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https://issues.apache.org/jira/browse/HBASE-8541?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13681390#comment-13681390
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Ted Yu commented on HBASE-8541:
-------------------------------
{code}
+ public boolean doFlushToL0() {
+ return flushIntoL0;
{code}
doFlushToL0 sounds like the method would do the actual flushing. Please rename.
{code}
- private class CompactionResultsMergeCopy {
+ private class CompactionOrFlushMergeCopy {
{code}
Mind updating javadoc for the above method w.r.t. flushing ?
{code}
+ if (isFlush) {
+ long newSize =
StripeCompactionPolicy.getTotalFileSize(newStripes.values());
+ LOG.error("Stripes were created by a flush, but results of size "
+ newSize
+ + " cannot be added due to a concurrent flush also creating
stripes");
+ canAddNewStripes = false;
+ filesForL0 = newStripes.values();
{code}
In code above, newStripes is put in filesForL0 - meaning we ignore
conflictingFiles. But the error message says that newSize cannot be added. This
seems to be inconsistent, right ?
{code}
+public class StripeStoreFlusher extends StoreFlusher {
+ private static final Log LOG = LogFactory.getLog(DefaultStoreFlusher.class);
{code}
Add audience annotation.
Log gets wrong class.
{code}
+ } finally {
+ if (!success && (mw != null)) {
+ result.clear();
+ for (StoreFile.Writer writer : mw.getAllWriters()) {
+ if (writer == null) continue;
+ writer.close();
{code}
You may want to catch IOException w.r.t. writer.close() call.
{code}
+ if (scanner == null) {
+ return null; // NULL from coprocessor here means skip normal processing
+ }
+ return scanner;
{code}
'return scanner' should be good enough for above.
{code}
+ * @param targetCount The maximum number of stripes to flush into.
+ * @param targetKvs The KV count of each segment. If targetKvs*targetCount
is less than
{code}
Can the above two parameters get better names ? How about targetStripeCount and
targetKvsPerStripe ?
> implement flush-into-stripes in stripe compactions
> --------------------------------------------------
>
> Key: HBASE-8541
> URL: https://issues.apache.org/jira/browse/HBASE-8541
> Project: HBase
> Issue Type: Improvement
> Reporter: Sergey Shelukhin
> Attachments: HBASE-8541-latest-with-dependencies.patch,
> HBASE-8541-v0.patch
>
>
> Flush will be able to flush into multiple files under this design, avoiding
> L0 I/O amplification.
> I have the patch which is missing just one feature - support for concurrent
> flushes and stripe changes. This can be done via extensive try-locking of
> stripe changes and flushes, or advisory flags without blocking flushes,
> dumping conflicting flushes into L0 in case of (very rare) collisions. For
> file loading for the latter, a set-cover-like problem needs to be solved to
> determine optimal stripes. That will also address Jimmy's concern of getting
> rid of metadata, btw. However currently I don't have time for that. I plan to
> attach the try-locking patch first, but this won't happen for a couple weeks
> probably and should not block main reviews. Hopefully this will be added on
> top of main reviews.
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