Details
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Bug
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Status: Open
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Major
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Resolution: Unresolved
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1.6.0
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None
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None
Description
We are in the process of migrating from the old Flume to version 1.6. We are using the ThriftSource with the new KafkaSink. Here's what our config looks like:
agent1.channels = ch1 agent1.sources = thriftSrc agent1.sinks = kafka agent1.channels.ch1.type = memory agent1.channels.ch1.capacity = 10000 agent1.channels.ch1.transactionCapacity = 500 # THRIFT agent1.sources.thriftSrc.type = thrift agent1.sources.thriftSrc.channels = ch1 agent1.sources.thriftSrc.bind = 0.0.0.0 agent1.sources.thriftSrc.port = 4042 agent1.sources.thriftSrc.threads = 150 # if we don't set this option, the source keeps creating more and more threads until all heap memory is used up and then it crashes # KAFKA agent1.sinks.kafka.channel = ch1 agent1.sinks.kafka.type = org.apache.flume.sink.kafka.KafkaSink agent1.sinks.kafka.batchSize = 50 agent1.sinks.kafka.brokerList = broker.example.com:9092 agent1.sinks.kafka.requiredAcks = 1 agent1.sinks.kafka.topic = topic1
We have been noticing some bad behavior by the Thrift source/Thrift server using the JMX connection. If we don't restrict the number of threads, it spawns thousands of new threads, apparently one for every message it receives. These threads all have the name "Flume Thrift IPC Thread [number]" and according to the jvisualvm console they are always idle. At some point all of the JVM memory is used up through creating new threads and flume crashes with the following exception:
12 Aug 2015 16:56:11,721 ERROR [Thread-1] (org.apache.thrift.server.TThreadedSelectorServer$SelectorThread.run:544) - run() exiting due to uncaught error java.lang.OutOfMemoryError: unable to create new native thread at java.lang.Thread.start0(Native Method) at java.lang.Thread.start(Thread.java:714) at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:949) at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1360) at org.apache.thrift.server.TThreadedSelectorServer.requestInvoke(TThreadedSelectorServer.java:310) at org.apache.thrift.server.AbstractNonblockingServer$AbstractSelectThread.handleRead(AbstractNonblockingServer.java:209) at org.apache.thrift.server.TThreadedSelectorServer$SelectorThread.select(TThreadedSelectorServer.java:576) at org.apache.thrift.server.TThreadedSelectorServer$SelectorThread.run(TThreadedSelectorServer.java:536)
When we set the option to restrict the number of threads, the server sticks to that number and runs smoothly, however it drops messages occasionally (may have a different cause).
I am wondering whether this is a bug or in some way expected behavior? What are the best practices for using a ThriftSource? Are there further parameters to possibly tune (like channel.capacity)?