3 Replies Latest reply on Sep 30, 2015 7:29 AM by adinn

Instrumenting Spark Streaming with Byteman

shamte Sep 25, 2015 1:49 PM

Hi,

I am trying to modify spark streaming program using byteman (see the Java and Byteman rule snippets below) .

JavaPairInputDStream<String, String> messages = KafkaUtils.createDirectStream(
          jssc,
          String.class,
          String.class,
          StringDecoder.class,
          StringDecoder.class,
          kafkaParams,
          topicsSet
      );


JavaDStream<String> lines = messages.map(tuple2 -> tuple2._2());
JavaDStream<String> words = lines.flatMap(str -> Arrays.asList(str.split(" ")));

RULE accessing the parameters of "createDirectStream" method
CLASS org.apache.spark.streaming.kafka.KafkaUtils
METHOD createDirectStream
AT ENTRY
IF true
DO
  traceln("**** topic = " + $7);
ENDRULE


RULE accessing the parameters of "flatMap" method
CLASS org.apache.spark.streaming.api.java.JavaDStream
METHOD flatMap
AT ENTRY
BIND value = $1
IF (value.contains("trace")
DO
  $1 = $1 + "|" + System.currentTimeMillis();
  traceln("new value = " + $1);
ENDRULE

The first rule which is applied to KafkaUtils.createDirectStream method (line 1) works fine. But the second rule which is applied to JavaDStream.flatMap method (line 13)

doesn't seem to work at all, and byteman does not through any error or exception. Any insight please. One thing I know is that Spark is written with Scala,

but Scala source code is compiled to Java bytecode and the resulting executable code runs on a JVM. And this shouldn't be the problem as the first rule works fine. Any help please.

regards

1. Re: Instrumenting Spark Streaming with Byteman

adinn Sep 28, 2015 2:47 AM (in response to shamte)

Hi Saleh,

Can you confirrm that this is the correct text for your rule? if it is then I believe you have a typo in trhe pocndtion (missing bracket at end). Try fixing that and then let me know what happens.

If this is the case ten run your JVM with -Dorg.jboss.byteman.verbose on the java command line. You ought to see a parse error message.
Better is to check your rules offline efore runnign th eprogram. If you have downloaded a Byteman zip release then you can use the bmcheck script in th ebin directory to check your rules as follows

bmcheck.sh -cp /path/to/appcode.jar -cp /path/to/otherappcode.jar myscript.btm

(On windows youcan use bmcheck.bat)

If you are using maven to run your tests then you can use the Byteman maven rulecheck plugin to check you rules. See the Byteman docs page for the tutorial on how to use this plugin.

http://www.jboss.org/byteman/documentation

regards,

Andrew Dinn
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2. Re: Instrumenting Spark Streaming with Byteman

shamte Sep 30, 2015 4:35 AM (in response to adinn)
Hi Andrew,
Thank you for the response. As for the missing bracket, it was not the main problem. But I finally figured out how to do it. The method "flatMap" accepts a function as parameter and in my case I passed lambda expression "str -> Arrays.asList(str.split(" "))". With this, byteman returns a reference to that expression. But after changing the rule to as shown below, I was able to access the string object "str".

##Add timestamp to the trace packets inside the Arrays.asList method RULE inside "JavaDStream.flatMap" method CLASS Arrays METHOD asList AT ENTRY BIND value = $1 IF (value.get(0).toString().contains("trace")) DO str = value.get(0); str = str + "||at flatMap:" + System.currentTimeMillis(); $1.set(0, str); traceln("byteman at flatMap: " + str) ENDRULE
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3. Re: Instrumenting Spark Streaming with Byteman

adinn Sep 30, 2015 7:29 AM (in response to shamte)

Hi Saleh,

Thanks for following this up andI am glad you sorted out the problem. I would still recommend using bmcheck or the maven rulecheck plugin if you can. Both of those should at lest have told you that the rule could not be injected into the target class.

regards,

Andrew Dinn
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