HBase: MSLAB and CMS vs. ParallelGC

By Anonymous -
Tuning Java opts for HBase, for example, are necessary steps to get the best performance and stability in large installations. The optimal recommendation looks like:
HBASE_OPTS="-XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -XX:+CMSParallelRemarkEnabled"

But you can also achieve great success with:
HBASE_OPTS="-server -XX:+UseParallelGC XX:+UseParallelOldGC -XX:ParallelGCThreads=8"

What are the differences between ParallelGC and CMS? 

CMS uses more CPU, but runs concurrently. If a thread is failing, CMS falls back to a non-parallel mode and stops the VM for the entire time it's collecting. But this risk can be minimized by using MSLAB in your HBase configuration.
ParallelGC have a better throughput and longer pause times, and stop the VM on every collection. Means for HBase, you'll have a pause (around 1 sec per GB), which can lead on high loaded clusters to outages in a non acceptable time range.

MSLAB (MemStore-Local Allocation Buffers)

The most GC pauses are caused by old-gen fragmentation, and CMS can't defragment without pause the VM (Juliet pause). MSLAB now moves the memstore allocations into the configured chunks into the old generation. When you start or upgrade into HBase 0.92x, MSLAB is enabled per default (http://hbase.apache.org/book/upgrade0.92.html). 

hbase.hregion.memstore.mslab.enabled=true
hbase.hregion.memstore.mslab.chunksize=2MB (2MB per default)
hbase.hregion.memstore.mslab.max.allocation=256KB (256KB per default)

More about MSLAB you can find in Todd's presentation: http://www.slideshare.net/cloudera/hbase-hug-presentation


Comments

  1. Ciana Langham11 December, 2019

    Hello! Thank you for sharing with us this awesome post. I decided to add that if you happen to look for a writing help then it's better to apply to the writing service where you can buy research papers

    ReplyDelete
  2. Samanta Woods18 December, 2019

    Quite good site where you can find a lot of interesting information and thanks to your site I found one another which now always helps me with writing resumes, so if you have the same problem as me and want to order resume summary section you can easily cope with that task just ask for help of writers proffessional writers at prime-resume.com where they are always ready to handle with different kind of resumes and CVs

    ReplyDelete

Post a Comment

Popular posts from this blog

Deal with corrupted messages in Apache Kafka

By -
Under some strange circumstances it can happen that a message in a Kafka topic is corrupted. This happens often by using 3rd party frameworks together with Kafka. Additionally, Kafka < 0.9 has no lock at Log.read() at the consumer read level, but has a lock on Log.write(). This can cause a rare race condition, as described in KAKFA-2477 [1]. Probably a log entry looks like: ERROR Error processing message, stopping consumer: (kafka.tools.ConsoleConsumer$) kafka.message.InvalidMessageException: Message is corrupt (stored crc = xxxxxxxxxx, computed crc = yyyyyyyyyy Kafka-Tools Kafka stores the offset of every consumer in Zookeeper. To read out the offsets, Kafka provides handy tools [2]. But also zkCli.sh can be used, at least to display the consumer and the stored offsets. First we need to find the consumer for a topic (> Kafka 0.9): bin/kafka-consumer-groups.sh --zookeeper management01:2181 --describe --group test Prior to Kafka 0.9 the only possibility to get this i
Read more

Hive query shows ERROR "too many counters"

By Anonymous -
A hive job face the odd " Too many counters:"  like Ended Job = job_xxxxxx with exception 'org.apache.hadoop.mapreduce.counters.LimitExceededException(Too many counters: 201 max=200)' FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.MapRedTask Intercepting System.exit(1) These happens when operators are used in queries ( Hive Operators ). Hive creates 4 counters per operator, max upto 1000, plus a few additional counters like file read/write, partitions and tables. Hence the number of counter required is going to be dependent upon the query.  To avoid such exception, configure " mapreduce.job.counters.max " in mapreduce-site.xml to a value above 1000. Hive will fail when he is hitting the 1k counts, but other MR jobs not. A number around 1120 should be a good choice. Using " EXPLAIN EXTENDED " and " grep -ri operators | wc -l " print out the used numbers of operators. Use this value to tweak the MR s
Read more

Life hacks for your startup with OpenAI and Bard prompts

By -
OpenAI and Bard   are the most used GenAI tools today; the first one has a massive Microsoft investment, and the other one is an experiment from Google. But did you know that you can also use them to optimize and hack your startup? Even creating pitch scripts, sales emails, and elevator pitches with one (or both) of them helps you not only save time but also validate your marketing and wording. Curios? Here a few prompt hacks for startups to create / improve / validate buyer personas, your startups mission / vision statements, and USP definitions. Introduce yourself and your startup Introduce yourself, your startup, your website, your idea, your position, and in a few words what you are doing to the chatbot: Prompt : I'm NAME and our startup NAME, with website URL, is doing WHATEVER. With PRODUCT NAME, we aim to change or disrupt INDUSTRY. Bard is able to pull information from your website. I'm not sure if ChatGPT can do that, though. But nevertheless, now you have laid a grea
Read more