-Re: ExecSource->MemoryChannel->AvroSink->AvroSource->FileChannel->HDFSSink throughput question
Juhani Connolly 2013-02-05, 02:22
On 02/02/2013 01:40 AM, Chris Neal wrote:
> Thanks for the help Juhani :) I'll take a look with Ganglia and see
> what things look like.
> Any thoughts on keeping the ExecSource.batchSize,
> MemoryChannel.transactionCapacity, AvroSink.batch-size, and
> HDFSSink.batchSize the same?
It's not really important, so long as the avro batch size is less than
or equal to the channel transaction capacity. The HDFS sinks batch size
is independent of them both.
> I looked at the MemoryChannel code, and noticed that there is a
> timeout parameter passed to doCommit(), where the execption is being
> thrown. Just for fun, I increased it from the default to 10 seconds,
> and now things are running smoothly with the same config as before.
> It's been running for about 24 hours now. A step in the right
> direction anyway! :)
If that fixed it, it sounds like your data is just very bursty and
sometimes gets fed in faster than it's drained out. The solution to that
would be either to enlarge your temporary buffer(the mem channel), to
throttle the incoming data(probably not possible) or to increase drain
speed(more sinks running in parallel)
> Thanks again.
> On Thu, Jan 31, 2013 at 8:12 PM, Juhani Connolly
> <[EMAIL PROTECTED]
> <mailto:[EMAIL PROTECTED]>> wrote:
> Hi Chris,
> The most likely cause of that error is that the sinks are draining
> requests slower than your sources are feeding fresh data. Over
> time it will fill up the capacity of your memory channel, which
> will then start refusing additional put requests.
> You can confirm this by connecting with jmx or ganglia.
> If the write is extremely bursty, it's possible that it's just
> temporarily going over the sink consumption rate, and increasing
> the channel capacity could work. Otherwise, increasing the avro
> batch size, or adding additional avro sinks(more threads) may also
> help. I think that setting up ganglia monitoring and looking at
> the incoming and outgoing event counts and channel fill states
> helps a lot in diagnosing these bottlenecks, you should look into
> doing that.
> On 02/01/2013 02:01 AM, Chris Neal wrote:
>> Hi all.
>> I need some thoughts on sizing/tuning of the above (common) route
>> in FlumeNG to maximize throughput. Here is my setup:
>> *Source JVM (ExecSource/MemoryChannel/AvroSink):*
>> Number of ExecSources in config: 124 (yes, it's a ton. Can't do
>> anything about it :) The write rate to the source files is
>> fairly fast and bursty.
>> ExecSource.batchSize = 1000
>> (so, when all 124 tail -F instances get 1000 events, they all
>> dump to the memory channel)
>> MemoryChannel.capacity = 1000000
>> MemoryChannel.transactionCapacity = 1000
>> (somewhat unclear on what this is. Docs say "The number of
>> events stored in the channel per transaction", but what is a
>> "transaction" to a MemoryChannel?)
>> AvroSink.batchSize = 1000
>> *Destination JVM (AvroSource/FileChannel/HDFSSink)*
>> (Cluster of two JVMs on two servers, each configured the same as
>> per below)
>> -XX:MaxDirectMemorySize is not defined, so whatever the default is
>> AvroSource.threads = 64
>> FileChannel.transactionCapacity = 1000
>> FileChannel.capacity = 32000000
>> HDFSSink.batchSize = 1000
>> HDFSSink.threadPoolSize = 64
>> With this configuration, in about 5 minutes, I get the common
>> "Space for commit to queue couldn't be acquired Sinks are likely
>> not keeping up with sources, or the buffer size is too tight"
>> on the Source JVM. It is no where near the 4g max, rather only
>> at about 2.5g.
>> I'm wondering about the logic of having all the batch
>> sizes/transaction sizes 1000. My thought was that would keep