String msg = "Results sent from server=" + noOfResults + ". But
only got " + i + " results completely at client. Resetting the
scanner to scan again."; LOG.error(msg); throw new
DoNotRetryIOException(msg); } } catch (IOException ioe) {
// We are getting IOE while retrieving the cells for Results.
// We have to scan for the same results again. Throwing DNRIOE as a client
retry on the // same scanner will result in
OutOfOrderScannerNextException LOG.error("Exception while reading
cells from result." + "Resetting the scanner to scan again.",
ioe); throw new DoNotRetryIOException("Resetting the scanner.",
ioe); } cells.add(cellScanner.current());
System.out.println("ResponseConverter.getResults(1)--cells == "+ cells + "--j
== " + j + "---noOfCells == " + noOfCells); } results[i] =
Result.create(cells, null, response.getStale(), isPartial);
System.out.println("ResponseConverter.getResults(2)--cells == "+ cells +
"--results[i] == " + results[i] + "---noOfCells == " + noOfCells); } else
{ // Result is pure pb. results[i] =
ProtobufUtil.toResult(response.getResults(i));
System.out.println("ResponseConverter.getResults(3)--results == " + results[i]
+ "--i == " + i); } } return results; thank you very much, anoop, do
you want to see this code, the exception should occur on the red mark line.
----- 原始邮件 -----
发件人："ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
收件人：issues@hbase.apache.org
主题：[jira] [Updated] (HBASE-16643) Reverse scanner heap creation may not allow
MSLAB closure due to improper ref counting of segments
日期：2016年09月23日 13点25分
[
https://issues.apache.org/jira/browse/HBASE-16643?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
ramkrishna.s.vasudevan updated HBASE-16643:
-------------------------------------------
Status: Open (was: Patch Available)
> Reverse scanner heap creation may not allow MSLAB closure due to improper ref
> counting of segments
> --------------------------------------------------------------------------------------------------
>
> Key: HBASE-16643
> URL: https://issues.apache.org/jira/browse/HBASE-16643
> Project: HBase
> Issue Type: Bug
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Priority: Critical
> Fix For: 2.0.0
>
> Attachments: HBASE-16643.patch, HBASE-16643_1.patch,
> HBASE-16643_2.patch, HBASE-16643_3.patch, HBASE-16643_4.patch,
> HBASE-16643_5.patch
>
>
> In the reverse scanner case,
> While doing 'initBackwardHeapIfNeeded' in MemstoreScanner for setting the
> backward heap, we do a
> {code}
> if ((backwardHeap == null) && (forwardHeap != null)) {
> forwardHeap.close();
> forwardHeap = null;
> // before building the heap seek for the relevant key on the scanners,
> // for the heap to be built from the scanners correctly
> for (KeyValueScanner scan : scanners) {
> if (toLast) {
> res |= scan.seekToLastRow();
> } else {
> res |= scan.backwardSeek(cell);
> }
> }
> {code}
> forwardHeap.close(). This would internally decrement the MSLAB ref counter
> for the current active segment and snapshot segment.
> When the scan is actually closed again we do close() and that will again
> decrement the count. Here chances are there that the count would go negative
> and hence the actual MSLAB closure that checks for refCount==0 will fail.
> Apart from this, when the refCount becomes 0 after the firstClose if any
> other thread requests to close the segment, then we will end up in corrupted
> segment because the segment could be put back to the MSLAB pool.
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