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Questions tagged [off-heap]

28 questions
185
votes
6 answers

Difference between "on-heap" and "off-heap"

Ehcache talks about on-heap and off-heap memory. What is the difference? What JVM args are used to configure them?
Synesso
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18
votes
2 answers

spark off heap memory config and tungsten

I thought that with the integration of project Tungesten, spark would automatically use off heap memory. What for are spark.memory.offheap.size and spark.memory.offheap.enabled? Do I manually need to specify the amount of off heap memory for…
Georg Heiler
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12
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2 answers

Happens-before for direct ByteBuffer

I have a direct ByteBuffer (off-heap) in one thread and safely publish it to a different thread using one of the mechanisms given to me by JMM. Does the happens-before relationship extend to the native (off-heap) memory wrapped by the ByteBuffer? If…
Philippe Marschall
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5
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2 answers

How to serialise/deserialise long[] value with get/set on random indices using Chronicle Map?

I am new to chronicle-map. I am trying to model an off heap map using chronicle-map where the key is a primitive short and the value is a primitive long array. The max size of the long array value is known for a given map. However I will have…
junkie
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4
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0 answers

How to know jvm memory usages: "heap memory" and "off-heap memory"

I want to see the details about "heap memory" and "off-heap memory". I have used jmap to see the heap memory usages, and I want to know the "off-heap memory" usages. I tried to use pamap pid command, but only can see the total memory used by the…
fcbflying
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3
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0 answers

JDK 11 (and newer) DirectByteBuffer Hold Large Off-Heap Memory Even At Startup

Our application uses alot of DirectByteBuffer's object via nio's FileChannel.map() and ByteBuffer.allocateDirect() to load and process files (ex. DICOM). The code is written in java 8 but compiled in java 11.0.3. We profiled our application using…
user1652398
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3
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0 answers

mapDb store list object in off heap or file

I want to use mapDb to store List object syntax wise not throwing any error, but after getting data for map getting class cast exception. but I do see below warnings in eclipse: Multiple markers at this line Type safety: The expression of type…
Ramesh Mandri
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2
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1 answer

How does Chronicle map behave when off heap memory is full?

I download some files, and store them off heap using an in-memory chronicle map. I wanted to understand the behaviour of chronicle map, when I exceed the amount of native (off-heap) memory available. I have 2 Questions regarding it: Does the data…
Sarthak Agarwal
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2
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0 answers

Why and how to find where JVM off-heap memory leaks occur

I have a Java project which shows a memory leak in the product environment. We can see its memory expand and grow bigger and bigger using 'top' or 'cat /proc/PID/status|grep VmRSS', but its JVM heap remains in a good state, which means the heap…
sheen
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2
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1 answer

Difference between On-heap and Off-heap memory

Can someone explain the difference between on-heap memory and off-heap memory?Does the off-heap memory show on the JVM memory size?Are the off-heap all pointers?
Shellong
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2
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1 answer

Are off-heap memory and Stack memory the same?

I know the difference between Stack and Heap memory however in many blogs I came across this word off-heap memory. I went through many blogs and youtube videos to find out if there is any relation between off-heap memory and Stack memory? According…
Alex Raj Kaliamoorthy
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2
votes
2 answers

Source of Java9Memory in Chronicle

I got curious on the off-heap mechanism used by the openHFT project and am looking for the class file below (couldn't find anywhere in github) as defined by the source code here: Class java9MemoryClass = Class …
toddlermenot
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1
vote
1 answer

Apache Ignite Resource Configuration (CPUs, Memory Size, ...)

I'm using Apache Ignite to configure an In-Memory Data Grid (IMDG) cluster in localhost. For each ignite node(process) that makes up the IMDG cluster, I would like to configure 1) the capacity of off-heap memory, 2) the number of cores. Off-Heap…
Yunkeuk Kim
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1
vote
1 answer

Apache Ignite consumes more memory than expected

I deploy my ignite cluster on google kubenetes engine (gke), which consists of two ignite server nodes. I have a table with 6,000,000 records, and each around 220 bytes, in total 1.33GB. I set one backups for this table and set 5 indexes. As the…
Vincent Y
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1
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1 answer

Is ChronicleMap an improved Concurrent HashMap?

I am new to off-heap storage in JVM, and ChronicleMap looks good for off heap things. But my main concern is related to performance mostly. I did run simple test with config ChronicleMapBuilder builder = …
Vivek Dhiman
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