Nick,
I tried what you suggested, 1 HConnection and 1 Configuration for the entire
app:
this.config = HBaseConfiguration.create();
this.connection = HConnectionManager.createConnection(config);
And Threaded pooled HTableInterfaces:
final HConnection lconnection = this.connection;
this.tlTable = new ThreadLocal<HTableInterface>() {
@Override
protected HTableInterface initialValue() {
try {
return lconnection.getTable("HBaseSerialWritesPOC");
// return new HTable(tlConfig.get(),
// "HBaseSerialWritesPOC");
} catch (IOException e) {
throw new RuntimeException(e);
}
}
};
I started getting this error in my application:
2015-02-26 10:23:17,833 INFO [main-SendThread(xxx)] zookeeper.ClientCnxn
(ClientCnxn.java:logStartConnect(966)) - Opening socket connection to server
xxx. Will not attempt to authenticate using SASL (unknown error)
2015-02-26 10:23:17,834 INFO [main-SendThread(xxx)] zookeeper.ClientCnxn
(ClientCnxn.java:primeConnection(849)) - Socket connection established to xxx,
initiating session
2015-02-26 10:23:17,836 WARN [main-SendThread(xxx)] zookeeper.ClientCnxn
(ClientCnxn.java:run(1089)) - Session 0x0 for server xxx, unexpected error,
closing socket connection and attempting reconnect
java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:192)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:379)
at org.apache.zookeeper.ClientCnxnSocketNIO.doIO(ClientCnxnSocketNIO.java:68)
at
org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:355)
at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1068)
-Marcelo
From: [email protected]
Subject: Re: HBase connection pool
Okay, looks like you're using a implicitly managed connection. It should be
fine to share a single config instance across all threads. The advantage of
HTablePool over this approach is that the number of HTables would be managed
independently from the number of Threads. This may or not be a concern for you,
based on your memory requirements, &c. In your case, you're not specifying an
ExecutorService per HTable, so the HTable instances will be relatively light
weight. Each table will manage it's own write buffer, which can be shared by
multiple threads when autoFlush is disabled and HTablePool is used. This may or
may not be desirable, depending on your use-case.
For what it's worth, HTablePool is marked deprecated in 1.0, will likely be
removed in 2.0. To "future proof" this code, I would move to a single shared
HConnection for the whole application, and a thread-local HTable created
from/with that connection.
-n
On Wed, Feb 25, 2015 at 10:53 AM, Marcelo Valle (BLOOMBERG/ LONDON)
<[email protected]> wrote:
Hi Nick,
I am using HBase version 0.96, I sent the link from version 0.94 because I
haven't found the java API docs for 0.96, sorry about that.
I have created the HTable directly from the config object, as follows:
this.tlConfig = new ThreadLocal<Configuration>() {
@Override
protected Configuration initialValue() {
return HBaseConfiguration.create();
}
};
this.tlTable = new ThreadLocal<HTable>() {
@Override
protected HTable initialValue() {
try {
return new HTable(tlConfig.get(), "HBaseSerialWritesPOC");
} catch (IOException e) {
throw new RuntimeException(e);
}
}
};
I am now sure if the Configuration object should be 1 per thread as well, maybe
I could share this one?
So, just to clarify, would I get any advantage using HTablePool object instead
of ThreadLocal<HTable> as I did?
-Marcelo
From: [email protected]
Subject: Re: HBase connection pool
Hi Marcelo,
First thing, to be clear, you're working with a 0.94 release? The reason I ask
is we've been doing some work in this area to improve things, so semantics may
be slightly different between 0.94, 0.98, and 1.0.
How are you managing the HConnection object (or are you)? How are you creating
your HTable instances? These will determine how the connection is obtained and
used in relation to HTables.
In general, multiple HTable instances connected to tables in the same cluster
should be sharing the same HConnection instance. This is handled explicitly
when you manage your own HConnection and HTables (i.e., HConnection conn = ...
; HTable t = new HTable(TABLE_NAME, conn); ) It's handled implicitly when you
construct via Configuration objects (HTable t = new HTable(conf, TABLE_NAME); )
This implicit option is going away in future versions.
HTable is not safe for concurrent access because of how the write path is
implemented (at least; there may be other portions that I'm not as familiar
with). You should be perfectly fine to have an HTable per thread in a
ThreadLocal.
-n
On Wed, Feb 25, 2015 at 9:41 AM, Marcelo Valle (BLOOMBERG/ LONDON)
<[email protected]> wrote:
In HBase API, does 1 HTable object means 1 connection to each region server
(just for 1 table)?
The docs say
(http://hbase.apache.org/0.94/apidocs/org/apache/hadoop/hbase/client/HTable.html):
"This class is not thread safe for reads nor write."
I got confused, as I saw there is a HTablePool class, but it's only for a table
as well, can't connections be reused for more than 1 table?
In my java application, I used ThreadLocal variables (ThreadLocal<HTable>) to
create an HTable variable per thread. If I do several operations on each
thread, I should still use the same connection, right?
[]s
