Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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2.0.0-alpha-1
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None
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Reviewed
Description
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.
@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);
}
}
}
}
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