HBASE-3855 Performance degradation of memstore because reseek is linear
git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1100236 13f79535-47bb-0310-9956-ffa450edef68
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@ -207,6 +207,8 @@ Release 0.91.0 - Unreleased
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(Harsh J Chouraria)
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HBASE-3835 Switch master and region server pages to Jamon-based templates
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HBASE-3721 Speedup LoadIncrementalHFiles (Ted Yu)
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HBASE-3855 Performance degradation of memstore because reseek is linear
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(dhruba borthakur)
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TASKS
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HBASE-3559 Move report of split to master OFF the heartbeat channel
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@ -62,6 +62,9 @@ public class MemStore implements HeapSize {
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"hbase.hregion.memstore.mslab.enabled";
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private static final boolean USEMSLAB_DEFAULT = false;
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static final String RESEEKMAX_KEY =
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"hbase.hregion.memstore.reseek.maxkeys";
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private static final int RESEEKMAX_DEFAULT = 32;
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private Configuration conf;
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@ -93,6 +96,11 @@ public class MemStore implements HeapSize {
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MemStoreLAB allocator;
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// if a reseek has to scan over more than these number of keys, then
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// it morphs into a seek. A seek does a tree map-search while
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// reseek does a linear scan.
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int reseekNumKeys;
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/**
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* Default constructor. Used for tests.
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*/
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@ -121,6 +129,7 @@ public class MemStore implements HeapSize {
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} else {
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this.allocator = null;
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}
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this.reseekNumKeys = conf.getInt(RESEEKMAX_KEY, RESEEKMAX_DEFAULT);
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}
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void dump() {
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@ -643,6 +652,9 @@ public class MemStore implements HeapSize {
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Iterator<KeyValue> kvsetIt;
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Iterator<KeyValue> snapshotIt;
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// number of iterations in this reseek operation
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int numIterReseek;
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/*
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Some notes...
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@ -678,6 +690,10 @@ public class MemStore implements HeapSize {
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// keep it.
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ret = v;
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}
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numIterReseek--;
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if (numIterReseek == 0) {
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break;
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}
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}
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return ret;
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}
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@ -687,6 +703,7 @@ public class MemStore implements HeapSize {
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close();
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return false;
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}
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numIterReseek = 0;
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// kvset and snapshot will never be empty.
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// if tailSet cant find anything, SS is empty (not null).
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@ -715,14 +732,27 @@ public class MemStore implements HeapSize {
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@Override
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public boolean reseek(KeyValue key) {
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numIterReseek = reseekNumKeys;
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while (kvsetNextRow != null &&
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comparator.compare(kvsetNextRow, key) < 0) {
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kvsetNextRow = getNext(kvsetIt);
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// if we scanned enough entries but still not able to find the
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// kv we are looking for, better cut our costs and do a tree
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// scan using seek.
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if (kvsetNextRow == null && numIterReseek == 0) {
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return seek(key);
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}
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}
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while (snapshotNextRow != null &&
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comparator.compare(snapshotNextRow, key) < 0) {
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snapshotNextRow = getNext(snapshotIt);
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// if we scanned enough entries but still not able to find the
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// kv we are looking for, better cut our costs and do a tree
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// scan using seek.
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if (snapshotNextRow == null && numIterReseek == 0) {
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return seek(key);
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}
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}
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return (kvsetNextRow != null || snapshotNextRow != null);
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}
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