frostruan commented on code in PR #4859:
URL: https://github.com/apache/hbase/pull/4859#discussion_r1011630652
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hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionScannerImpl.java:
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@@ -130,19 +130,34 @@ private static boolean hasNonce(HRegion region, long
nonce) {
long mvccReadPoint = PackagePrivateFieldAccessor.getMvccReadPoint(scan);
this.scannerReadPoints = region.scannerReadPoints;
this.rsServices = region.getRegionServerServices();
- synchronized (scannerReadPoints) {
- if (mvccReadPoint > 0) {
- this.readPt = mvccReadPoint;
- } else if (hasNonce(region, nonce)) {
- this.readPt =
rsServices.getNonceManager().getMvccFromOperationContext(nonceGroup, nonce);
- } else {
- this.readPt = region.getReadPoint(isolationLevel);
+ if (region.useReadWriteLockForReadPoints) {
+ region.scannerReadPointsLock.readLock().lock();
+ try {
+ this.readPt = calculateReadPoint(isolationLevel, mvccReadPoint,
nonceGroup, nonce);
+ scannerReadPoints.put(this, this.readPt);
Review Comment:
When we do delta operation like increment/append, we will need to get the
smallest read point.
If we both have heavy delta operation load and heavy read load, the write
lock may reduce the write performance. so let's introduce a flag to make this
decided by the user.
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