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https://issues.apache.org/jira/browse/HBASE-6968?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13482173#comment-13482173
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liang xie commented on HBASE-6968:
----------------------------------
I look through trunk code, there's no change needed, so let's set this affects
issue version on 0.90/0.92/0.94 only, right ?
> Several HBase write perf improvement
> ------------------------------------
>
> Key: HBASE-6968
> URL: https://issues.apache.org/jira/browse/HBASE-6968
> Project: HBase
> Issue Type: Improvement
> Reporter: Liyin Tang
>
> Here are 2 hbase write performance improvements recently:
> 1) Avoid creating HBaseConfiguraiton object for each HLog. Every time when
> creating a HBaseConfiguraiton object, it would parse the xml configuration
> files from disk, which is not cheap operation.
> In HLog.java:
> orig:
> {code:title=HLog.java}
> newWriter = createWriter(fs, newPath, HBaseConfiguration.create(conf));
> {code}
> new:
> {code}
> newWriter = createWriter(fs, newPath, conf);
> {code}
> 2) Change 2 hotspot synchronized functions into double locking pattern. So it
> shall remove the synchronization overhead in the normal case.
> orig:
> {code:title=HBaseRpcMetrics.java}
> public synchronized void inc(String name, int amt) {
> MetricsTimeVaryingRate m = get(name);
> if (m == null) {
> m = create(name);
> }
> m.inc(amt);
> }
> {code}
> new:
> {code}
> public void inc(String name, int amt) {
> MetricsTimeVaryingRate m = get(name);
> if (m == null) {
> synchronized (this) {
> if ((m = get(name)) == null) {
> m = create(name);
> }
> }
> }
> m.inc(amt);
> }
> {code}
> =====================
> orig:
> {code:title=MemStoreFlusher.java}
> public synchronized void reclaimMemStoreMemory() {
> if (this.server.getGlobalMemstoreSize().get() >= globalMemStoreLimit) {
> flushSomeRegions();
> }
> }
> {code}
> new:
> {code}
> public void reclaimMemStoreMemory() {
> if (this.server.getGlobalMemstoreSize().get() >= globalMemStoreLimit) {
> flushSomeRegions();
> }
> }
> private synchronized void flushSomeRegions() {
> if (this.server.getGlobalMemstoreSize().get() < globalMemStoreLimit) {
> return; // double check the global memstore size inside of the
> synchronized block.
> }
> ...
> }
> {code}
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