Large-Scale Data Engineering and Analytics in Cloud

Performance Tuning and Optimization / Internals, Research

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  • Data Skew,  Distributed,  Pig,  Tez

    Reduce Number of Output Files for Skewed Data – ORDER in Apache Pig – Sampler and Weighted Range Partitioner to Balance Reducers

    January 25, 2019

    One of our event tables is very large, it contains billions of rows per day. Since the analytics team is often interested in specific events only it makes sense to process the raw events and generate a partition for every event type. Then when a data analyst runs an ad-hoc query, it reads data for the required event type only increasing the query performance.

    The problem is that there are 3,000 map tasks are launched to read the daily data and there are 250 distinct event types, so the mappers will produce 3,000 * 250 = 750,000 files per day. That’s too much.

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    dmtolpeko
  • Hive,  Memory,  Tez,  YARN

    Tez Memory Tuning – Container is Running Beyond Physical Memory Limits – Solving By Reducing Memory Settings

    January 21, 2019

    Can reducing the Tez memory settings help solving memory limit problems? Sometimes this paradox works.

    One day one of our Hive query failed with the following error: Container is running beyond physical memory limits. Current usage: 4.1 GB of 4 GB physical memory used; 6.0 GB of 20 GB virtual memory used. Killing container.

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    dmtolpeko
  • Amazon,  AWS,  EMR,  YARN

    YARN Resource Manager Silent Restarts – Java Heap Space Error – Amazon EMR

    January 4, 2019

    When you run a job in Hadoop you can notice the following error: Application with id 'application_1545962730597_2614' doesn't exist in RM. And later looking at the YARN Resource Manager UI at http://<RM_IP_Address>:8088/cluster/apps you can see low Application ID numbers:

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    dmtolpeko

Recent Posts

  • Jan 15, 2021 Parquet 1.x File Format – Footer Content
  • Jan 02, 2021 Flink and S3 Entropy Injection for Checkpoints
  • Jun 25, 2020 Hadoop YARN – Monitoring Resource Consumption by Running Applications in Multi-Cluster Environments
  • Jun 18, 2020 How Map Column is Written to Parquet – Converting JSON to Map to Increase Read Performance
  • Jun 09, 2020 Flink Streaming to Parquet Files in S3 – Massive Write IOPS on Checkpoint

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