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Flume >> mail # dev >> Low throughput of FileChannel

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Low throughput of FileChannel
hi all,
    I posted performance of MemoryChannel last week. That's normal
throughput in most environment. Therefore, the performance result of
FileChannel is below expectation with same environments and parameters,
almost 5MB/s.

    I want to know your throughput result of FileChannel specially. Am I
walking with wrong way? It's hard to believe the result.

   Also I have tuning with several code changes, the throughput increasing
to 30MB/s. I think there also have lots of points to impact the performance.

    Any guys, would you give me your throughput result or feedback for

Denny Ye
---------- Forwarded message ----------
From: Denny Ye <[EMAIL PROTECTED]>
Date: 2012/7/25
Subject: Latest Flume test report and problem
hi all,

   I tested Flume in last week with ScribeSource(
https://issues.apache.org/jira/browse/FLUME-1382) and HDFS Sink. More
detailed conditions and deployment cases listed below. Too many 'Full GC'
impact the throughput and amount of events promoted into old generation. I
have applied some tuning methods, no much effect.

   Could someone give me your feedback or tip to reduce the GC problem?
Wish your attention.
PS: Using Mike's report template at


*Flume Performance Test 2012-07-25*


The Flume agent was run on its own physical machine in a single JVM. A
separate client machine generated load against the Flume box in
List<LogEntry> format. Flume stored data onto a 4-node HDFS cluster
configured on its own separate hardware. No virtual machines were used in
this test.

*Hardware specs*

CPU: Inter Xeon L5640 2 x quad-core @ 2.27 GHz (12 physical cores)

Memory: 16 GB

OS: CentOS release 5.3 (Final)

*Flume configuration*

JAVA Version: 1.6.0_20 (Java HotSpot 64-Bit Server VM)

JAVA OPTS: -Xms1024m -Xmx4096m -XX:PermSize=256m -XX:NewRatio=1
-XX:SurvivorRatio=5 -XX:InitialTenuringThreshold=15
-XX:MaxTenuringThreshold=31 -XX:PretenureSizeThreshold=4096

Num. agents: 1

Num. parallel flows: 5

Source: ScribeSource

Channel: MemoryChannel

Sink: HDFSEventSink

Selector: RandomSelector


# list sources, channels, sinks for the agent

agent.sources = seqGenSrc

agent.channels = mc1 mc2 mc3 mc4 mc5

agent.sinks = hdfsSin1 hdfsSin2 hdfsSin3 hdfsSin4 hdfsSin5

# define sources

agent.sources.seqGenSrc.type = org.apache.flume.source.scribe.ScribeSource

agent.sources.seqGenSrc.selector.type = io.flume.RandomSelector

# define sinks

agent.sinks.hdfsSin1.type = hdfs

agent.sinks.hdfsSin1.hdfs.path = /flume_test/data1/

agent.sinks.hdfsSin1.hdfs.rollInterval = 300

agent.sinks.hdfsSin1.hdfs.rollSize = 0

agent.sinks.hdfsSin1.hdfs.rollCount = 1000000

agent.sinks.hdfsSin1.hdfs.batchSize = 10000

agent.sinks.hdfsSin1.hdfs.fileType = DataStream

agent.sinks.hdfsSin1.hdfs.txnEventMax = 1000

# ... define sink #2 #3 #4 #5 ...

# define channels

agent.channels.mc1.type = memory

agent.channels.mc1.capacity = 1000000

agent.channels.mc1.transactionCapacity = 1000

# ... define channel #2 #3 #4 #5 ...

# specify the channel each sink and source should use

agent.sources.seqGenSrc.channels = mc1 mc2 mc3 mc4 mc5

agent.sinks.hdfsSin1.channel = mc1

# ... specify sink #2 #3 #4 #5 ...

*Hadoop configuration*

The HDFS sink was connected to a 4-node Hadoop cluster running CDH3u1. For
different HDFS sink, HDFS wrote data into different path.

*Visualization of test setup*


There are 10 Scribe Clients and each client send 20 million LogEntry
objects to ScribleSource.

*Data description*

List<LogEntry> entries containing a string category and a ByteArray body.
The ByteArray body size is 500 bytes.



Average:       Source: 46.4 MB/s, Sink: 45.2 MB/s

Maximum:    Source: 67.1 MB/s, Sink: 88.3 MB/s

CPU:       Average: 196%, Maximum: 440%


No data loss.

*Heap and GC*

By analyzing JVM Heap, we found that there are many LogEntry objects in
OldGen. We have tried to carry out some optimizations, but the results are
not satisfactory. We will continue to track this limitation.

FullGC Log examples:

[Full GC [PSYoungGen: 1497984K->0K(1797568K)] [PSOldGen:
1720643K->1693741K(2097152K)] 3218627K->1693741K(3894720K) [PSPermGen:
14566K->14566K(262144K)], 5.0027700 secs] [Times: user=5.01 sys=0.00,
real=5.00 secs]

[Full GC [PSYoungGen: 1497960K->0K(1797568K)] [PSOldGen:
1693805K->1752540K(2097152K)] 3191765K->1752540K(3894720K) [PSPermGen:
14571K->14571K(262144K)], 5.0732570 secs] [Times: user=5.07 sys=0.00,
real=5.07 secs]

[Full GC [PSYoungGen: 1497984K->0K(1797568K)] [PSOldGen:
1752540K->1642553K(2097152K)] 3250524K->1642553K(3894720K) [PSPermGen:
14572K->14568K(262144K)], 5.0710730 secs] [Times: user=5.07 sys=0.01,
real=5.08 secs]


Denny Ye
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB