junfei liang created HBASE-23277:
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Summary: CompactedHFilesDischarger may lead to high cpu usage
Key: HBASE-23277
URL: https://issues.apache.org/jira/browse/HBASE-23277
Project: HBase
Issue Type: Brainstorming
Reporter: junfei liang
Attachments: compated_discharger.png
in one of online cluster(RS:16C72G, hbase version is 2.x) , cpu average usage
is 30%, but cpu usage may above 80% occasionally. by a enchanced 'top -H'
script, i find 'RS_COMPACTED_FILES_DISCHARGER' threads can use 50%+ cpu ( 10
* 80% ).
!compated_discharger.png|width=1168,height=454!
by jstack , we found most of stacks is at.
"org.apache.hadoop.hbase.io.hfile.LruBlockCache#evictBlocksByHfileName"
public int evictBlocksByHfileName(String hfileName) {
int numEvicted = 0;
for (BlockCacheKey key : map.keySet()) {
if (key.getHfileName().equals(hfileName)) {
if (evictBlock(key))
++numEvicted;
}
}
if (victimHandler != null) {
numEvicted += victimHandler.evictBlocksByHfileName(hfileName);
}
return numEvicted;
}
when close storefile, now we evict it's blocks from cache, but we have to
traverse the whole blockcache to locate the block cached, and can lead to high
cpu usage.
do we need evict blockcache when close file, even for a small file ( size less
than 10MB)? it's a lru block cache, the unused block will be automatically
removed from cache when blockcache usage is high?
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