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https://issues.apache.org/jira/browse/HBASE-18451?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16379372#comment-16379372
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Jean-Marc Spaggiari commented on HBASE-18451:
---------------------------------------------
Ping. Can we get this re-based and commited somehow?
> PeriodicMemstoreFlusher should inspect the queue before adding a delayed
> flush request
> --------------------------------------------------------------------------------------
>
> Key: HBASE-18451
> URL: https://issues.apache.org/jira/browse/HBASE-18451
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 2.0.0-alpha-1
> Reporter: Jean-Marc Spaggiari
> Assignee: nihed mbarek
> Priority: Major
> Attachments: HBASE-18451.master.patch
>
>
> If you run a big job every 4 hours, impacting many tables (they have 150
> regions per server), ad the end all the regions might have some data to be
> flushed, and we want, after one hour, trigger a periodic flush. That's
> totally fine.
> Now, to avoid a flush storm, when we detect a region to be flushed, we add a
> "randomDelay" to the delayed flush, that way we spread them away.
> RANGE_OF_DELAY is 5 minutes. So we spread the flush over the next 5 minutes,
> which is very good.
> However, because we don't check if there is already a request in the queue,
> 10 seconds after, we create a new request, with a new randomDelay.
> If you generate a randomDelay every 10 seconds, at some point, you will end
> up having a small one, and the flush will be triggered almost immediatly.
> As a result, instead of spreading all the flush within the next 5 minutes,
> you end-up getting them all way more quickly. Like within the first minute.
> Which not only feed the queue to to many flush requests, but also defeats the
> purpose of the randomDelay.
> {code}
> @Override
> protected void chore() {
> final StringBuffer whyFlush = new StringBuffer();
> for (Region r : this.server.onlineRegions.values()) {
> if (r == null) continue;
> if (((HRegion)r).shouldFlush(whyFlush)) {
> FlushRequester requester = server.getFlushRequester();
> if (requester != null) {
> long randomDelay = RandomUtils.nextInt(RANGE_OF_DELAY) +
> MIN_DELAY_TIME;
> LOG.info(getName() + " requesting flush of " +
> r.getRegionInfo().getRegionNameAsString() + " because " +
> whyFlush.toString() +
> " after random delay " + randomDelay + "ms");
> //Throttle the flushes by putting a delay. If we don't throttle,
> and there
> //is a balanced write-load on the regions in a table, we might
> end up
> //overwhelming the filesystem with too many flushes at once.
> requester.requestDelayedFlush(r, randomDelay, false);
> }
> }
> }
> }
> {code}
> {code}
> 2017-07-24 18:44:33,338 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 270785ms
> 2017-07-24 18:44:43,328 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 200143ms
> 2017-07-24 18:44:53,954 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 191082ms
> 2017-07-24 18:45:03,528 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 92532ms
> 2017-07-24 18:45:14,201 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 238780ms
> 2017-07-24 18:45:24,195 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 35390ms
> 2017-07-24 18:45:33,362 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 283034ms
> 2017-07-24 18:45:43,933 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 84328ms
> 2017-07-24 18:45:53,866 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 72291ms
> 2017-07-24 18:46:03,329 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 62658ms
> 2017-07-24 18:46:14,084 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 87491ms
> 2017-07-24 18:46:23,538 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 290170ms
> 2017-07-24 18:46:33,353 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 228541ms
> 2017-07-24 18:46:43,359 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 211814ms
> 2017-07-24 18:46:54,150 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 155167ms
> 2017-07-24 18:47:03,546 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 115318ms
> 2017-07-24 18:47:13,350 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 216662ms
> 2017-07-24 18:47:23,329 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 96018ms
> 2017-07-24 18:47:33,891 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 144751ms
> 2017-07-24 18:47:43,329 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 152461ms
> 2017-07-24 18:47:53,832 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 97352ms
> 2017-07-24 18:48:03,348 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 263910ms
> 2017-07-24 18:48:13,353 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 151793ms
> 2017-07-24 18:48:23,340 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 61926ms
> 2017-07-24 18:48:33,724 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 188901ms
> 2017-07-24 18:48:44,038 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 233148ms
> 2017-07-24 18:48:53,624 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 6206ms
> 2017-07-24 18:49:03,378 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer:
> hbasetest2.domainname.com,60020,1500916375517-MemstoreFlusherChore requesting
> flush of testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. because f
> has an old edit so flush to free WALs after random delay 240946ms
> 2017-07-24 18:49:04,125 INFO org.apache.hadoop.hbase.regionserver.HRegion:
> Flushing 1/1 column families, memstore=160 B
> 2017-07-24 18:49:04,182 INFO
> org.apache.hadoop.hbase.regionserver.DefaultStoreFlusher: Flushed,
> sequenceid=6, memsize=160, hasBloomFilter=true, into tmp file
> hdfs://hbasetest1.domainname.com:8020/hbase/data/default/testflush/578c27d2eb7ef0ad437bf2ff38c053ae/.tmp/3609340d58ae4ca190e62c3b0fe415f4
> 2017-07-24 18:49:04,208 INFO org.apache.hadoop.hbase.regionserver.HStore:
> Added
> hdfs://hbasetest1.domainname.com:8020/hbase/data/default/testflush/578c27d2eb7ef0ad437bf2ff38c053ae/f/3609340d58ae4ca190e62c3b0fe415f4,
> entries=1, sequenceid=6, filesize=1015
> 2017-07-24 18:49:04,212 INFO org.apache.hadoop.hbase.regionserver.HRegion:
> Finished memstore flush of ~160 B/160, currentsize=0 B/0 for region
> testflush,,1500932649126.578c27d2eb7ef0ad437bf2ff38c053ae. in 87ms,
> sequenceid=6, compaction requested=false
> {code}
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