.
> Reproducer below. This affects Ignite 2.7+.
> {{public class MemoryTest2 { }}
> {{    private static final String CACHE_NAME = "cache"; }}
>  {{    private static final String DEFAULT_MEMORY_REGION = "Default_Region"; }}
>  {{    private static final long MEM_SIZE = 100L * 1024 * 1024; }}
> {{    @Test }}
>  {{    public void testOOM() throws InterruptedException { }}
>  {{        try (Ignite ignite = startIgnite("IgniteMemoryMonitorTest1")) { }}
>  {{            fillDataRegion(ignite); }}
>  {{            CacheConfiguration<Object, Object> cfg = new }}
>  {{CacheConfiguration<>(CACHE_NAME); }}
>  {{            cfg.setStatisticsEnabled(true); }}
>  {{            IgniteCache<Object, Object> cache = }}
>  {{ignite.getOrCreateCache(cfg); }}
> {{            // Clear all entries from the cache to free up memory }}
>  {{            memUsed(ignite); }}
>  {{            cache.clear(); }}
>  {{            cache.removeAll(); }}
>  {{            cache.put("Key", "Value"); }}
>  {{            memUsed(ignite); }}
>  {{            cache.destroy(); }}
>  {{            Thread.sleep(5000); }}
> {{            // Should now report close to 0% but reports 59% still }}
>  {{            memUsed(ignite); }}
>  {{        } }}
>  {{    } }}
>  {{    }}
>  {{    private Ignite startIgnite(String instanceName) { }}
>  {{        IgniteConfiguration cfg = new IgniteConfiguration(); }}
>  {{        cfg.setIgniteInstanceName(instanceName); }}
>  {{        cfg.setDataStorageConfiguration(createDataStorageConfiguration()); }}
>  {{        cfg.setFailureHandler(new NoOpFailureHandler()); }}
>  {{        return Ignition.start(cfg); }}
>  {{    } }}
> {{    private DataStorageConfiguration createDataStorageConfiguration() { }}
>  {{        return new DataStorageConfiguration() }}
>  {{                .setDefaultDataRegionConfiguration( }}
>  {{                        new DataRegionConfiguration() }}
>  {{                                .setName(DEFAULT_MEMORY_REGION) }}
>  {{                                .setInitialSize(MEM_SIZE) }}
>  {{                                .setMaxSize(MEM_SIZE) }}
>  {{                                .setMetricsEnabled(true)); }}
>  {{    } }}
> {{    private void fillDataRegion(Ignite ignite) { }}
>  {{        byte[] megabyte = new byte[1024 * 1024]; }}
>  {{            IgniteCache<Object, Object> cache = }}
>  {{                    ignite.getOrCreateCache(CACHE_NAME); }}
>  {{            for (int i = 0; i < 50; i++) { }}
>  {{                cache.put(i, megabyte); }}
>  {{                memUsed(ignite); }}
>  {{            } }}
>  {{    } }}
> {{    private void memUsed(Ignite ignite) { }}
>  {{        DataRegionConfiguration defaultDataRegionCfg = }}
>  {{ignite.configuration() }}
>  {{                .getDataStorageConfiguration() }}
>  {{                .getDefaultDataRegionConfiguration(); }}
>  {{        String regionName = defaultDataRegionCfg.getName(); }}
>  {{        DataRegionMetrics metrics = ignite.dataRegionMetrics(regionName); }}
>  {{        float usedMem = metrics.getPagesFillFactor() * }}
>  {{metrics.getTotalAllocatedPages() * metrics.getPageSize(); }}
>  {{        float pctUsed = 100 * usedMem / defaultDataRegionCfg.getMaxSize(); }}
>  {{        System.out.println("Memory used: " + pctUsed + "%"); }}
>  {{    } }}
>  {{} }}



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