[
https://issues.apache.org/jira/browse/HBASE-12728?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14270150#comment-14270150
]
stack commented on HBASE-12728:
-------------------------------
BufferedMutator or AsyncMutator seems better yes.
Is this intended; i.e. that we will flush after each Put or List<Put>? Isn't
point that we do not flush unless this method is called?
82 /**
83 * Executes all the buffered {@link Put} operations.
84 * <p>
85 * This method gets called once automatically for every {@link Put}
or batch
86 * of {@link Put}s (when <code>put(List<Put>)</code> is used) when
87 * @throws IOException if a remote or network exception occurs.
88 */
89 void flushCommits() throws IOException;
I'd say remove this from Interface:
100 /**
101 * Sets the size of the buffer in bytes.
102 * <p>
103 * If the new size is less than the current amount of data in the
104 * write buffer, the buffer gets flushed.
105 * @param writeBufferSize The new write buffer size, in bytes.
106 * @throws IOException if a remote or network exception occurs.
107 */
108 void setWriteBufferSize(long writeBufferSize) throws IOException;
Get a new instance if you want to change buffer size post-construction.
This should not be public, right? i.e. the constructor... needs to be shut down
because you get one from Connection?
64 public HBulkMutator(TableName tableName,
Skimmed the rest. Some of the changes seem a little gratuitous (refactoring by
your IDE?) so unnecessarily bloats your patch.
That is great that you move HTable on to the new stuff.
On the DoNothingLock, its for testing? Put it in test package?
Nice.
> buffered writes substantially less useful after removal of HTablePool
> ---------------------------------------------------------------------
>
> Key: HBASE-12728
> URL: https://issues.apache.org/jira/browse/HBASE-12728
> Project: HBase
> Issue Type: Bug
> Components: hbase
> Affects Versions: 0.98.0
> Reporter: Aaron Beppu
> Assignee: Solomon Duskis
> Priority: Blocker
> Fix For: 1.0.0, 2.0.0, 1.1.0
>
> Attachments: 12728.connection-owns-buffers.example.branch-1.0.patch,
> bulk-mutator.patch
>
>
> In previous versions of HBase, when use of HTablePool was encouraged, HTable
> instances were long-lived in that pool, and for that reason, if autoFlush was
> set to false, the table instance could accumulate a full buffer of writes
> before a flush was triggered. Writes from the client to the cluster could
> then be substantially larger and less frequent than without buffering.
> However, when HTablePool was deprecated, the primary justification seems to
> have been that creating HTable instances is cheap, so long as the connection
> and executor service being passed to it are pre-provided. A use pattern was
> encouraged where users should create a new HTable instance for every
> operation, using an existing connection and executor service, and then close
> the table. In this pattern, buffered writes are substantially less useful;
> writes are as small and as frequent as they would have been with
> autoflush=true, except the synchronous write is moved from the operation
> itself to the table close call which immediately follows.
> More concretely :
> ```
> // Given these two helpers ...
> private HTableInterface getAutoFlushTable(String tableName) throws
> IOException {
> // (autoflush is true by default)
> return storedConnection.getTable(tableName, executorService);
> }
> private HTableInterface getBufferedTable(String tableName) throws IOException
> {
> HTableInterface table = getAutoFlushTable(tableName);
> table.setAutoFlush(false);
> return table;
> }
> // it's my contention that these two methods would behave almost identically,
> // except the first will hit a synchronous flush during the put call,
> and the second will
> // flush during the (hidden) close call on table.
> private void writeAutoFlushed(Put somePut) throws IOException {
> try (HTableInterface table = getAutoFlushTable(tableName)) {
> table.put(somePut); // will do synchronous flush
> }
> }
> private void writeBuffered(Put somePut) throws IOException {
> try (HTableInterface table = getBufferedTable(tableName)) {
> table.put(somePut);
> } // auto-close will trigger synchronous flush
> }
> ```
> For buffered writes to actually provide a performance benefit to users, one
> of two things must happen:
> - The writeBuffer itself shouldn't live, flush and die with the lifecycle of
> it's HTableInstance. If the writeBuffer were managed elsewhere and had a long
> lifespan, this could cease to be an issue. However, if the same writeBuffer
> is appended to by multiple tables, then some additional concurrency control
> will be needed around it.
> - Alternatively, there should be some pattern for having long-lived HTable
> instances. However, since HTable is not thread-safe, we'd need multiple
> instances, and a mechanism for leasing them out safely -- which sure sounds a
> lot like the old HTablePool to me.
> See discussion on mailing list here :
> http://mail-archives.apache.org/mod_mbox/hbase-user/201412.mbox/%3CCAPdJLkEzmUQZ_kvD%3D8mrxi4V%3DhCmUp3g9MUZsddD%2Bmon%2BAvNtg%40mail.gmail.com%3E
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
