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It supports only MapReduce (MR) processing model.
It has limited scaling of nodes. Limited to 4000 nodes per cluster.
It has single Namenode to manage the entire namespace.
It has Single-Point-of-Failure (SPOF)
Works on concepts of slots – slots can run either a Map task or a Reduce task
MR has to do both processing and cluster resource management.
Hadoop 2.x
It supports MR as well as other distributed computing models like Spark, Hama, etc
It has better scalability. Scalable up to 10000 nodes per cluster.
Works on concepts of containers. Using containers can run generic tasks.
It has Multiple Namenode servers manage multiple namespace.
YARN does cluster resource management and processing is done using different processing models.
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This question was recently asked at 'Jagan Institute of Management Studies (JIMS)'.This question is still unanswered. Can you please provide an answer.
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Ans. There is no guarantee that the mock will get called as callMethod may never get called. Verify is to make sure that the method gets called. Mock is it return 1 if the method gets called so they both are kind of independent things.
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Ans. It depends on the data type, we use as the parameter.
If it is a simple data type and we validate the input, we may use specific arguments.
Else, we can go for the generic any
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Ans. Java provides its own implementations of the thread pool pattern, through objects called executors. These can be used through executor interfaces or directly through thread pool implementations which does allow for finer-grained control. The java.util.concurrent package contains the following interfaces:
Executor : a simple interface for executing tasks.ExecutorService a more complex interface which contains additional methods for managing the tasks and the executor itself.
ScheduledExecutorService: extends ExecutorService with methods for scheduling the execution of a task.Alongside these interfaces, the package also provides the Executors helper class for obtaining executor instances, as well as implementations for these interfaces.
Generally, a Java thread pool is composed of:
The pool of worker threads, responsible for managing the threads.
A thread factory that is responsible for creating new threads.
A queue of tasks waiting to be executed.
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Ans. Both provide the thread safety but the actual difference come when talk about performance. CHM gives best performance when no of writer threads are less in number.
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Ans. yes, Java is a class-based and object-oriented programming language. It is a platform-independent language i.e. the compiled code can be run on any java supporting platform. It runs on the logic of “Write once, run anywhere”.
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Q687. suppose i have interface and i have declare lots of abstract method in interface But in sub class only two methods are use .than how to use oly two methods.