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https://issues.apache.org/jira/browse/CASSANDRA-8860?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14339773#comment-14339773
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Phil Yang commented on CASSANDRA-8860:
--------------------------------------

The heapdump is still being uploaded, I find these Entry objects is indeed 
generated by SizeTieredCompactionStrategy.createOverlapChain. So do you still 
need the heapdump?

Besides, in my cluster there are only two table with 
SizeTieredCompactionStrategy, one is System.paxos which has no data, the other 
has about 1100 tables in total.
{{
CREATE TABLE dict_voice.voice (
    key bigint PRIMARY KEY,
    data blob
) WITH COMPACT STORAGE
    AND bloom_filter_fp_chance = 0.1
    AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
    AND comment = ''
    AND compaction = {'min_threshold': '4', 'class': 
'org.apache.cassandra.db.compaction.LeveledCompactionStrategy', 
'max_threshold': '32'}
    AND compression = {'sstable_compression': 
'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND dclocal_read_repair_chance = 0.0
    AND default_time_to_live = 0
    AND gc_grace_seconds = 864000
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.0
    AND speculative_retry = '99.0PERCENTILE';
}}
SSTables in each level: [1, 10, 103/100, 904, 128, 0, 0, 0, 0]

> Too many java.util.HashMap$Entry objects in heap
> ------------------------------------------------
>
>                 Key: CASSANDRA-8860
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8860
>             Project: Cassandra
>          Issue Type: Bug
>         Environment: Cassandra 2.1.3, jdk 1.7u51
>            Reporter: Phil Yang
>            Assignee: Marcus Eriksson
>             Fix For: 2.1.4
>
>         Attachments: cassandra-env.sh, cassandra.yaml, jmap.txt, jstack.txt
>
>
> While I upgrading my cluster to 2.1.3, I find some nodes (not all) may have 
> GC issue after the node restarting successfully. Old gen grows very fast and 
> most of the space can not be recycled after setting its status to normal 
> immediately. The qps of both reading and writing are very low and there is no 
> heavy compaction.
> Jmap result seems strange that there are too many java.util.HashMap$Entry 
> objects in heap, where in my experience the "[B" is usually the No1.
> If I downgrade it to 2.1.1, this issue will not appear.
> I uploaded conf files and jstack/jmap outputs. I'll upload heap dump if 
> someone need it.



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